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114

Keysight

 

U1251B/U1252B User’s and Service Guide

5 Maintenance

 

 

Replacing the fuse

Follow the procedures below to replace the fuse.

1

Turn the meter off and disconnect the test leads from the 
external equipment. Make sure to remove the adaptor.

2

Wear clean/dry gloves and do not touch any other 
component except the fuse and plastic parts. The current 
calibration is considered shunt only, so do not recalibrate 
the meter after replacing the fuse.

3

Remove the battery cover compartment to replace the 
fuse.

4

Loosen the three screws on the bottom case and remove 
the cover.

5

Loosen the two screws on the top corners to lift the 
circuit board.

6

Gently remove the defective fuse by prying one end of the 
fuse loose and removing it out of the fuse bracket.

7

Replace with a new fuse of the same size and rating. 
Make sure the new fuse is centered in the fuse holder.

8

Ensure that the rotary switch on the top case and the 
circuit board switch stay on the OFF position.

9

Then re- fasten the circuit board and the bottom cover.

10

Refer to the table below for the part number, rate, and 
size of the fuses.

N O T E

This manual provides only the fuse replacement procedures, but not the 
fuse replacement markings. 

Summary of Contents for U1251B

Page 1: ...Keysight U1251B and U1252B Handheld Digital Multimeter User s and Service Guide ...

Page 2: ......

Page 3: ...Keysight U1251B U1252B User s and Service Guide I ...

Page 4: ...he max imum extent permitted by applicable law Keysight disclaims all warran ties either express or implied with regard to this manual and any infor mation contained herein including but not limited to the implied warran ties of merchantability and fitness for a particular purpose Keysight shall not be liable for errors or for inciden tal or consequential damages in con nection with the furnishing...

Page 5: ...isk of electric shock Three phase alternating current Caution risk of danger refer to this manual for specific Warning or Caution information Earth ground terminal Caution hot surface Protective conductor terminal Out position of a bi stable push control Frame or chassis terminal In position of a bi stable push control Equipotentiality Category III 1000 V overvoltage protection Equipment protected...

Page 6: ... or with specific warnings elsewhere in this manual violates safety standards of design manufacture and intended use of the instrument Keysight Technologies assumes no liability for the customer s failure to comply with these requirements CAUTION Turn off the circuit power and discharge all high voltage capacitors in the circuit before you perform resistance continuity diodes or capacitance tests ...

Page 7: ...the connectors Do not use the meter if it is damaged Inspect the test probes for damaged insulation or exposed metal and check for continuity Do not use the test probe if it is damaged Do not use any other AC charger adaptor apart from the one certified by Keysight with this product Do not use repaired fuses or short circuited fuse holders For continued protection against fire replace the line fus...

Page 8: ... compliance with the Australia EMC Framework regulations under the terms of the Radio Communication Act of 1992 ICES NMB 001 indicates that this ISM device complies with the Canadian ICES 001 Cet appareil ISM est confomre a la norme NMB 001 du Canada This instrument complies with the WEEE Directive 2002 96 EC marking requirement This affixed product label indicates that you must not discard this e...

Page 9: ...irective Annex 1 this instrument is classified as a Monitoring and Control Instrument product The affixed product label is as shown below Do not dispose in domestic household waste To return this unwanted instrument contact your nearest Keysight Technologies or visit www keysight com environment product for more information Keysight Technologies through Rechargeable Battery Recycling Corporation R...

Page 10: ...the functions and features that are available for the U1251B and U1252B digital multimeter 4 Changing The Default Setting This chapter shows you how to change the default factory settings of the U1251B and U1252B and other available setting options 5 Maintenance This chapter will go through how to troubleshoot the handheld digital multimeter if any problems arise 6 Performance Tests and Calibratio...

Page 11: ...The Declaration of Conformity DoC for this instrument is available on the Web site You can search the DoC by its product model or description http www keysight com go conformity NOTE If you are unable to search for the respective DoC please contact your local Keysight representative ...

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Page 13: ...lecting display with the Hz button 15 Selecting display with the Dual button 17 Selecting display with the Shift button 20 The terminals at a glance 22 2 Making Measurements Understanding The Measurement Instructions 24 Measuring Voltage 24 Measuring AC voltage 25 Measuring DC voltage 26 Measuring AC and DC Signals U1252B only 27 Measuring Current 28 µA mA measurement 28 Percentage scale of 4 mA t...

Page 14: ...2 Data Hold Trigger Hold 54 Refresh Hold 55 Null Relative 57 Decibel Display 59 1 ms Peak Hold 61 Data Logging 63 Manual logging 63 Interval logging 65 Reviewing logged data 67 Square Wave Output for U1252B 69 Remote Communication 73 4 Changing The Default Setting Selecting Setup Mode 76 Setting Data Hold Refresh Hold Mode 80 Setting Data Logging Mode 81 Setting Thermocouple Types U1252B only 82 S...

Page 15: ...ng Baud Rate 92 Setting Parity Check 93 Setting Data Bit 94 Setting Echo Mode 95 Setting Print Mode 96 Returning to Default Factory Settings 97 Setting the Battery Voltage 98 Setting the Filter 99 5 Maintenance Introduction 102 General maintenance 102 Battery replacement 102 Storage considerations 104 Charging the battery 105 Fuse checking procedure 112 Replacing the fuse 114 Troubleshooting 116 R...

Page 16: ...splay 123 Current terminal test 124 Charge terminal alert test 125 Test Considerations 126 Calibration Security 127 Performance Verification Tests 128 Unsecuring the instrument for calibration 136 Calibration Process 139 Using the front panel for adjustments 140 Adjustments Consideration 141 Valid adjustment input values 142 Adjustment Procedure 143 Finishing the Adjustment 150 To Read the Calibra...

Page 17: ...1252B 163 Capacitance Specifications 164 Temperature Specifications 164 Frequency Specifications 165 Duty Cycle and Pulse Width Specifications 165 Frequency Sensitivity Specifications 166 Peak Hold Specifications 168 Frequency Counter Specifications for U1252B 168 Square Wave Output for U1252B 169 Operating Specifications 171 Display update rate approximate 171 Input impedance 172 ...

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Page 19: ... 2 8 Audible continuity conductance and resistance test 36 Figure 2 9 Conductance measurement 38 Figure 2 10 Measuring forward bias of diode 40 Figure 2 11 Measuring reverse bias of diode 41 Figure 2 12 Capacitance measurements 43 Figure 2 13 Connecting the thermal probe into the non compensa tion transfer adapater 45 Figure 2 14 Connecting the probe with adapter into the multimeter 45 Figure 2 15...

Page 20: ... Figure 4 7 Auto power saving setup 88 Figure 4 8 scale readout setup 89 Figure 4 9 Beep frequency setup 90 Figure 4 10 Backlit timer setup 91 Figure 4 11 Baud rate setup remote control 92 Figure 4 12 Parity check setup 93 Figure 4 13 Data bit setup for remote control 94 Figure 4 14 Echo mode setup for remote control 95 Figure 4 15 Print mode setup for remote control 96 Figure 4 16 Reset setup 97 ...

Page 21: ...able setting options in Setup mode 77 Table 4 2 Filter defaults 100 Table 5 1 Battery voltage and corresponding percentage of charg es in standby and charging modes 106 Table 5 2 Error messages 108 Table 5 3 Measurement readings for fuse checking 113 Table 5 4 Fuse specifications 115 Table 5 5 Basic troubleshooting procedures 116 Table 6 1 Recommended Test Equipment 122 Table 6 2 Verification Test...

Page 22: ...fications 165 Table 7 11 Duty cycle and pulse width specifications 165 Table 7 12 Frequency sensitivity and trigger level specifications for voltage measurements 166 Table 7 13 Frequency sensitivity specifications for current measurements 167 Table 7 14 Peak hold specifications for dc voltage and current measurements 168 Table 7 15 Frequency counter divide by 1 specifications 168 Table 7 16 Freque...

Page 23: ...glance 6 The rear panel at a glance 7 The rotary switch at a glance 8 The keypad at a glance 9 The display at a glance 11 Selecting display with the Hz button 15 Selecting display with the Dual button 17 Selecting display with the Shift button 20 The terminals at a glance 22 This chapter contains information on the Keysight U1251B and U1252B handheld multimeter front panel rotary switch keypad dis...

Page 24: ... GΩ 50 nS Capacitance measurement of up to 100 mF Frequency counter of up to 20 MHz U1252B only The scale readout for 4 20 mA or 0 20 mA measurement dBm with selectable reference impedance 1 ms Peak Hold to catch inrush voltage and current easily Temperature test with selectable 0 C compensation without ambient temperature compensation K type for U1251B and J K types temperature measurement U1252B...

Page 25: ... only Quick Start Guide Certificate of Calibration Contact your nearest Keysight Sales Office if any of the above are missing Inspect the shipping containing for damage Signs of damage may include a dented or torn shipping container or cushioning material that indicates signs of unusual stress or compacting Save the packaging material in case the multimeter needs to be returned Please refer to the...

Page 26: ...ull the tilt stand outwards to its maximum reach Figure 1 1 Tilt stand at 60 To adjust the meter to a 30 standing position bend the tip of the stand so that it is parallel to the ground before pulling the stand outwards to its maximum reach Figure 1 2 Tilt stand at 30 To PC host Tilt stand at 60 IR USB cable To PC host Tilt stand at 30º IR USB cable ...

Page 27: ...tion follow the steps shown in Figure 1 3 below Figure 1 3 Tilt stand at hanging position 3 Flip the tilt stand over until this side of 4 Re attach the tilt stand to an upright position 1 Extend the tilt stand until itsmaximum reach 2 Detach the tilt stand the stand is facing the multimeter as opposed to facing you ...

Page 28: ...6 Keysight U1251B U1252B User s and Service Guide 1 Getting Started Tutorial The front panel at a glance Figure 1 4 U1252B front panel Display Keypad Rotary Switch Terminal Connectors ...

Page 29: ...Getting Started Tutorial 1 Keysight U1251B U1252B User s and Service Guide 7 The rear panel at a glance Figure 1 5 Rear panel IR Communication Port Test probe holders Battery access cover Tilt stand ...

Page 30: ...de U1252B only or OFF 2 AC voltage 3 AC voltage DC voltage or DC AC voltage U1252B only 4 DC mV AC mV AC DC mV U1252B only 5 Resistance Ω Continuity and Conductance nS 6 Frequency counter U1252B only or Diode 7 Capacitance or Temperature 8 DC µA AC µA AC DC µA 9 DC mA DC current AC mA AC current or AC DC current 10 Square wave output Duty cycle or Pulse width output for U1252B and OFF for U1251B 2...

Page 31: ...fter 30s default 1 displays the battery capacity for 3 seconds 2 freezes the measured value In Data Hold mode press again to trigger hold of the next measured value In Refresh Hold mode reading updates automatically once reading is stable and count setting is exceeded 1 enters Dynamic Recording mode Press again to scroll through Max Min Avg and present readings indicated by MAXMINAVG on display 3 ...

Page 32: ...ch to positive or negative pulse enters logging mode In manual data logging press to log data manually into memory In automatic data logging data logs automatically 1 Press for more than 1 second to exit auto data logging mode Notes for keypad descriptions and functions 1 See Table 4 1 on page 77 for details of available options 2 When rotary switch is at press to switch to ºC or ºF display When r...

Page 33: ... rotary switch position This is followed by a wake up feature The meter will then enter power save mode once auto power off APF is enabled To wake the meter up 1 Turn the rotary switch to OFF position then ON again 2 Press any button for rotary switch position that is not at square wave output position U1252B only 3 To set the rotary switch at square wave out position press only the Dual Range and...

Page 34: ...t Charging capacitor as capacitance measurement Negative slope for pulse width ms and duty cycle measurement Discharging capacitor as capacitance measurement Low battery indication Auto power off enable Refresh auto Hold TRIG Trigger manual Hold MAXMINAVG Dynamic Recording mode Present value on primary display MAX Dynamic Recording mode Maximum value on primary display MIN Dynamic Recording mode M...

Page 35: ...imary display dBm Decibel unit relative to 1 mW dBV Decibel unit relative to 1 V MkHz Frequency units Hz kHz MHz MkΩ Resistance units Ω kΩ MΩ nS Conductance unit mV Voltage units mV V µmA Current units µA mA A Duty cycle measurement ms Pulse width unit µmnF Capacitance units nF µF mF ºC Celsius temperature unit ºF Fahrenheit temperature unit Percentage scale readout proportional to DC 0 20 mA Perc...

Page 36: ...ts When frequency duty cycle and pulse width are indicated on the primary display during voltage or current measurement the bar graph represents the voltage or current value When 4 20 mA scale or 0 20 mA scale is indicated on the primary display the bar graph represents the current value and not the percentage value Table 1 5 Secondary display symbols LCD symbol Description AC DC DC AC Polarity di...

Page 37: ...cting display with the Hz button The frequency measurement feature helps to detect the presence of harmonic currents in neutral conductors and determines whether these neutral currents are the result of unbalanced phases or non linear loads Press to access the frequency measurement mode for current or voltage measurements voltage or current on the secondary Table 1 6 Analog bar range and counts Ra...

Page 38: ...r you press and hold for more than 1 second Table 1 7 Selecting display with the Hz button Rotary switch position Function Primary Display Secondary Display for U1252B AC voltage Frequency Hz AC V Pulse width ms Duty cycle for U1251B for U1252B DC voltage Frequency Hz DC V Pulse width ms Duty cycle for U1252B AC DC voltage Frequency Hz AC DC V Pulse width ms Duty cycle AC voltage Frequency Hz AC m...

Page 39: ...DC current for U1252B Frequency Hz AC DC µA Pulse width ms Duty cycle AC current Frequency Hz AC mA or A Pulse width ms Duty cycle DC current Frequency Hz DC mA or A Pulse width ms Duty cycle AC DC current for U1252B Frequency Hz AC DC mA or A Pulse width ms Duty cycle Hz Frequency counter press to select frequency division by 1 for U1252B Frequency Hz 1 Pulse width ms Duty cycle Hz Frequency coun...

Page 40: ...U1252B DC voltage DC V Hz DC coupling dBm or dBV 1 DC V DC V AC V for U1252B DC V Ambient temperature C or F for U1252B AC DC voltage AC DC V Hz AC coupling dBm or dBV 1 AC DC V AC DC V AC V AC DC V DC V AC DC V Ambient temperature C or F AC voltage AC mV Hz AC coupling dBm or dBV 1 AC mV AC mV DC mV AC mV Ambient temperature C or F DC voltage DC mV Hz DC coupling dBm or dBV 1 DC mV DC mV AC mV DC...

Page 41: ...mperature C or F AC DC μA Hz AC coupling AC DC current AC DC μA AC μA AC DC μA DC μA AC DC μA Ambient temperature C or F DC mA Hz DC coupling DC current DC mA AC mA 0 20 or 4 20 DC mA DC mA Ambient temperature C or F AC mA Hz AC coupling AC current AC mA DC mA AC mA Ambient temperature C or F AC DC mA Hz AC coupling AC DC current for U1252B AC DC mA AC mA AC DC mA DC mA AC DC mA Ambient temperatur...

Page 42: ...ent AC DC A AC A for U1252B AC DC A DC A AC DC A Ambient temperature C or F Capacitance Diode Resistance nS Conductance nF V Ω nS Ambient temperature C or F Temperature C F Ambient temperature C or F C F Ambient temperature C or F 0 C compensation select by pressing Table 1 8 Selecting display with the Dual button continued Table 1 9 Selecting display with the Shift button Rotary switch position F...

Page 43: ...ce Temperature AC Current DC μA AC μA AC DC μA for U1252B DC Current DC mA AC mA AC DC mA 0 20 or 4 20 AC DC Current DC A AC A AC DC A for U1252B Square wave output for U1252B Duty cycle Pulse width ms Notes for selecting display with the Shift button 1 Press to switch between dBm and dBV measurement 2 Press for more than 1 second to return to AC V measurement only Table 1 9 Selecting display with...

Page 44: ...ter do not exceed the input limit Table 1 10 Terminal connections for different measuring functions Rotary switch position Input terminals Overload protection COM 1000 V R M S for U1252B for U1251B 1000 V R M S for short circuit 0 3 A Ω μA mA COM 440 mA 1000 V 30 kA fast acting fuse A COM 11 A 1000 V 30 kA fast acting fuse for U1252B COM COM 440 mA 1000 V fast acting fuse ...

Page 45: ...nly 27 µA mA measurement 28 Percentage scale of 4 mA to 20 mA 30 A ampere measurement 32 Frequency Counter 33 Measuring Resistance Conductance and Testing Continuity 35 Testing Diodes 39 Measuring Capacitance 42 Measuring Temperature 44 Alerts and Warning During Measurement 48 Overload alert 48 Input warning 48 Charge terminal alert 49 This chapter contains information on how to make measurements ...

Page 46: ...ves staircase waves and other waveforms without any DC offset For AC with DC offset use AC DC measurement on or rotary switch location Applies only to U1252B Table 2 1 Numerical steps descriptions No Instructions Turn the rotary switch to the measurement option shown in the diagram Connect the test leads into the input terminals shown in the diagram Probe the test points Read the results on the di...

Page 47: ...AC voltage as shown in Figure 2 1 Probe the test points and read the display Figure 2 1 Measuring AC voltage Red Lead Black Lead NOTE Press to display frequency on the secondary display See Table 1 8 of Selecting display with the Dual button on page 17 for a list of the different combinations available on the secondary display ...

Page 48: ...ge signals with a DC offset refer to the Measuring AC and DC Signals U1252B only on page 27 For measuring DC voltage from a mixed signal in DC measurement mode ensure that the Filter is enabled Refer to Setting the Filter on page 99 To avoid possible electric shock or personal injury enable the Low Pass Filter to verify the presence of hazardous DC voltages Displayed DC voltage values can be influ...

Page 49: ... better accuracy when measuring the DC offset of an AC voltage measure the AC voltage first Note the AC voltage range then manually select a DC voltage range equal to or higher than the AC range This procedure improves the accuracy of the DC measurement by ensuring that the input protection circuits are not activated ...

Page 50: ...to ensure is shown on the display For μA measurement set the rotary switch to and connect the positive test lead to μA mA For mA measurement set the rotary switch to and connect the positive test lead to μA mA For A ampere measurement set the rotary switch to and connect the positive test lead to A Press to display dual measurements See Table 1 8 of Selecting display with the Dual button on page 1...

Page 51: ...Making Measurements 2 Keysight U1251B U1252B User s and Service Guide 29 Figure 2 3 Measuring μA and mA current Red Lead Black Lead ...

Page 52: ...ollows NOTE Press to select percentage scale display Ensure that or is shown on the display The percentage scale for 4 mA to 20 mA or 0 mA to 20 mA is calculated using its corresponding DC mA measurement The U1251B and U1252B will automatically optimize the best resolution according to Table 2 2 below Press to change the measurement range Table 2 2 Percentage scale and measurement range Percentage...

Page 53: ...Making Measurements 2 Keysight U1251B U1252B User s and Service Guide 31 Figure 2 4 Measuring scale of 4 20 mA Red Lead Black Lead ...

Page 54: ...A ampere as shown in Figure 2 5 Probe the test points and read the display Figure 2 5 A ampere current measurement NOTE Connect the red and black test leads to the 10 A input terminal A and COM respectively The meter is set to A measurement automatically when the red test lead is plugged into the A terminal Red Lead Black Lead ...

Page 55: ...age measurement instead of frequency counter NOTE Press to select the Frequency counter Hz function 1 on the secondary display means the input signal frequency is divided by 1 This allows signals of up to a maximum frequency of 985 kHz to be measured If the reading is unstable or is zero press to select the division of the input signal frequency by 100 This allows for a higher frequency range of u...

Page 56: ...34 Keysight U1251B U1252B User s and Service Guide 2 Making Measurements Figure 2 6 Measuring frequency Red Lead Black Lead ...

Page 57: ... to measure resistance as shown in Figure 2 7 Then probe the test points by shunting the resistor and read the display Figure 2 7 Measuring resistance CAUTION Disconnect the circuit power and discharge all high voltage capacitors before measuring resistance to prevent any possible damage to the multimeter or the device under test Red Lead Black Lead ...

Page 58: ...nd Service Guide 2 Making Measurements Press to scroll through audible continuity conductance and resistance tests as shown in Figure 2 8 Figure 2 8 Audible continuity conductance and resistance test Audible continuity Press Press Press ...

Page 59: ...as shown in Figure 2 9 Probe the test points and read the display The conductance measurement enables the measurement of very high resistance of up to 100 GΩ As the high resistance readings are susceptible to noise you can capture the average readings by using the Dynamic Recording mode Refer to the section Dynamic Recording on page 52 for more information Table 2 3 Audible continuity measurement ...

Page 60: ...38 Keysight U1251B U1252B User s and Service Guide 2 Making Measurements Figure 2 9 Conductance measurement Red Lead Black Lead ...

Page 61: ...st result is based on the following The diode is considered good if the meter displays OL in reverse bias mode The diode is considered shorted if the meter displays approximately 0 V in both forward and reverse bias modes and the meter beeps continuously The diode is considered open if the meter displays OL in both forward and reverse bias modes CAUTION Disconnect the circuit power and discharge a...

Page 62: ...40 Keysight U1251B U1252B User s and Service Guide 2 Making Measurements Figure 2 10 Measuring forward bias of diode Red Lead Black Lead ...

Page 63: ...Making Measurements 2 Keysight U1251B U1252B User s and Service Guide 41 Figure 2 11 Measuring reverse bias of diode Red Lead Black Lead ...

Page 64: ...uring time in order to obtain the correct capacitance value For measuring smaller capacitance values press with the test leads open to subtract any residual capacitance from the meter or the leads Set up the multimeter as shown in Figure 2 12 Use the red probe lead on the positive terminal of the capacitor and the black probe lead on the negative terminal and read the display CAUTION Disconnect th...

Page 65: ...Making Measurements 2 Keysight U1251B U1252B User s and Service Guide 43 Figure 2 12 Capacitance measurements Red Lead Black Lead ...

Page 66: ...asurement 2 Connect the miniture thermal probe into the non compensation transfer adapter as shown in Figure 2 13 3 Connect the thermal probe with the adapter into the meter input terminals as shown in Figure 2 14 4 For best performance place the meter in the operating environment for at least one hour to stabilize the unit to environment temperatures 5 Clean the measurement surface and make sure ...

Page 67: ...pensation adapter to see the temperature variation of the thermocouple sensor The 0 C compensation adapter assists in measuring the relative temperature immediately Figure 2 13 Connecting the thermal probe into the non compensation transfer adapater Figure 2 14 Connecting the probe with adapter into the multimeter ...

Page 68: ...owing 1 Press to select 0 C compensation This gives a quick measurement of the relative temperature 2 Avoid contact between the thermocouple probe and the measurement surface 3 After a constant reading is obtained press to set the reading as the relative reference temperature 4 Touch the measurement surface with the thermocouple probe 5 Read the display for the relative temperature ...

Page 69: ...Making Measurements 2 Keysight U1251B U1252B User s and Service Guide 47 Figure 2 15 Surface temperature measurement ...

Page 70: ...your safety please be aware of this alert Input warning The meter sounds an alert beep when the test lead is inserted into the A input terminal but the rotary switch is not set to the corresponding mA A location The primary display indicates a flashing A Err until the test lead is removed from the A input terminal Refer to Figure 2 16 Figure 2 16 Input terminal warning WARNING For your safety look...

Page 71: ...er sounds an alert beep when the terminal detects a voltage level of more than 5 V and the rotary switch is not set to the corresponding location The primary display indicates a flashing Ch Err until the lead is removed from the input terminal Refer to Figure 2 17 below Figure 2 17 Charge terminal alert ...

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Page 73: ...r Hold 54 Refresh Hold 55 Null Relative 57 Decibel Display 59 1 ms Peak Hold 61 Data Logging 63 Manual logging 63 Interval logging 65 Reviewing logged data 67 Square Wave Output for U1252B 69 Remote Communication 73 This chapter contains information on the functions and features that are available for the U1251B and U1252B digital multimeter ...

Page 74: ...ime is exceeded OL is shown on the display 1 Press for more than 1 second to enter Dynamic Recording mode The meter is now in continuous mode or non data hold non trigger mode MAXMINAVG and present value of measurement are displayed The multimeter will beep when a new maximum or minimum value is recorded 2 Press to cycle through maximum minimum average and present readings The MAX MIN AVG and MAXM...

Page 75: ...nd Service Guide 53 Figure 3 1 Dynamic recording mode operation Press Max Min for 1 sec Press Max Min for 1 sec or press for 1 sec Press Max Min for 1 sec Press Max Min for 1 sec Press Max Min or press for 1 sec or press for 1 sec Press Max Min Press Max Min ...

Page 76: ...ue 1 Press to freeze the displayed value and to enter the manual trigger mode TRIG is displayed 2 Press again to freeze the next value being measured TRIG flashes before the new value is updated on the display 3 Press and hold or for more than 1 second to quit the data hold function Figure 3 2 Data hold mode operation Measurement update Press or press for 1 sec Press Press ...

Page 77: ... with a new measured value and emit a tone as a reminder 1 Press to enter Refresh Hold mode The present value will be held and the symbol will appear 2 It will be ready to hold a new measured value once the variation of measured values exceeds the variation count setting While the multimeter is waiting for a new stable value the symbol will flash 3 The symbol will stop flashing once the new measur...

Page 78: ... Press Variation counts Measurement is to return Press NOTE For voltage and current measurements the holding value will not be updated if the reading is below 500 counts For resistance and diode measurements the holding value will not be updated if the reading is in OL open state The holding value may not be updated when the reading does not reach a stable state for all measurements ...

Page 79: ...d reference value NULL flashes for 3 seconds before the display returns to zero 3 To exit this mode press while NULL is flashing on the display NOTE Null can be set for both auto and manual range settings but not in the event of an overload When taking a resistance measurement and the meter reads a non zero value due to the presence of test leads use the Null function to adjust the display to zero...

Page 80: ...58 Keysight U1251B U1252B User s and Service Guide 3 Features and Functions Figure 3 4 Null relative mode operation Press Press as NULL is flashing on the display Press Auto return after 3 seconds Flash ...

Page 81: ... mode The default value is 50 Ω The decibel of voltage is calculated with respect to 1 V The equation for the voltage measurement is as follows dBV 20 log10 Vin 1 At the or rotary switch position press to scroll to the dBm measurement on the primary display The secondary display indicates the AC voltage measurement 2 Press for more than 1 second to exit this mode NOTE If the rotary switch is at th...

Page 82: ...Guide 3 Features and Functions Figure 3 5 dBm dBV display mode operation Press Press Press Press Press for 1 sec Press for 1 sec Only when rotary switch is at position Only when rotary switch is at position Press Press for 1 sec Press Press Press ...

Page 83: ...ak value True RMS value 1 Press for more than 1 second to toggle 1 ms Peak Hold mode ON OFF 2 Press to scroll through maximum and minimum peak readings MAX indicates the maximum peak while MIN indicates the minimum peak 3 Press and hold or for more than 1 second to exit this mode 4 According to the measurements shown in Table 3 6 on page 62 the crest Factor will be 2 5048 1 768 1 416 NOTE If the r...

Page 84: ...62 Keysight U1251B U1252B User s and Service Guide 3 Features and Functions Figure 3 6 1 ms peak hold mode operation Press for 1 sec Press Press Start to capture Press Start to capture Press ...

Page 85: ...nual logging Firstly ensure that manual hand logging is specified in Setup mode 1 Press for more than 1 second to store the present value and function on the primary display to the non volatile memory The and the logging index will be indicated The logging index flashes on the secondary display for 3 seconds before returning to normal display 2 Press and hold again for the next value that you woul...

Page 86: ...al logging mode operation Figure 3 8 Full Log Press for 1 sec Press for 1 sec Auto return after 3 seconds NOTE The maximum data that can be stored is 100 entries When the 100 entries are filled the secondary display indicates FULL as shown in Figure 3 8 Auto return after 3 seconds Press for 1 sec ...

Page 87: ...o the non volatile memory The and the logging index will be indicated The readings are automatically saved into the permanent memory at intervals set using the Setup mode 2 Press for more than 1 second to exit this mode NOTE The maximum data that can be stored is 200 entries When the 200 entries are filled FULL is indicated on the secondary display NOTE When interval automatic logging is enabled a...

Page 88: ...1B U1252B User s and Service Guide 3 Features and Functions Figure 3 9 Interval Automatic logging mode operation Press for 1 sec Press for 1 sec Press for 1 sec First interval Last interval Last 1 interval Stop logging ...

Page 89: ... manual and interval automatic logging review mode 3 Press to ascend or to descend through the logged data Press to select the first record and press to select the last record for quick navigation 4 Press for more than 1 second at the respective Log Review mode to clear logged data 5 Press for more than 1 second to exit mode 6 During the data review in either manual or interval logging mode press ...

Page 90: ...tions Figure 3 10 Log review mode operation Press View for 1 sec Press View Press Press Press Press Press Press Press Press Press Press Press Press Press Log for 1 sec to clear all manual logs Press Log for 1 sec to clear all interval logs Press View Press View Press View ...

Page 91: ...requency input devices 1 Turn the rotary switch to position The default display setting is 600 Hz on the secondary display and 50 duty cycle on the primary display 2 Press or to scroll through the available frequencies choose from the available 28 frequencies 3 Press to select the duty cycle on the primary display 4 Press or to adjust the duty cycle Duty cycle can be set for 256 steps and each ste...

Page 92: ...tment for square wave output 5 Press to select the pulse width ms on the primary display 6 Press or to adjust the pulse width The pulse width can be set for 256 steps and each step is 1 256 x Frequency The display range automatically adjusts in the range of 9 9999 9999 9 ms Press Press Press Press Set Hz ...

Page 93: ...Features and Functions 3 Keysight U1251B U1252B User s and Service Guide 71 Figure 3 12 Duty cycle adjustment for square wave output Press Press Press Press ...

Page 94: ...72 Keysight U1251B U1252B User s and Service Guide 3 Features and Functions Figure 3 13 Pulse width adjustment for square wave output Press Press Press Press ...

Page 95: ... To use this feature you require the optional IR USB cable to be used with an application software downloadable from the Keysight Web site For details on performing PC to meter remote communication click on Help after launching the Keysight GUI Data Logger Software or refer to the GUI Data Logger Quick Start Guide U1251 90023 for more information Figure 3 14 Cable connection for remote communicati...

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Page 97: ...imum Frequency Measurement 84 Setting Temperature Unit 85 Setting Auto Power Saving Mode 87 Setting Percentage Scale Readout 89 Setting Beep Frequency 90 Setting Backlight Timer 91 Setting Baud Rate 92 Setting Parity Check 93 Setting Data Bit 94 Setting Echo Mode 95 Setting Print Mode 96 Returning to Default Factory Settings 97 Setting the Battery Voltage 98 Setting the Filter 99 This chapter show...

Page 98: ...osition To change a menu item setting in Setup mode perform the following steps 1 Press or to scroll through the menu items 2 Press or to scroll through the available settings See Table 4 1 Available setting options in Setup mode for details of available options 3 Press to save changes These parameters will remain in the non volatile memory 4 Press for more than 1 second to exit Setup mode NOTE Wh...

Page 99: ...voltage to either 7 2 V or 8 4 V 7 2 V rESEt Reset dEFAU Enables the reset of factory settings by pressing and holding for more than 1 second dEFAU Print Print On OFF Enables auto send of data to the PC continu ously when set to On OFF ECHO Echo On OFF Enables the return of characters to the PC when set to On OFF dAtAb Data bits 7 bit 8 bit Sets the data bit length for the remote commu nication re...

Page 100: ...nd PErnt Percentage scale 0 20 mA 4 20 mA Sets the scale read out 4 20 mA APF Auto power off 1 99 m 2 Sets the timer for auto power off 10 m OFF Disables auto power off FrEq Minimum frequency that can be measured 0 5 Hz 1 Hz 2 Hz 5 Hz Sets the minimum fre quency that can be measured 0 5 Hz rEF Reference impedance for dBm measurement 1 9999 Ω 2 Sets the reference impedance for dBm measurement 50 Ω ...

Page 101: ...asurement to F d FC Sets the temperature measurement to F but pressing swaps display to C d C Sets the temperature measurement to C Notes for setting options in Setup mode 1 This is the first option displayed once the user enters Setup mode 2 For b Lit APF rEF and d LoG menu items the user can select the digit to be adjusted by pressing 3 This menu option is only available for the U1252B 4 To view...

Page 102: ...d mode manual trigger by key or bus via the remote control 2 Set the variation count within the 100 1000 range to enable the Refresh Hold mode auto trigger When the variation of the measuring value exceeds the setting of the variation count the Refresh Hold will be ready to trigger Figure 4 1 Data hold Refresh hold setup Press Press Press Press Press ...

Page 103: ...to enable the manual data logging mode 2 Set the interval within 0001 9999 seconds to enable interval automatic data logging mode 3 Press and hold or for more than 1 second to switch between manual and interval data logging setup Figure 4 2 Data logging setup Press Press Press Press to set interval Press or Press 1 second ...

Page 104: ... Guide 4 Changing The Default Setting Setting Thermocouple Types U1252B only The thermocouple sensor types that can be selected are type K default or type J Press or to switch between the J and the K type Figure 4 3 Thermocouple type setup Press ...

Page 105: ...51B U1252B User s and Service Guide 83 Setting Reference Impedance for dBm Measurement The reference impedance can be set from 1 to 9999 W The default value is 50 W Figure 4 4 Reference impedance for dBm measurement setup Press Press Press Press ...

Page 106: ...tting Setting Minimum Frequency Measurement The minimum frequency setup influences the measuring rates for frequency duty cycle and pulse width The typical measuring rate is based on the minimum frequency of 1 Hz Figure 4 5 Minimum frequency setup Press Press Press Press Press ...

Page 107: ...ature Unit Four combination displays are available Celsius only C on primary display single display setting Celsius Fahrenheit d CF and Fahrenheit Celsius d FC dual display setting Fahrenheit only F on primary display single display setting NOTE Primary Secondary Display can be swapped by pressing ...

Page 108: ...86 Keysight U1251B U1252B User s and Service Guide 4 Changing The Default Setting Figure 4 6 Temperature unit setup Press Press Press Press Press ...

Page 109: ...etting Auto Power Saving Mode The timer for APF Auto Power OFF can be set for the range of 1 99 minutes To activate the meter after it has auto powered off turn the rotary switch to the OFF position Then turn it back on again will be shown on the display during subsequent measurements ...

Page 110: ...88 Keysight U1251B U1252B User s and Service Guide 4 Changing The Default Setting Figure 4 7 Auto power saving setup Press Press Press Press Press ...

Page 111: ...ide 89 Setting Percentage Scale Readout This setting converts the DC current measuring display to percentage scale readout 4 20 mA or 0 20 mA as proportional to 0 100 The 25 scale readout represents DC 8 mA at 4 20 mA and DC 5 mA at 0 20 mA Figure 4 8 scale readout setup Press ...

Page 112: ...User s and Service Guide 4 Changing The Default Setting Setting Beep Frequency The driving frequency can be set to 2400 1200 600 or 300Hz OFF disables the beep Figure 4 9 Beep frequency setup Press Press Press Press Press Press ...

Page 113: ...er s and Service Guide 91 Setting Backlight Timer The timer can be set to 1 99 seconds The backlight will turn off automatically after the set period 0FF disables turning off backlit automatically Figure 4 10 Backlit timer setup Press Press Press Press Press ...

Page 114: ...and Service Guide 4 Changing The Default Setting Setting Baud Rate Select the baud rate for remote control The available settings are 2400 4800 9600 and 19200 Hz Figure 4 11 Baud rate setup remote control Press Press Press Press Press ...

Page 115: ...lt Setting 4 Keysight U1251B U1252B User s and Service Guide 93 Setting Parity Check Select the parity check for remote control It can be set to none even or odd bit Figure 4 12 Parity check setup Press Press Press Press ...

Page 116: ...U1251B U1252B User s and Service Guide 4 Changing The Default Setting Setting Data Bit Select the data bit for remote control It can be set to either 8 or 7 bits Figure 4 13 Data bit setup for remote control Press ...

Page 117: ... U1251B U1252B User s and Service Guide 95 Setting Echo Mode Echo ON enables the return of characters to the PC in remote communication Echo OFF disables the return of characters to the PC Figure 4 14 Echo mode setup for remote control Press ...

Page 118: ...ON enables the printing of measured data to the PC when the measuring cycle is completed In this mode the meter automatically sends the newest data to the host continuously but does not accept any commands from the host flashes during the Print operation Figure 4 15 Print mode setup for remote control Press ...

Page 119: ...rning to Default Factory Settings Press for more than 1 second to reset to the default factory settings all menu options except the Temperature setting The Reset menu item automatically reverts to Refresh Hold menu item after reset has taken place Figure 4 16 Reset setup Press for 1 sec ...

Page 120: ...t U1251B U1252B User s and Service Guide 4 Changing The Default Setting Setting the Battery Voltage Battery type for the multimeter can be set to either 7 2 V or 8 4 V Figure 4 17 Battery voltage selection Press ...

Page 121: ...ng paths The DC filter is set to ON by default Figure 4 18 DC filter Press NOTE When the DC filter is enabled the measurement speed may decrease during DC voltage measurement During AC or Hz measurement on primary or secondary display DC filter will be automatically disabled For firmware version 2 17 and below the Filter function is switched off by default ...

Page 122: ...User s and Service Guide 4 Changing The Default Setting Table 4 2 Filter defaults Parameter Firmware version 1 Default setting FiLtEr 2 17 and below oFF 2 18 and above oN 1 Firmware is factory installed and not field upgradeable ...

Page 123: ... maintenance 102 Battery replacement 102 Storage considerations 104 Charging the battery 105 Fuse checking procedure 112 Replacing the fuse 114 Troubleshooting 116 Replaceable Parts 117 To order replaceable parts 117 This chapter will go through how to troubleshoot the handheld digital multimeter if any problems arise ...

Page 124: ... alcohol Battery replacement The meter is powered by a 9 V Ni MH rechargeable battery 8 4 V nominal voltage Use only the specified type refer to Figure 5 1 To ensure that the correct battery type is used replace the battery immediately when the low battery sign flashes If your meter has the rechargeable battery type refer to the section Charging the battery on page 105 The steps for battery replac...

Page 125: ...position counterclockwise 2 Slide down the battery cover 3 Lift the battery cover up 4 Replace the specified battery 5 Reverse the above steps to close the cover NOTE List of compatible batteries for the Keysight U1251B 9 V Alkaline non chargeable battery ANSI NEDA 1604A or IEC 6LR61 9 V Carbon zinc non chargeable battery ANSI NEDA 1604D or IEC6F22 ...

Page 126: ...U1252B 9 V size 300 mAH Ni MH rechargeable battery 7 2 V nominal voltage 9 V size 250 mAH Ni MH rechargeable battery 8 4 V nominal voltage 9 V Alkaline non chargeable battery ANSI NEDA 1604A or IEC 6LR61 9 V Carbon zinc non chargeable battery ANSI NEDA 1604D or IEC6F22 CAUTION To avoid instrument damage from battery leakage Always remove dead batteries immediately It is recommended that the batter...

Page 127: ... or by reverse polarity in any subjects Make sure the battery is the rechargeable type before charging it Never rotate the rotary switch when the battery is being charged as DC at 24 V is being applied to the charging terminals CAUTION Do not rotate the rotary switch from position when charging the battery Perform battery charging only with a 9 V Ni MH rechargeable battery 7 2 V nominal voltage or...

Page 128: ...n order to set the 24 V DC output and the over current limitation to a value more than 0 5 A Ensure that the polarity of the connection is correct 4 The primary display will show bAt and the SbY will be shown on the secondary display and a short beep will sound to remind you whether you need to charge the battery Press SHIFT to start charging the battery or the meter will automatically start the s...

Page 129: ...display as trickle 5 After pressing SHIFT or when the self test starts the meter performs a self test to check if the battery in the meter is the rechargeable type The self test takes about 2 to 3 minutes Avoid pressing any button during the self test A message is diplayed as shown in Figure 5 3 ...

Page 130: ...ight U1251B U1252B User s and Service Guide 5 Maintenance Figure 5 3 Self test Table 5 2 Error messages Error Error message OL 1 No battery inside 2 Faulty battery 3 Battery is fully charged Error Error message ...

Page 131: ...If charging battery more than 12 V or less than 5 V 2 In 3 minutes if the battery voltage does not go upwards then charge error Table 5 2 Error messages continued NOTE If the OL message appears while the battery is inside do not charge the battery If the C Err message appears check if the battery is the specified type Use the battery as specified in this manual Ensure that the battery is the corre...

Page 132: ...once charging is completed The trickle charging current is provided to maintain the battery capacity The flashing signs of and appear to show the trickle state 8 Remove the DC adapter when the C End message appears on the secondary display Do not turn the rotary switch before removing the adapter from the terminals Figure 5 5 Charge end and trickle state ...

Page 133: ...Maintenance 5 Keysight U1251B U1252B User s and Service Guide 111 Figure 5 6 Battery charging procedure Press to start charge Error Full Error Empty Battery can be charged Fully charged Error Error ...

Page 134: ...hat you check the fuses of the multimeter before using it Follow the instructions below to test the fuses inside the multimeter Refer to Figure 5 8 for the respective positions of Fuse 1 and Fuse 2 1 Set the rotary switch to 2 Connect the red test lead to the input terminal Figure 5 7 Fuse checking procedures ...

Page 135: ... the tip of the test probe on the right half of input terminal Ensure that the probe tip touches the metal inside the input terminal 5 Observe the reading on the instrument s display Refer to Table 5 3 below for the possible readings that could appear 6 Replace the fuse when OL is displayed Table 5 3 Measurement readings for fuse checking Current input terminal Fuse Fuse rating Fuse OK approximate...

Page 136: ...the fuse 4 Loosen the three screws on the bottom case and remove the cover 5 Loosen the two screws on the top corners to lift the circuit board 6 Gently remove the defective fuse by prying one end of the fuse loose and removing it out of the fuse bracket 7 Replace with a new fuse of the same size and rating Make sure the new fuse is centered in the fuse holder 8 Ensure that the rotary switch on th...

Page 137: ...2B User s and Service Guide 115 Figure 5 8 Fuse replacement Table 5 4 Fuse specifications Fuse Keysight part number Rating Size Type 1 2110 1400 440mA 1000V 10 mm x 35 mm Fast blow Fuse 2 2110 1402 11A 1000V 10 mm x 38 mm Fuse 1 Fuse 2 ...

Page 138: ...k the fuse No charging indication 1 Check 440 mA fuse Check the external adapter to verify if the output is DC 24 V and the adapter is plugged into the charging terminals completely Line power voltage 100 V 240 V AC 50 Hz 60 Hz Battery life very short after full charge Battery not able to charge after prolong storage period Check if the correct rechargeable battery is used Check if the correct nom...

Page 139: ... includes a brief description of each part with applicable Keysight part number To order replaceable parts You can order replaceable parts from Keysight using the Keysight part number Note that not all parts listed are available as field replaceable parts To order replaceable parts from Keysight do the following 1 Contact your nearest Keysight Sales Office or Service Center 2 Identify the parts by...

Page 140: ...118 Keysight U1251B U1252B User s and Service Guide 5 Maintenance THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...

Page 141: ...t test 123 Testing the display 123 Current terminal test 124 Charge terminal alert test 125 Test Considerations 126 Calibration Security 127 Performance Verification Tests 128 Unsecuring the instrument for calibration 136 Calibration Process 139 Using the front panel for adjustments 140 Adjustments Consideration 141 Valid adjustment input values 142 Adjustment Procedure 143 Finishing the Adjustmen...

Page 142: ...calibration This instrument features closed case electronic calibration No internal mechanical adjustments are required The instrument calculates correction factors based upon the input reference value you set The new correction factors are stored in the nonvolatile memory until the next calibration adjustment is performed The nonvolatile EEPROM calibration memory is retained even when the power i...

Page 143: ...s are only guaranteed within the period stated from the last adjustment Keysight recommends that readjustment should be performed during the calibration process for best performance This will ensure that the U1251B U1252B will remain within the specifications for the next calibration interval This criterion for the re adjustment provides the best long term stability Performance data are measured d...

Page 144: ...ommended equipment Recommended accuracy requirements DC Voltage Fluke 5520A 1 5 instrument 1 year spec DC Current Fluke 5520A 1 5 instrument 1 year spec Resistance Fluke 5520A 1 5 instrument 1 year spec AC Voltage Fluke 5520A 1 5 instrument 1 year spec AC Current Fluke 5520A 1 5 instrument 1 year spec Frequency Keysight 33250A 1 5 instrument 1 year spec Capacitance Fluke 5520A 1 5 instrument 1 yea...

Page 145: ...ity of the instrument Repair is required if the instrument fails the Basic Operating Test Backlit test Press the Bat button to test the backlight It will momentarily toggle backlit ON and OFF Testing the display Press the Hold button and turn on the meter to view all segments of the display Compare the display with the example in Table 6 1 Figure 6 1 LCD display ...

Page 146: ...operly The meter sounds an alert beep when the test lead is inserted into the A terminal but the rotary switch is not set to mA A function The primary display will indicate A Err as shown in Figure 6 2 The primary display will keep flash ing unless the test lead is removed from A terminal Figure 6 2 Input warning NOTE Before conducting this test make sure the beep function is not disabled in setup...

Page 147: ...properly The meter sounds an alert when the terminal detects a voltage level of more than 5 V and the rotary switch is not set to the position The meter sounds an alert beep and the primary display flashes the Ch Err until the lead is removed from the terminal Figure 6 3 Charge terminal alert NOTE Before conducting this test make sure the beep function is not disabled at setup ...

Page 148: ...s should comply with the following recommendations Ensure that the calibration ambient temperature is stable and is between 18 C and 28 C Ideally the calibration should be performed at 23 C 1 C Ensure that the ambient relative humidity is less than 80 Allow a warm up period of five minutes Use shielded twisted pair PTFE insulated cables to reduce settling and noise errors Keep the input cables as ...

Page 149: ...y code see Unsecuring the instrument for calibration on page 136 The security code is set to 1234 when the instrument is shipped from the factory This code is stored in nonvolatile memory and does not change when power is turned off The security code may contain up to 4 numeric characters NOTE You can unsecure the instrument from the front panel The security code can only be changed from the front...

Page 150: ...ument s specifications listed in the U1251B U1252B Data Sheet The performance verification tests are recommended as acceptance tests when you first receive the instrument The acceptance test results should be compared against the one year test limits After acceptance you should repeat the performance verification tests at every calibration interval NOTE Make sure you have read the Test Considerati...

Page 151: ...5 V 5 V 1 kHz 32 5 mV 22 5 mV 4 5 V 10 kHz 169 5 mV 71 5 mV 4 5 V 20 kHz N A 169 5 mV 4 5 V 30 kHz 169 5 mV N A 4 5 V 100 kHz N A 169 5 mV 50 V 50 V 1 kHz 325 mV 225 mV 45 V 10 kHz 1 695 V 715 mV 45 V 20 kHz N A 1 695 V 45 V 30 kHz 1 695 V N A 45 V 100 kHz N A 1 695 V 500 V 500 V 1 kHz 3 25 V 2 25 V 1000 V 1000 V 1 kHz 10 V 8 0 V 2 Press button to go to frequency mode 9 9999 kHz 0 48 V 1 kHz 500 m...

Page 152: ... mV 200 mV 1000 V 1000 V 800 mV 800 mV 5 Press button to go to the 5 V 5 V 1 kHz N A 22 5 mV V mode 1 5 V 10 kHz N A 79 0 mV 4 5 V 20 kHz N A 169 5 mV 4 5 V 100 kHz N A 169 5 mV 50 V 50 V 1 kHz N A 225 mV 50 V 10 kHz N A 790 mV 45 V 20 kHz N A 1 695 V 45 V 100 kHz N A 1 695 V 500 V 500 V 1 kHz N A 2 25 V 1000 V 1000 V 1 kHz N A 8 0 V 6 Turn the rotary switch to the position 50 mV 50 mV 75 μV 2 75 ...

Page 153: ... 24 mV 50 mV 10 kHz 0 86 mV 0 415 mV 45 mV 20 kHz N A 1 695 mV 50 mV 30 kHz 0 86 mV N A 45 mV 100 kHz N A 1 695 mV 500 mV 500 mV 45 Hz 3 25 mV 2 25 mV 500 mV 1 kHz 3 25 mV 2 25 mV 500 mV 10 kHz 8 6 mV 4 15 mV 450 mV 20 kHz N A 16 95 mV 500 mV 30 kHz 8 6 mV N A 450 mV 100 kHz N A 16 95 mV 1000 mV 1000 mV 1 kHz 8 5 mV 6 5 mV 1000 mV 10 kHz 47 mV 11 5 mV 1000 mV 20 kHz N A 47 0 mV 1000 mV 30 kHz 47 m...

Page 154: ...on to go to ns mode 500 nS 5 50 nS 0 7 nS 0 6 nS 10 Turn the rotary switch to the Hz position for model U1252B to position for model U1251B Diode 1 V 1 mV 1 mV 33250A Output 11 Press button to go to frequency counter mode 6 999 99 kHz 200 mVrms 100 kHz N A 52 Hz 12 Press button to go to frequency counter mode divide by 100 99 999 MHz 600 mVrms 10 MHz N A 5 2 kHz 5520A Output 13 Turn the rotary swi...

Page 155: ...A 9 0 3 μA 9 5000 μA 5000 μA 5 5 μA 9 3 μA 9 16 Press button to go to µA mode 1 500 μA 500 μA 1 kHz 4 2 μA 3 7 μA 500 μA 20 kHz 15 8 μA 3 95 μA 5000 μA 5000 μA 1 kHz 42 μA 37 0 μA 5000 μA 20 kHz 0 156 mA 39 5 μA 17 Turn the rotary switch to the position 50 mA 50 mA 0 105 mA 9 80 μA 9 440 mA 400 mA 0 93 mA 9 0 65 mA 9 18 Press button to go to mA mode 1 50 mA 50 mA 1 kHz 0 42 mA 0 37 mA 50 mA 20 kHz...

Page 156: ...l for minimizing measurement errors 7 Use the Null mode to zero residual 8 The accuracy does not include the tolerance of the thermocouple probe The thermal sensor plugged into the meter should be placed in the operating enviroment for at least an hour Use the Null function to reduce the thermal effect 9 Always use relative function to zero the thermal effect with open test lead before measuring t...

Page 157: ...measure the signal greater than 10 A 20 A for 30 seconds maximum After measured current for 10 A to cool down the meter for 2 times of measuring time you applied before low current measurement 12 For signal frequency greater than 1 kHz additional 0 1 per kHz to be added to accuracy 13 Ensure that the ambient temperature is stable within 1 ºC Make sure that the multimeter is placed in a controlled ...

Page 158: ...ecurity code is stored in nonvolatile memory and does not change when power is off To Unsecure the Instrument from the Front Panel 4 Turn the rotary switch to 5 Press and button simultaneously to enter the Calibration Security Code entry mode 6 The primary display shows 5555 and the secondary display show SECUr 7 Use the editing keys and to step each character in the code Use the and to select eac...

Page 159: ...1 second to enter the Calibration Security Code setting mode 2 The factory default calibration security code 1234 will be displayed on the primary display 3 Use the editing keys and to step each character in the code 4 Use the and to change each character in the code 5 Press Save to store the new calibration security code 6 If the new calibration security code has been successfully stored the seco...

Page 160: ...Default Security Code mode The secondary display shows SEr no and the primary display shows 5555 5 Use the editing keys and to step each character in the code 6 Use and to select each character 7 Set the code same as the last 4 digits of the instrument s serial number 8 Press Save to confirm the entry 9 If the 4 digits entered are correct the secondary display will show PASS Now you can use 1234 a...

Page 161: ...he verification tests to characterize the instrument incoming data 3 Unsecure the instrument for calibration see Calibration Security on page 127 4 Perform the adjustment procedures see Adjustments Consideration on page 141 5 Secure the instrument against calibration 6 Note the new security code and calibration count in the instrument s maintenance records NOTE Make sure to quit the Adjustment Mod...

Page 162: ... instrument for calibration on page 136 or To unsecure the instrument without the security code on page 138 Once unsecured the reference value will be indicated on the primary display Entering Adjustment Values Use the following adjustment procedure to enter an input calibration value from the front panel 1 Use the edit keys and to select each digit in the primary display 2 Use the and the arrow k...

Page 163: ...est leads to the calibrator and handheld multimeter It is recommended to wait for one minute before you begin the calibration after connecting the test leads 4 During ambient temperature adjustment be sure to turn on the instrument for at least 1 hour with the K type thermocouple connected between the instrument and the calibration source NOTE After each adjustment the secondary display briefly sh...

Page 164: ...50 V 500 V 1000 V 0 9 to 1 1 x Full Scale for U1251B 5 V 50 V 500 V 1000 V 0 9 to 1 1 x Full Scale for U1252B 5 V 50 V 500 V 1000 V 0 9 to 1 1 x Full Scale 50 mV 500 mV 1000 mV 0 9 to 1 1 x Full Scale 500 µA 5000 µA 0 9 to 1 1 x Full Scale 50 mA 440 mA 5 A 10 A 0 9 to 1 1 x Full Scale Ω 500 Ω 5kΩ 50 kΩ 500 kΩ 5MΩ 50 MΩ 0 9 to 1 1 x Full Scale Diode 0 9 to 1 1 x Full Scale 10 nF 100 nF 1000 nF 10 µ...

Page 165: ...l show the reference value of the Cal Item 4 Configure each Cal Item 5 Use the and the arrow keys to select the Cal Range 6 Apply the input signal shown in the Input column of the table The bar graph will display the Input reading There is no bar graph display for temperature adjustment 7 Enter the actual applied input see Entering Adjustment Values on page 140 8 Press to start the adjustment The ...

Page 166: ...ndicated by a long beep and a calibration error number appears in the secondary display The primary display remains at the current Cal Item Check the input value range function and entered adjustment value to fix the problem Repeat the adjustment procedure 9 Repeat steps 1 through 8 for each adjustment point 10 Verify the adjustments using the Performance Verification Tests on page 128 and Table ...

Page 167: ... V 20 kHz 3 0000 V 3 0000 V 50 V 3 V 1 kHz 03 000 V 03 000 V 30 V 1 kHz 30 000 V 30 000 V 30 V 20 kHz 3 0000 V 30 000 V 500 V 30 V 1 kHz 030 00 V 030 00 V 300 V 1 kHz 300 00 V 300 00 V 300 V 20 kHz 3 0000 V 300 00 V 1000 V 30 V 1 kHz 0030 0 V 0030 0 V 300 V 1 kHz 0300 0 V 0300 0 V 300 V 20 kHz 3 0000 V 0300 0 V 2 Turn the rotary switch to position for model U1252B to position for model U1251B Shor...

Page 168: ...0 V 3 V 1 kHz N A 03 000 V 30 V 1 kHz N A 30 000 V 30 V 20 kHz N A 30 000 V 500 V 30 V 1 kHz N A 030 00 V 300 V 1 kHz N A 300 00 V 300 V 20 kHz N A 300 00 V 1000 V 30 V 1 kHz N A 0030 0 V 300 V 1 kHz N A 0300 0 V 300 V 20 kHz N A 0300 0 V 4 Turn the rotary switch to the position Short Dual banana plug with copper wire short between 2 terminals SHort SHort 50 mV 30 mV 30 000 mV 30 000 mV 500 mV 300...

Page 169: ...00 mV 300 mV 20 kHz 30 000 mV 300 00 mV 1000 mV 30 mV 1 kHz 0030 0 mV 0030 0 mV 1000 mV 1 kHz 1000 0 mV 1000 0 mV 1000 mV 20 kHz 30 000 mV 1000 0 mV 6 Turn the rotary switch to the W position 1 Short Dual Banana Plug with copper wire short between 2 terminals SHort SHort 50 MW Input terminal open remove any test leads and Short Plugs from the input terminal oPEn oPEn 10 MW 10 000 MW 10 000 MW 5 MW...

Page 170: ... Plugs from the input terminal oPEn oPEn 10 nF 3 nF 03 000 nF 03 000 nF 10 nF 10 000 nF 10 000 nF 100 nF 10 nF 010 00 nF 010 00 nF 100 nF 100 00 nF 100 00 nF 1000 nF 100 nF 0100 0 nF 0100 0 nF 1000 nF 1000 0 nF 1000 0 nF 10 µF 10 µF 10 000 µF 10 000 µF 100 µF 100 µF 100 00 µF 100 00 µF 1000 µF 1000 µF 1000 0 µF 1000 0 µF 10 mF 10 mF 10 000 mF 10 000 mF 9 Press button to go to mode 2 N A 0 ºC 0000 ...

Page 171: ...nd COM terminal to A and COM terminal Caution Connect the calibrator to hanheld multimeter s A and COM terminals before applying 3A and 10A 5 A 3 A 3 0000 A 3 0000 A 10 A 10 A 10 000 A 10 000 A Move the test lead from A and COM terminal to uA mA and COM terminal 13 Press button to go to 50 mA 3 mA 1 kHz 03 000 mA 03 000 mA mA mode 30 mA 1 kHz 30 000 mA 30 000 mA 440 mA 30 mA 1 kHz 030 00 mA 030 00...

Page 172: ...ases by one for each calibration point and a complete calibration will increase the value by many counts The calibration count increments up to a maximum of 65535 after which it is set at 0 The calibration count can be read from the front panel after the instrument has been unsecured Use the following procedure to read the calibration count from the front panel Notes for adjustment table 1 Be sure...

Page 173: ...te failures that may occur during a calibration Table 6 5 Calibration error codes and their respective meanings Error Code Description 200 Calibration error Calibration mode is secured 002 Calibration error Secure code invalid 003 Calibration error Serial number code invalid 004 Calibration error Calibration aborted 005 Calibration error Value out of range 006 Calibration error Signal measurement ...

Page 174: ...Performance Tests and Calibration 6 Keysight U1251B U1252B User s and Service Guide 152 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...

Page 175: ...2B 164 Capacitance Specifications 165 Temperature Specifications 165 Frequency Specifications 166 Duty Cycle and Pulse Width Specifications 167 Frequency Sensitivity Specifications 168 Peak Hold Specifications 169 Frequency Counter Specifications for U1252B 170 Square Wave Output for U1252B 171 Operating Specifications 172 Display update rate approximate 172 Input impedance 173 This chapter lists ...

Page 176: ...nt of 10 C to 30 C if the battery has been deep discharged a prolonged charging time is required in order for the battery to return to full capacity POWER CONSUMPTION 105 mVA 420 mVA with backlight usage maximum U1251B 165 mVA 480 mVA with backlight usage maximum U1252B DISPLAY Both primary and secondary displays are 5 digit liquit crystal display LCD with maximum reading of 50 000 counts Automati...

Page 177: ...6 1 2006 CISPR 11 2003 EN 55011 2007 Group 1 Class A Canada ICES 001 2004 Austrailia New Zealand AS NZS CISPR11 2004 SHOCK AND VIBRATION Tested to IEC EN 60068 2 TEMPERATURE COEFFICIENT 0 15 specified accuracy C from 20 C to 18 C or 28 C to 55 C COMMON MODE REJECTION RATIO CMRR 90 dB at DC 50 60 Hz 0 1 1 kΩ unbalanced NORMAL MODE REJECTION RATION NMRR 60 dB at 50 60 Hz 0 1 DIMENSIONS W H D 94 4 20...

Page 178: ...y_terms Three years for the product Three months for the product s standard accessories unless otherwise specified Please take note that for the product the warranty does not cover Damage from contamination Normal wear and tear of mechanical components Manuals fuses and standard disposable batteries CALIBRATION CYCLE One year ...

Page 179: ... that are directly connected to a low voltage installation For example measurements on household appliances portable tools and other similar equipment Measurement CAT III are measurements performed on building installations For example measurements on distribution boards circuit breakers wiring including cables bus bars junction boxes switches socket outlets within the fixed installation equipment...

Page 180: ...erferences or significant electrostatic charges are present Electrical Specifications DC Specifications Table 7 1 DC Accuracy of reading Number of Least Significant Digit Function Range Resolution Test Current Burden Voltage Accuracy U1251B U1252B Voltage 1 50 000 mV 0 001 mV 0 05 50 2 0 05 50 2 500 00 mV 0 01 mV 0 03 5 0 025 5 1000 0 mV 0 1 mV 5 0000 V 0 0001 V 50 000 V 0 001 V 500 00 V 0 01 V 0 ...

Page 181: ...000 MΩ 4 0 001 MΩ 187 nA 1 10 1 5 500 00 MΩ 4 0 01 MΩ 187 nA 3 10 200MΩ 8 10 200MΩ 500 00 nS 5 0 01 nS 187 nA 1 20 1 10 Notes for resistance specifications 3 The accuracy of 500 Ω and 5 kΩ is specified after Null function which is used to subtract the test lead resistance and the thermal effect 4 For the range of 50 Ω 500 MΩ the R H is specified for 60 5 The accuracy is specified for 50 nS and aft...

Page 182: ...te After measuring a current greater than 440 mA it is recommended that the meter be left to cool down for twice the length of measurement time used 8 Current can be measured up to 10 A continuously An additional 0 5 needs to be added to the specified accuracy if the signal measured is in the range of 10 A to 20 A 30 seconds maximum After measuring current 10 A leave the meter to cool down in swit...

Page 183: ... kHz 5 kHz to 30 kHz Voltage 1 2 50 000 mV 0 001 mV 1 60 0 6 40 1 0 40 1 6 60 500 00 mV 0 01 mV 1 60 0 6 25 1 0 40 1 6 60 1000 0 mV 0 1 mV 1 60 0 6 25 1 0 25 3 5 120 5 0000 V 0 0001 V 1 60 0 6 25 1 0 25 3 5 120 50 000 V 0 001 V 1 60 0 6 25 1 0 25 3 5 120 500 00 V 0 01 V 1 60 0 6 25 1 0 25 1000 0 V 0 1 V 1 60 0 6 40 1 0 40 Notes for U1251B AC voltage specifications 1 Input impedance Refer to Table ...

Page 184: ...for U1251B AC current specifications 1 AC mV V and AC µA mA A specifications are true RMS AC coupled valid from 5 to 100 of range The crest factor may be up to 3 at full scale up to 5 at half scale except for 1000 mV and 1000 V ranges where the crest factor is 1 5 at full scale and 3 at half scale 2 Input current 35 µArms 3 Current can be measured from 2 5 A up to 10 A continuously Add 0 5 to the ...

Page 185: ... Table 7 5 U1252B accuracy specifications of reading number of LSD for true RMS AC current Function Range Resolution Frequency 5 20 Hz 45 Hz 45 Hz 1 kHz 1 kHz 20 kHz 20 kHz 100 kHz 1 6 Current 5 500 00 µA 2 0 01 µA 1 0 20 0 7 20 0 75 20 5 80 5000 0 µA 0 1 µA 1 0 20 0 7 20 0 75 20 5 80 50 000 mA 0 001 mA 1 0 20 0 7 20 0 75 20 5 80 440 00 mA 0 01 mA 1 0 20 0 7 20 1 5 20 5 80 5 0000 A 0 0001 A 1 5 20...

Page 186: ...Hz and signal input 10 of range 3 counts of LSD per kHz 2 Input impedance Refer to Table 7 19 Table 7 7 U1252B true RMS ac dc current specifications Function Range Resolution Frequency 30 Hz 45 Hz 45 Hz 1 kHz 1 kHz 20 kHz Current 500 00 µA 1 0 01 µA 1 1 25 0 8 25 0 8 25 5000 0 µA 0 1 µA 1 1 25 0 8 25 0 8 25 50 000 mA 0 001 mA 1 2 25 0 9 25 0 9 25 440 00 mA 0 01 mA 1 2 25 0 9 25 0 9 25 5 0000 A 0 0...

Page 187: ...nF 10 000 µF 0 001 µF 100 00 µF 0 01 µF 1000 0 µF 0 1 µF 1 time sec 10 000 mF 0 001 mF 0 1 times sec 100 00 mF 0 01 mF 3 10 0 01 times sec Notes for capacitance specifications 1 Use the null operation to zero out residual offset before measuring the signal by opening the test leads Table 7 9 Temperature specifications Thermocouple Type Range Resolution Accuracy of reading No of Least Significant D...

Page 188: ...th the calibrator and the meter with an external reference without internal ambient compensation If both the calibrator and the meter are set with internal reference with internal ambient compensation deviation may show between the readings of the calibrator and the meter due to differences in ambient compensation between the calibrator and the meter 2 This thermocouple type is only available for ...

Page 189: ...curacy for duty cycle and pulse width is based on a 5 V square wave input into the DC 5 V range 2 For AC coupling the duty cycle range can be measured for signal frequency 20 Hz Pulse width 500 ms 0 01 ms 0 2 3 2000 ms 0 1 ms 0 2 3 Notes for pulse width specifications 1 The accuracy for duty cycle and pulse width is based on a 5 V square wave input into the DC 5 V range 2 Positive or negative puls...

Page 190: ...200 kHz 100 kHz 100 kHz 500 kHz 50 000 mV 10 mV 15 mV 10 mV 25 mV 10 mV 15 mV 10 mV 25 mV 500 00 mV 25 mV 35 mV 70 mV 150 mV 60 mV 70 mV 70 mV 150 mV 1000 0 mV 40 mV 50 mV 120 mV 300 mV 100 mV 150 mV 120 mV 300 mV 5 0000 V 0 25 V 0 5 V 0 3 V 1 2 V 0 5 V 1 25 V 100 Hz 0 6 V 0 6 V 1 5 V 50 000 V 2 5 V 5 V 3 V 5 V 5 V 6 V 6 V 15 V 500 00 V 25 V 30 V 100 kHz 50 V 60 V 1000 0 V 50 V 50 V 100 kHz 300 V ...

Page 191: ...rent measurements Input Range Minimum Sensitivity R M S sine wave 20 Hz 20 kHz 500 00 µA 100 µA 5000 0 µA 250 µA 50 000 mA 10 mA 440 00 mA 25 mA 5 0000 A 1 A 10 000 A 2 5 A Table 7 14 Peak hold specifications for dc voltage and current measurements Signal Width Accuracy For DC mV voltage current Single event 1 ms 2 400 for all ranges Repetitive 250 µs 2 1000 for all ranges ...

Page 192: ... specifications Range Resolution Accuracy of reading No of Least Significant Digit Sensitivity Min Input Frequency 9 9999 MHz 0 0001 MHz 0 002 5 20 MHz 400 mV R M S 1 MHz 99 99 MHz 0 001 MHz 600 mV R M S Notes for frequency counter specifications 1 All frequency counters are susceptible to error when measuring low voltage low frequency signals Shielding inputs from picking up external noise is cri...

Page 193: ...8 V 0 2 V Notes for square wave output specifications 1 Output impedance 3 5 kW maximum 2 The positive or negative pulse width must be greater than 50 µs for adjusting the duty cycle or the pulse width under different frequencies Otherwise the accuracy and the range will be different from the definition 3 For signal frequencies greater than 1 kHz add 0 1 per kHz to the accuracy 4 The accuracy for ...

Page 194: ... Times second AC V 7 AC V dB 7 DC V V or mV 7 AC V V or mV 7 AC DC V V or mV 2 Ω nS 14 Diode 14 Capacitance 4 100 µF DC A µA mA or A 7 AC A µA mA or A 7 AC DC A µA mA or A 2 Temperature 6 Frequency 1 10 Hz Duty cycle 0 5 10 Hz Pulse width 0 5 10 Hz NOTE The U1251B and U1252B handheld digital multimeter does not contain a realtime clock Only ONE sample per second can be logged ...

Page 195: ... 10 00 MΩ 500 00 V 10 00 MΩ 1000 0 V 10 00 MΩ AC DC Voltage 2 50 000 mV 10 00 MΩ 500 00 mV 10 00 MΩ 1000 0 mV 10 00 MΩ 5 0000 V 11 10 MΩ 10 MΩ 50 000 V 10 10 MΩ 10 MΩ 500 00 V 10 01 MΩ 10 MΩ 1000 0 V 10 001 MΩ 10 MΩ Notes for input impedance 1 For 5 V to 1000 V range the specified input impedance in parallel with 10 MΩ at dual display 2 The specified input impedance nominal in parallel with 100 pF...

Page 196: ...174 Keysight U1251B U1252B User s and Service Guide 7 Specifications THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK ...

Page 197: ...547 2111 Japan tel 81 426 56 7832 fax 81 426 56 7840 Korea tel 080 769 0800 fax 080 769 0900 Latin America tel 305 269 7500 Taiwan tel 0800 047 866 fax 0800 286 331 Other Asia Pacific Countries tel 65 6375 8100 fax 65 6755 0042 Or visit the Keysight World Wide Web at www keysight com find assist Product specifications and descriptions in this document are subject to change with out notice Always r...

Page 198: ...This information is subject to change without notice Keysight Technologies 2009 2015 Edition 15 April 3 2015 U1251 90036 U1251 90036 www keysight com ...

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