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Model 2750 Multimeter/Switch System Service Manual

Troubleshooting

4-7

Tr

oubleshooting

Microcontroller

U401 is the display board microcontroller that controls the display and interprets key data.
The microcontroller uses three internal peripheral I/O ports for the various control and
read functions.

Display data is serially transmitted to the microcontroller from the digital section via the
TXB line to the microcontroller RDI terminal. In a similar manner, key data is serially sent
back to the digital section through the RXB line via TDO. The 4MHz clock for the micro-
controller is generated by crystal Y401.

Display

DS401 is the display module, which can display up to 12 alphanumeric characters and
includes the various annunciators and five LED annunciators.

The display uses a common multiplexing scheme with each character refreshed in
sequence. U402 and U403 are the drivers for the display characters and annunciators.
Note that data for the drivers are serially transmitted from the microcontroller (MOSI and
PC1).

Filament voltage for the display is derived from the power supply transformer (F1 and
F2). The display drivers r37VDC and +5VDC, which are supplied by U144
(+5VD) and U101 (+37V).

Key matrix

The front panel keys (S401-S430) are organized into a row-column matrix to minimize the
number of microcontroller peripheral lines required to read the keyboard. A key is read by
strobing the columns and reading all rows for each strobed column. Key-down data is
interpreted by the display microcontroller and sent back to the main microprocessor using
proprietary encoding schemes.

Digital circuitry

for the following discussion on digital circuitry.

Microprocessor

U135 is a 68332 microprocessor that oversees all operating aspects of the instrument. The
MPU has a 16-bit data bus and provides a 21-bit address bus. It also has parallel and serial
ports for controlling various circuits. For example, the RXD and TXD lines are used for
the RS-232 interface.

The MPU clock frequency of 19.92MHz is controlled by crystal Y101. MPU RESET is
performed momentarily on power-up.

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Содержание 2750

Страница 1: ...Model 2750 Multimeter Switch System Service Manual 2015 Keithley Instruments All rights reserved Cleveland Ohio U S A Second Printing August 2015 Document Number 2750 902 01 Rev B...

Страница 2: ...into the manual Addenda are numbered sequentially When a new Revision is created all Addenda associated with the previous Revi sion of the manual are incorporated into the new Revision of the manual...

Страница 3: ...egory I and must not be directly connected to mains voltage or to voltage sources with high transient over voltages Installation Category II connections require protection for high transient over volt...

Страница 4: ...e 1000 volts or more including the com bined effect of normal and common mode voltages Use standard safety precautions to avoid personal contact with these voltages The WARNING heading in a manual exp...

Страница 5: ...rifying DC voltage 1 8 Verifying AC voltage 1 10 Verifying DC current 1 11 Verifying AC current 1 13 Verifying normal resistance 1 14 Verifying dry circuit resistance 1 16 Verifying temperature 1 18 V...

Страница 6: ...d test equipment 2 23 Extender board connections 2 24 Model 7700 calibration 2 24 3 Routine Maintenance Introduction 3 2 Setting the line voltage and replacing the line fuse 3 2 Replacing the AMPS fus...

Страница 7: ...emoval 5 4 Motherboard removal 5 4 Card cage removal 5 5 Front panel disassembly 5 5 Removing power components 5 5 Instrument reassembly 5 6 Input terminal wire connections 5 6 Power module wire conne...

Страница 8: ...alibration commands B 13 Manufacturing calibration commands B 15 Model 7700 calibration commands B 16 Remote error reporting B 21 Error summary B 21 Error queue B 24 Status byte EAV Error Available bi...

Страница 9: ...nections for Model 7700 AC current verification 1 25 Figure 1 13 Connections for Model 7700 resistance verification 1 to 10M ranges 1 27 Figure 1 14 Connections for Model 7700 resistance verification...

Страница 10: ...e 4 3 Analog circuitry block diagram 4 10 Figure 4 4 Simplified schematic of dry circuit ohms 4 13 5 Disassembly 6 Replaceable Parts A Accuracy and Optimization B Calibration Reference C Calibration P...

Страница 11: ...6 Model 7700 thermocouple temperature verification reading limits 1 32 Table 1 17 Plug in module four wire RTD temperature verification reading limits 1 33 2 Calibration Table 2 1 Recommended equipmen...

Страница 12: ...l multiplexing and gain 4 22 Table 4 17 2 signal multiplexing and gain 4 23 Table 4 18 4 signal multiplexing and gain 4 23 Table 4 19 4 dry circuit signal multiplexing and gain 4 23 Table 4 20 Switchi...

Страница 13: ...1 PerformanceVerification...

Страница 14: ...strument is still under warranty and its performance is outside specified limits contact your Keithley representative or the factory to determine the cor rect course of action If the unit is not under...

Страница 15: ...the Model 2750 to warm up for at least two hours before conducting the verifica tion procedures If the instrument has been subjected to temperature extremes those outside the ranges stated above allo...

Страница 16: ...pm 1 0V 82ppm 10V 82ppm 100V 90ppm 700V 85ppm 20mA 60ppm 100mA 70ppm 1A 110ppm 2 2A 94ppm 1A 690ppm 2 2A 682ppm 1 95ppm 10 17ppm 100 17ppm 1k 12ppm 10k 11ppm 100k 13ppm 1M 18ppm 10M 37ppm 100M 120ppm...

Страница 17: ...of 30ppm of reading 5ppm of range the calculated limits are Reading limits 10V 10V 30ppm 10V 5ppm Reading limits 10V 0 0003 0 00005 Reading limits 10V 0 00035V Reading limits 9 99965V to 10 00035V Ca...

Страница 18: ...ion test procedures Verification test summary Verification tests can be performed either through the Model 2750 front panel terminals or through plug in modules This section contains the following pro...

Страница 19: ...outlined above Make sure the equipment is properly warmed up and connected to the correct input terminals Also make sure that the INPUTS switch is in the correct position Do not use autoranging for a...

Страница 20: ...front panel terminals simultaneously with plug in modules all cable insulation voltage ratings must equal or exceed the maximum voltage applied to either the front panel terminals or the plug in modul...

Страница 21: ...listed in Table 1 2 For each voltage setting be sure that the reading is within stated limits Table 1 2 DCV reading limits Range Applied DC Voltage Reading Limits 1 year 18 C to 28 C 100mV 1V 10V 100V...

Страница 22: ...steps to verify AC voltage accuracy 1 Connect the Model 2750 HI and LO INPUT jacks to the AC voltage calibrator as shown in Figure 1 2 Be sure the INPUTS switch is in the FRONT position Figure 1 2 Co...

Страница 23: ...he Model 2750 AMPS and INPUT LO jacks to the calibrator as shown in Figure 1 3 Be sure the INPUTS switch is in the FRONT position 2 Select the DC current measurement function by pressing the DCI key T...

Страница 24: ...Reading Limits 1 year 18 C to 28 C 20mA 100mA 1A 3A 20 0000mA 100 0000mA 1 000000A 3 000000A 19 89960 to 20 01040mA 99 9100 to 100 0900mA 0 999160 to 1 000840A 2 99628 to 3 00372A Source positive and...

Страница 25: ...C current function by pressing the ACI key Figure 1 4 Connections for Model 2750 AC current verification 3 Set the Model 2750 for the 1A range 4 Source 1A and 3A 1kHz full scale AC currents as summari...

Страница 26: ...ng shielded Teflon insulated or equivalent cables in a 4 wire configuration connect the Model 2750 INPUT and SENSE jacks to the calibrator as shown in Figure 1 5 Be sure the INPUTS switch is in the FR...

Страница 27: ...10M ranges summa rized in Table 1 6 and verify that the readings are within calculated limits 7 Connect the Model 2750 INPUT and SENSE jacks to the calibrator as shown in Figure 1 6 8 Disable externa...

Страница 28: ...he INPUTS switch is in the FRONT position Table 1 6 Limits for normal resistance verification Range Nominal Resistance Nominal Reading Limits 1 year 18 C to 28 C Recalculated Limits 1 10 100 1k 10k 10...

Страница 29: ...Enable OCOMP offset compensated ohms by pressing SHIFT then OCOMP Use OCOMP for 1 10 100 and 1k range verification Enable line sync ON by pressing SHIFT then LSYNC NOTE Maximum reading rate for the 1...

Страница 30: ...LE is displayed then press ENTER The unit then dis plays the thermocouple type TYPE K d Select a type J temperature sensor then press ENTER The unit then displays the reference junction type JUNC SIM...

Страница 31: ...s set the unit for the following display TYPE PT385 f Press ENTER to complete the temperature configuration process 3 Select the temperature function by pressing the TEMP key 4 Set the decade resistan...

Страница 32: ...nd 1 0001kHz Figure 1 8 Connections for Model 2750 frequency verification Model 7700 verification Use these procedures to verify measurement accuracy through the Model 7700 20 Channel Multiplexer Card...

Страница 33: ...on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position 3 Select the DC volts function by pressing the DCV key and...

Страница 34: ...tage calibra tor as shown in Figure 1 10 Figure 1 10 Connections for Model 7700 AC volts verification Table 1 10 Plug in module DCV reading limits Range Applied DC Voltage Reading Limits 1 year 18 to...

Страница 35: ...and 50kHz AC voltages for each of the ranges summarized in Table 1 11 and make sure that the respective Model 2750 readings fall within stated limits 6 Press the OPEN key to open Channel 1 Table 1 11...

Страница 36: ...on 3 Select the DC current measurement function by pressing the DCI key 4 Set the Model 2750 for the 20mA range Close Channel 21 by pressing the CLOSE key then ENTER for SINGLE channel and keying in 1...

Страница 37: ...Set the Model 2750 for the 1A range Close Channel 21 by pressing the CLOSE key then ENTER for SINGLE channel and keying in 121 Figure 1 12 Connections for Model 7700 AC current verification Table 1 1...

Страница 38: ...e calibrator as shown in Figure 1 13 2 Install the Model 7700 in Slot 1 of the Model 2750 then turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel I...

Страница 39: ...00 resistance verification 100M range H L H L AMPS H L H L H L H L H L H L LO CH21 CH22 CH11 CH12 CH13 CH14 CH15 CH16 H L H L H L H L CH17 CH18 CH19 CH20 SENSE OHMS 4 WIRE INPUT V 2 WIRE H L H L H L H...

Страница 40: ...range 0 8 lead resistance Ensure that relay and cable connections have 0 8 of resistance before verifying the 1 range Table 1 14 Limits for plug in module normal resistance verification Range Nominal...

Страница 41: ...Close Channel 1 by pressing the CLOSE key then ENTER for SINGLE channel and keying in 101 5 Set the Model 2750 for the dry circuit resistance function by pressing SHIFT then DRYCKT Figure 1 15 Connec...

Страница 42: ...sistance values for the 1 1k ranges summarized in Table 1 15 and verify that the readings are within calculated limits Table 1 15 Limits for plug in module dry circuit resistance verification Range No...

Страница 43: ...utput terminals and ice point reference to the Model 7700 CH1 H and L INPUT terminals using low thermal shielded connec tions as shown in Figure 1 16 Figure 1 16 Connections for Model 7700 thermocoupl...

Страница 44: ...at TCOUPLE is displayed then press ENTER The unit displays the thermocouple type TYPE J d Select a type K temperature sensor then press ENTER The unit displays the reference junction type JUNC SIM e S...

Страница 45: ...its and RTD temperature sensor 0 00385 as follows a Press SHIFT then SENSOR and note the unit displays the temperature units UNITS C b Press ENTER and note the unit displays the sensor type SENS TCOUP...

Страница 46: ...function generator to output a 1kHz 1V RMS sine wave 4 Select the Model 2750 frequency function by pressing the FREQ key Close Chan nel 1 by pressing the CLOSE key then ENTER for SINGLE channel and k...

Страница 47: ...3 Select the Model 2750 DCV function and the 1V range Close Channel 1 by press ing the CLOSE key then ENTER for SINGLE channel and keying in 101 4 Select the Model 2750 RATIO function press SHIFT then...

Страница 48: ...1 36 Performance Verification Model 2750 Multimeter Switch System Service Manual...

Страница 49: ...2 Calibration...

Страница 50: ...bus or the RS 232 port DC only and AC only cali bration may be performed individually if desired Environmental conditions Conduct the calibration procedures in a location that has An ambient temperat...

Страница 51: ...tests Some of the procedures in this section may expose you to dangerous voltages Use standard safety precautions when such dangerous volt ages are encountered to avoid personal injury or death caused...

Страница 52: ...he factory default code is 002750 Use the left and right arrow keys to move among the digits use the up range key to increment numbers and press the down range key to specify alphabetic letters Confir...

Страница 53: ...and AC only calibration procedures You can use alternate equipment such as a DC transfer standard and characterized resistors as long as the equipment has specifications at least as good as those list...

Страница 54: ...pen calibration DC voltage calibration Resistance calibration DC current calibration AC voltage calibration AC current calibration Setting calibration dates Preparing the Model 2750 for calibration 1...

Страница 55: ...ep drafts away from low thermal connections to avoid thermal drift which could affect calibration accuracy 2 Press ENTER to start short circuit calibration While the unit is calibrating it will displa...

Страница 56: ...ter the front panel short and open procedure the unit will prompt you for the first DC voltage 10V Do the following 1 Connect the calibrator to the Model 2750 as shown in Figure 2 2 Wait three min ute...

Страница 57: ...ts and turn external sense off 3 Perform the steps listed in Table 2 3 to complete DC volts calibration For each calibration step Set the calibrator to the indicated value and make sure it is in OPERA...

Страница 58: ...ibration steps summarized in Table 2 4 For each step Set the calibrator to the indicated value and place the unit in operate If the calibrator cannot output the exact resistance value use the Model 27...

Страница 59: ...ent and make sure the unit is in OPERATE Make sure the Model 2750 display indicates the correct calibration current Press ENTER to complete each step Allow the Model 2750 to finish each step NOTE If y...

Страница 60: ...complete each step Wait until the Model 2750 completes each step Table 2 6 AC voltage calibration summary Calibration Step Calibrator Voltage Frequency 10mV AC at 1kHz 100mV AC at 1kHz 100mV AC at 50k...

Страница 61: ...l prompt you to enter the calibration date and the calibration due date Set these dates as follows 1 At the CAL DATE prompt use the left and right arrow keys and the range keys to set the calibration...

Страница 62: ...g calibration constants Locking out calibration NOTE As with front panel calibration you can choose to perform comprehensive DC only or AC only calibration Be sure to include a space character between...

Страница 63: ...rmal short and then send this command CAL PROT DC STEP2 NOTE Be sure to minimize movement near front input terminals Excessive movements can cause capacitive coupling errors which could affect calibra...

Страница 64: ...lue Send the indicated programming command Change the command parameter if you are using a different calibration resistance than that shown Wait until the Model 2750 completes each step before continu...

Страница 65: ...in operate Use the recommended current if possible Send the indicated programming command Change the current parameter if you are using a different calibration current Wait until the Model 2750 comple...

Страница 66: ...and Wait until the Model 2750 completes each step before continuing Table 2 11 AC voltage calibration programming steps Calibration Step Calibrator Voltage Frequency Calibration Command 10mV AC at 1kH...

Страница 67: ...on due date by sending the following commands CAL PROT DATE year month day CAL PROT NDUE year month day For example the following commands assume calibration dates of 3 5 2001 and 3 5 2002 respectivel...

Страница 68: ...g calibration steps In addition you will need the calibrator Table 2 1 and signal generator to com plete the comprehensive calibration steps Extender board preparation Before performing manufacturing...

Страница 69: ...the signal amplitude Front panel manufacturing calibration 1 Install the shorted calibration extender board see Extender board preparation earlier in this section in scanner card Slot 1 and select th...

Страница 70: ...then save calibration to complete the process Remote manufacturing calibration 1 Install the shorted calibration extender board see Extender board preparation earlier in this section in scanner card...

Страница 71: ...red previously 9 Set the generator to output a 1V RMS 1kHz sine wave then send the following command CAL PROT AC STEP15 1E3 10 Send the following commands to set calibration dates save calibration and...

Страница 72: ...l 2750 to warm up for at least two hours Front panel Model 7700 calibration 1 Connect the Model 7700 to the Model 7797 Calibration Extender Board see Extender board connections 2 With the power off in...

Страница 73: ...and record the cold temperature of the Model 7700 card sur face at the center of the card 4 Press in and hold the Model 2750 OPEN key while turning on the power 5 Enable calibration by sending the CO...

Страница 74: ...2 26 Calibration Model 2750 Multimeter Switch System Service Manual...

Страница 75: ...Routine Maintenance 3 RoutineMaintenance...

Страница 76: ...o the instrument front and rear before replacing the line fuse The power line fuse is located in the power module next to the AC power receptacle Figure 3 1 If the line voltage must be changed or if t...

Страница 77: ...n When the selector is installed into the fuse holder assembly the correct line voltage appears inverted in the window 4 Install the fuse holder assembly into the power module by pushing it in until i...

Страница 78: ...r current rating than specified or instrument damage may occur If the instrument repeatedly blows fuses locate and correct the cause of the trouble before replacing the fuse 3 Remove the fuse and repl...

Страница 79: ...odule amps fuses 1 Turn off the power and disconnect the power line and external connections from the Model 7700 2 Open the Model 7700 top cover 3 Locate the amps fuses for CH21 and CH22 Figure 3 3 4...

Страница 80: ...or several hours in a 50 C low humidity environment before use 9 Reinstall the circuit board into the plastic housing then close the top cover Replacing non volatile RAM battery The Model 2750 has a t...

Страница 81: ...Before replacing the battery refer to the troubleshooting procedures in Table 4 4 in Section 4 to determine if the battery requires replacement 2 Remove the Model 2750 top cover using the disassembly...

Страница 82: ...channels send this query via remote ROUTe CLOSe COUNt clist Here clist is the summary of channels For example to determine the closure count of channels 1 and 4 of a module in slot 1 the following qu...

Страница 83: ...mporary RAM every time a channel is closed regardless of how it was closed by an SCPI command front panel control or during a scan These counts are permanently written to the EEPROM on the card only a...

Страница 84: ...support brackets Rack mount procedure The Model 2750 can be mounted in a standard 19 inch rack For a mainframe that has one or no switching modules installed the Model 2750 can be secured to the fron...

Страница 85: ...e bottom of the Model 2750 The retaining screw for an assembly is located under the rubber foot Simply pull off the rubber feet to gain access to the screws Retain these foot assemblies for future use...

Страница 86: ...3 12 Routine Maintenance Model 2750 Multimeter Switch System Service Manual...

Страница 87: ...Troubleshooting 4 Troubleshooting...

Страница 88: ...ations Before making any repairs to the Model 2750 be sure to read the following considerations CAUTION The PC boards are built using surface mount techniques and require spe cialized equipment and sk...

Страница 89: ...that it is functioning properly When the key is released the message NO KEY PRESS is displayed 4 Pressing EXIT tests the EXIT key However the second consecutive press of EXIT aborts the test and retu...

Страница 90: ...ry block diagram Figure 4 3 Analog circuitry block diagram Power supply The following information provides some basic circuit theory that can be used as an aid to troubleshoot the power supply A block...

Страница 91: ...e for the display filaments is taken from a power transformer secondary at F1 and F2 and then routed to the display board Each DC supply uses a rectifier and a capacitive filter and many supplies use...

Страница 92: ...B Analog Circuitry See Figure 4 3 Display Board Controller U401 Display DS401 Trigger U146 Trigger Link TRIG IN TRIG OUT NVRAM U136 ROM U156 U157 RAM U151 U152 U164 U193 XTAL Y101 RS 232 U159 RS 232 P...

Страница 93: ...he drivers are serially transmitted from the microcontroller MOSI and PC1 Filament voltage for the display is derived from the power supply transformer F1 and F2 The display drivers require 37VDC and...

Страница 94: ...0 and U161 make up the IEEE 488 interface U158 a 9914A GPIA takes care of routine bus overhead such as handshaking while U160 and U161 provide the necessary buffering and drive capabilities Trigger ci...

Страница 95: ...Model 2750 Multimeter Switch System Service Manual Troubleshooting 4 9 Troubleshooting Analog circuitry Refer to Figure 4 3 for the following discussion on analog circuitry...

Страница 96: ...Q104 Q108 Q113 X1 Buffer U113 Digital Circuitry See Figure 4 2 ADC U165 A D MUX Gain U129 U132 U163 U166 SENSE HI ACV FREQ AMPS DCA ACA Slot Control Solid State Protection Front Terminals Scanner Outp...

Страница 97: ...the shunts For all other DCA ranges and all ACA ranges 0 1 R158 is shunted across the input K103 reset The ACA signal is then sent to the AC Switching Gain circuit while the DCA signal is routed direc...

Страница 98: ...lly to the INPUTS switch which selects between the front panel terminals and the scanner card outputs The Model 7700 7706 and 7708 modules contain CJC voltage temperature sensors These sensors are mul...

Страница 99: ...mplified schematic of dry circuit ohms SSP SSP SSP SSP DUT INPUT LO INPUT HI SENSE HI SENSE LO Mux SSP Solid State Protection Circuit ON I Source 10 A 100 A 1mA 10mA A D Converter Gain Amp 1M ON ON 0...

Страница 100: ...low briefly on power up then goes high 4MHz square wave Pulse train every 1msec Brief pulse train when front panel key is pressed Use front panel display test Digital 5V supply Display 37V supply Micr...

Страница 101: ...6 U135 pin 77 U135 pin 74 RAM OK ROM OK Digital common 5V 5VD supply 5V 5VB supply 3V Low on power up then goes high Check for stuck bits Check for stuck bits 32 758kHz Pulse train during RS 232 I O P...

Страница 102: ...multiplexer Table 4 5 DCV signal switching Range Q101 Q102 Q151 Q150 Q114 Q136 Q109 100mV 1V 10V 100V 1000V ON ON ON OFF OFF ON ON ON OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF ON ON...

Страница 103: ...SET RESET RESET RESET RESET RESET SET SET SET ON ON OFF OFF OFF ON ON OFF OFF OFF Range U105 Pin 9 U105 Pin 8 U103 Pin 16 U103 Pin 1 U105 Pin 1 U111 Pin 16 100mV 1V 10V 100V 750V OFF OFF ON ON ON OFF...

Страница 104: ...FF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF Range Q109 K101 K102 Q113 Q104 Q108 Q106 Q148 10 100 1k 10k 100k 1M 10M 100M OFF OFF OFF OFF OFF OFF ON ON SET SET SET SE...

Страница 105: ...N ON OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF Range Q109 K101 K102 Q113 Q104 Q108 Q106 Q148 1 10 100 1k 10k 100k 1M 10M 100M OFF OFF OFF OFF OFF OFF OFF ON ON SET SET SE...

Страница 106: ...F OFF ON ON ON ON OFF OFF OFF OFF K101 set states Pin 8 switched to Pin 7 Pin 3 switched to Pin 4 K102 reset states Pin 8 switched to Pin 9 Pin 3 switched to Pin 2 Table 4 10 2 4 reference signal swit...

Страница 107: ...ON ON OFF OFF ON ON SET SET SET SET ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON K104 set states Pin 8 switched to Pin 7 Pin 3 switched to Pin 4 Table 4 12 DCA signal switching Range K103 20mA 100...

Страница 108: ...at set up the gain for the final amplifier stage U166 Table 4 14 DCV signal multiplexing and gain Range Signal U163 U129 Pin 1 U129 Pin 8 U129 Pin 9 Gain U166 100mV 1V 10V 100V 1000V S4 S4 S4 S4 S4 OF...

Страница 109: ...al multiplexing and gain Range Signal U163 U129 Pin 1 U129 Pin 8 U129 Pin 9 Gain U166 1 10 100 1k 10k 100k 1M 10M 100M S4 then S7 S4 then S7 S4 then S7 S4 then S7 S4 then S7 S4 then S7 S4 then S7 S4 t...

Страница 110: ...ve the case cover as outlined in Section 5 3 Find the two firmware ROMs U156 and U157 located on the motherboard These are the only ICs installed in sockets Refer to the component layout drawing at th...

Страница 111: ...Disassembly 5 Disassembly...

Страница 112: ...utions when handling PC boards Wear cotton gloves Only handle PC boards by the edges and shields Do not touch any board traces or components not associated with repair Do not touch areas adjacent to e...

Страница 113: ...at a properly grounded work station Also ground yourself with a suitable wrist strap Handle the devices only by the body do not touch the pins Ground any printed circuit board into which a semiconduct...

Страница 114: ...the front rear switch rod 4 At the switch place the edge of a flat blade screwdriver in the notch on the push rod Gently twist the screwdriver while pulling the rod from the shaft 5 Unplug cables Unp...

Страница 115: ...ribbon cable from connector J1014 if you have not already done so 2 Remove the front panel assembly 3 Remove the four screws two on each side and two internal kep nuts that secure the front panel to t...

Страница 116: ...that all connections are properly made WARNING To ensure continued protection against electrical shock verify that power line ground green and yellow wire attached to the power module and the power tr...

Страница 117: ...assembly Power module wire connections Use the information in Table 5 2 and DETAIL B of drawing 2750 050 to connect power module wires Table 5 2 Power module wire colors Location Wire Color Top wire R...

Страница 118: ...5 8 Disassembly Model 2750 Multimeter Switch System Service Manual...

Страница 119: ...Replaceable Parts 6 ReplaceableParts...

Страница 120: ...o obtain information concerning replacement parts contact your Keithley representative or the factory see inside front cover for addresses When order ing parts be sure to include the following informa...

Страница 121: ...NPO C 514 01 C113 C114 C119 C126 C247 CAP 1000P 10 100V CERAMIC C 451 1000P C115 CAP 33UF 20 63V POLYCARBONATE C 482 33 C116 C118 C122 C124 C125 C127 C133 C135 CAP 1UF 20 50V CERAMIC C 418 1 C120 CAP...

Страница 122: ...C292 CAP 15P 1 100V CERAMIC C 512 15P C269 C271 C275 C276 C279 C298 C299 C149 CAP 1UF 20 50V CERAMIC C 418 1 C293 C294 CAP 47UF 20 25V ALUM ELEC C 314 47 C297 C302 CAP 1UF 20 50V CERAMIC C 418 1 C300...

Страница 123: ...L122 CHOKE 22UH CH 66 22 L121 CHOKE 100U SM INDUCTOR CH 66 100 LS101 BEEPER 5V 30MA QMX 05 EM 6 M315 M316 WIRE ROUTING CABLE CLAMP CC 88 1 Q101 Q102 Q159 N CHANNEL MOSFET TG 387 Q104 Q107 Q113 Q114 Q1...

Страница 124: ...R395 R352 RES 100K 1 100MW THICK FILM R 418 100K R123 RES 73 2K 1 100MW THICK FILM R 418 73 2K R124 R150 R211 R240 R258 R268 R271 RES 49 9K 1 100MW THICK FILM R 418 49 9K R125 R230 R232 R163 R305 RES...

Страница 125: ...R338 RES 10 5 1 8W METAL FILM R 246 10 R209 RES 332K 1 100MW THICK FILM R 418 332K R212 R217 RES 2 21K 1 100MW THICK FILM R 418 2 21K R215 RES 4 42K 1 1 4W METAL FILM R 391 4 42K R216 RES 2 87K 1 1 4...

Страница 126: ...FILM R 418 49 9K R297 R321 R322 RES 2 21K 1 100MW THICK FILM R 418 2 21K R302 RES 499 1 100MW THICK FILM R 418 499 R304 RES 20K 1 100MW THICK FILM R 418 20K R306 RES 4 99K 1 1 4W METAL FILM R 391 4 99...

Страница 127: ...T CS 553 TP103 TP104 TP106 TP107 SURFACE MOUNT PCB TEST POINT CS 1026 U101 IC VOLTAGE REG LM317M IC 846 U102 U118 IC J FET OP AMP TLE2081CD IC 967 U103 U105 U111 U129 IC CMOS ANALOG SWITCH DG211DY IC...

Страница 128: ...09 U149 IC NCHAN LAT DMOS QUADFET SD5400CY IC 893 U150 IC OPTOCOUPLER 2611 IC 690 U151 U152 U164 U193 IC 512K X 8 BIT CMOS SRAM LSI 234 70 U154 IC QUAD D FLIP FLOP W CLK RESET 74HC175 IC 923 U155 IC O...

Страница 129: ...Z5235BT1 DZ 100 VR105 VR106 DIODE ZENER 11V MMSZ11T1 DZ 103 VR107 VR108 DIODE ZENER 4 3V BZX84C4V3 DZ 85 VR109 DIODE ZENER 17V MMBZ5247BL DZ 104 VR110 VR111 DIODE ZENER 10V MMSZ5240B DZ 99 VR112 VR113...

Страница 130: ...ANGLE HEADER 16 PIN CS 1066 3 LED1 LED2 LED3 LED4 LED5 PILOT LIG HSMH T400 LED PL 92 1 LPI1 LPI2 LPI3 LPI4 LPI5 VERTICAL LIGHT PIPE PL 117 1 R401 R404 R406 R409 R411 R414 R418 RES 15k 1 100MW THICK F...

Страница 131: ...3 CONN RT ANGLE HEADER CS 1066 1 J4 CONN RT ANGLE HEADER 26 PIN CS 1066 2 J4 J5 CONN FEMALE 8 PIN CS 612 8 J5 CONN FEMALE 8 PIN CS 612 8 J6 CONN MALE 3 PIN CS 612 1 J6 J7 CONN MALE 3 PIN CS 612 1 L1 L...

Страница 132: ...CS 236 4 CONNECTOR CS 638 8 1 CONNECTOR HARDWARE KIT CS 713 4 CONNECTOR HOUSING CS 638 3 1 CONNECTOR MODULES CS 638 12 1 COVER 2750 309A 1 DISPLAY LENS 2750 307A 4 FOOT MOLDED 24322 4 FOOT RUBBER FE...

Страница 133: ...K25 K26 K27 SINGLE COIL LATCH RELAY RL 225 K22 K23 NON LATCHING RELAY RL 242 Q1 N CHANNEL P CHANNEL POWER MOSFET TG 360 Q2 Q4 TRANS PNP SILICON TG 388 Q3 Q6 Q49 Q50 TRANS NPN SILICON TG 389 Q34 36 38...

Страница 134: ...115 4 TE 121 CONN 6 PIN TE 115 6 U1 U2 U3 U4 U8 IC 8 STAGE SHIFT STORE MC14094BD IC 772 U11 U12 U13 U15 U17 U18 IC CENTIGRADE TEMP SENSOR LM35DM IC 906 U14 IC RETRIG MULTIVIB 74HC123AM IC 788 U16 IC...

Страница 135: ...Specifications A AccuracyandOptimization...

Страница 136: ...nge is 5V 200 V or from 4 9998V to 5 0002V DC current and resistance calculations are performed in exactly the same manner using the pertinent specifications ranges and input signal values Calculating...

Страница 137: ...the actual reading range is 13dBm 0 00032dBm dBm and dB for other voltage inputs can be calculated in exactly the same manner using pertinent specifications ranges and reference impedances Calculating...

Страница 138: ...g factor of 0 02ppm V must be added to DCV specifications for voltages over 500V Before calculating accuracy study the associated specifications very carefully to see if any derating factors apply Opt...

Страница 139: ...r has had factory setups restored DC voltage DC current and resistance Select 3 1 2 digits 0 01 PLC filter OFF fixed range AC voltage and AC current Select 3 1 2 digits 0 01 PLC filter OFF fixed range...

Страница 140: ...A 6 Accuracy and Optimization Model 2750 Multimeter Switch System Service Manual...

Страница 141: ...Calibration Reference B CalibrationReference...

Страница 142: ...bration lock except queries and CODE CODE up to 8 char string Calibration code or password default KI002750 COUNt Request the number of times the unit has been calibrated INITiate Initiate calibration...

Страница 143: ...z step STEP7 10V AC at 50kHz step STEP8 100V AC at 1kHz step STEP9 100V AC at 50kHz step STEP10 700V AC at 1kHz step STEP11 100mA AC at 1kHz step STEP12 1A AC at 1kHz step STEP13 2A AC at 1kHz step ST...

Страница 144: ...must be sent to the unit before sending any other comprehensive or manufacturing calibration command The default calibration code is KI002750 NOTE The CODE command should be sent only once before per...

Страница 145: ...be sent only once before performing either DC AC or factory calibration Do not send INIT before each calibration step Example CAL PROT INIT Initiate calibration LOCK CALibration PROTected LOCK Purpose...

Страница 146: ...PROT LOCK Request cal lock state SAVE CALibration PROTected SAVE Purpose To save calibration constants in EEROM after the calibration procedure Format cal prot save Parameters None Description The SA...

Страница 147: ...L menu NOTE The year month and day parameters must be delimited by commas Example CAL PROT DATE 2001 3 16 Send cal date 3 16 2001 CAL PROT DATE Request cal date NDUE CALibration PROTected NDUE Purpose...

Страница 148: ...ont panel input jacks before sending this command Example CAL PROT DC STEP1 Perform short circuit calibration Table B 2 DC calibration commands Command Description Parameter Limits CALibration PROTect...

Страница 149: ...ogram the 10V comprehensive calibration step Format cal prot dc step3 Cal_voltage Parameters Cal_voltage 9 to 11 V Description STEP3 programs the 10V DC comprehensive calibration step The allowable ra...

Страница 150: ...ration step Format cal prot dc step6 Cal_resistance Parameters Cal_resistance 90 to 110 Description STEP6 programs the 100 4 wire resistance comprehensive calibra tion step The allowable range of the...

Страница 151: ...omprehensive calibration step Format cal prot dc step9 Cal_resistance Parameters Cal_resistance 900E3 to 1 1E6 Description STEP9 programs the 1M comprehensive calibration step The allowable range of t...

Страница 152: ...on current parameter is from 90E 3 to 110E 3 Use the 100E 3 value whenever possible for best results Example CAL PROT DC STEP11 0 1 Program 100mA step STEP12 CALibration PROTected DC STEP12 Purpose To...

Страница 153: ...PROTected AC STEP1 10mV AC at 1kHz calibration step STEP2 100mV AC at 1kHz calibration step STEP3 100mV AC at 50kHz calibration step STEP4 1V AC at 1kHz calibration step STEP5 1V AC at 50kHz calibrat...

Страница 154: ...6 10V AC at 1kHz calibration step 7 10V AC at 50kHz calibration step 8 100V AC at 1kHz calibration step 9 100V AC at 50khz calibration step 10 700V AC at 1kHz calibration step 11 100mA AC at 1kHz cali...

Страница 155: ...15 Cal_frequency Parameters Cal_voltage 1 1V nominal Cal_frequency 1E3 1kHz nominal Description The AC STEP14 and AC STEP 15 commands program the two manufacturing AC calibration steps The appropriate...

Страница 156: ...Tected All commands in this subsystem are protected by the calibration lock except queries and CODE CODE up to 8 char string Send calibration code Default KI002750 CARD1 Path to calibrate card in slot...

Страница 157: ...he default calibration code is KI002750 NOTE The CODE command should be sent only once before performing calibration Do not send CODE before each calibration step The code parameter must be enclosed i...

Страница 158: ...ion PROTected CARD1 INITiate Purpose To initiate Model 7700 calibration procedures Format cal prot card1 init Parameters None Description The INIT command enables Model 7700 calibration when perform i...

Страница 159: ...bration PROTected CARD1 RCOunt Purpose To reset card calibration count to 0 Format cal prot card1 rco Parameters None Description The RCOunt command resets the card calibration count reported by COUNt...

Страница 160: ...le CAL PROT CARD1 SAVE Save card calibration constants STEP0 CALibration PROTected CARD1 STEP0 Purpose To perform Model 7700 calibration Format cal prot card1 step0 temp Parameters temp Cold calibrati...

Страница 161: ...mas All calibration errors will set Bit 3 in the Standard Event Register See the Model 2750 User s Manual Table B 5 Calibration errors Error Number Error Message 400 10 vdc zero error 401 100 vdc zero...

Страница 162: ...4 w zero error 427 1k 4 w zero error 428 10 2 w zero error 429 10k 4 w ocomp Ioff full scale error 430 10k 4 w ocomp Ion full scale error 438 Date of calibration not set 439 Next date of calibration...

Страница 163: ...nput time constant error 473 Frequency gain error 474 100 Ohm Ioff Ocomp FS error 475 10K Ohm Ioff Ocomp FS error 476 Temperature Cold Cal error 477 Analog output zero error 478 Analog output pos gain...

Страница 164: ...ll scale error 490 10 4 w dckt Ioff zero error 491 10 4 w dckt Ion zero error 492 10 4 w dckt full scale error 493 10 4 w full scale error 494 10 4 w ocomp Ion zero error 495 10 4 w ocomp Ion full sca...

Страница 165: ...status byte and error queue as outlined above to check for errors and to determine the exact nature of the error Detecting calibration step completion When sending remote calibration commands you must...

Страница 166: ...mmand must appear on the same line as the calibration command 4 After sending a calibration command repeatedly test the ESB Event Summary bit bit 5 in the status byte until it is set Use either the ST...

Страница 167: ...Calibration Program C CalibrationProgram...

Страница 168: ...nnecting cables Keithley Model 7007 Software requirements In order to use the calibration program you will need the following software Microsoft QBasic supplied with MS DOS 5 0 or later MS DOS version...

Страница 169: ...ault calibration code of KI002750 If the calibration code has been changed modify the CAL PROT CODE parameter accordingly 7 Run the program and follow the prompts on the screen to perform calibration...

Страница 170: ...nect calibrator to J and INPUT LO jacks GOSUB KeyCheck PRINT 1 OUTPUT 4 Msg PRINT 1 OUTPUT 4 OPER END SELECT IF I 2 THEN GOSUB Settle PRINT 1 OUTPUT 16 C Cmd OPC Send cal command to 2750 GOSUB CalEnd...

Страница 171: ...ay error RETURN Settle Calibrator settling routine DO PRINT 1 OUTPUT 4 ISR Query status register PRINT 1 ENTER 4 INPUT 2 s LOOP UNTIL s AND H1000 Test settle bit RETURN EndProg Close files end program...

Страница 172: ...V 1 KHZ AC STEP4 DATA OUT 1 V 50 KHZ AC STEP5 DATA OUT 10 V 1 KHZ AC STEP6 DATA OUT 10 V 50 KHZ AC STEP7 DATA OUT 100 V 1 KHZ AC STEP8 DATA OUT 100 V 50 KHZ AC STEP9 DATA OUT 700 V 1 KHZ AC STEP10 DAT...

Страница 173: ...agram 4 10 Analog signal switching states 4 16 Assembly drawings 5 3 B battery replacement 3 6 C Calibration 2 1 calibration aborting 2 6 AC current 2 13 AC voltage 2 12 code 2 4 comprehensive 2 5 con...

Страница 174: ...s B 8 DC characteristics accuracy A 2 DC current A 4 A 5 verifying Model 2700 1 11 verifying Model 7700 1 24 DC voltage A 4 A 5 Verifying Model 2700 1 8 verifying Model 7700 1 21 DCA signal multiplexi...

Страница 175: ...16 Module slot control 4 8 Motherboard removal 5 4 Multiplexer and A D converter 4 12 N No comm link error 4 24 O operation principles 4 4 Ordering information 6 2 P Parts lists 6 2 Performance Verif...

Страница 176: ...T Temperature A 4 A 5 temperature RTD Model 2700 1 19 RTD Model 7700 1 33 thermocouple Model 2700 1 18 thermocouple Model 7700 1 31 verifying Model 2700 1 18 verifying Model 7700 1 31 Trigger circuit...

Страница 177: ...to zero Unstable Overload Will not read applied input Calibration only Certificate of calibration required Data required attach any additional sheets as necessary Show a block diagram of your measure...

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