Valhalla Scientific 4021 Operation Manual Download Page 1

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Operation Manual

Model 4021

Digital Ohmmeter

VA L H A L L A

Need Help? Call 800-548-9806.

www.valhallascientific.com

Summary of Contents for 4021

Page 1: ...Operation Manual Model 4021 Digital Ohmmeter VA L H A L L A S C I E N T I F I C Need Help Call 800 548 9806 www valhallascientific com 2015 Valhalla Scientific Inc All Rights Reserved...

Page 2: ...nty period for this instrument is stated on your invoice and packing list Please refer to these to determine appropriate warranty dates We will repair the instrument during the warranty period provide...

Page 3: ...or chassis ground terminal typically connects to the equipment s metal frame CAUTION Calls attention to a procedure practice or condition that could possibly cause damage to equipment or permanent los...

Page 4: ...T perform procedures involving cover or shield removal unless you are qualified to do so DO NOT operate damaged equipment Whenever it is possible that the safety protection features built into this pr...

Page 5: ...ce Measurements 15 Connections 16 Interpreting the Display 16 Chapter 6 Theory of Operation General 17 Troubleshooting 17 Circuit Descriptions 18 Power Supplies 18 Constant Current Source 19 Transcond...

Page 6: ...Chapter 4 Optional Equipment Chapter 4 contains information on all available options and test leads for the Valhalla Model 4021 Chapter 5 Operations Chapter 5 describes all operations including a desc...

Page 7: ...using an extension cord ensure the ground connection is continuous throughout the extension 2 For battery operated instruments use only the adapter provided or its exact equivalent The batteries may b...

Page 8: ...00 Hz This voltage range is preset at the factory and should be specified when placing the order All units are wired for 115VAC unless otherwise noted When 115VAC is selected the unit will operate at...

Page 9: ...locate the unit in the rack and make the power source and test lead connections The unit should be operated only in areas where the ambient temperature does not exceed 50 C If the internal temperature...

Page 10: ...5 of rng 2k 100m 1 9999k 100 A 0 05 of rdg 0 025 of rng 20k 1 19 999k 10 A 0 05 of rdg 0 025 of rng 200k 10 199 99k 1 A 0 07 of rdg 0 03 of rng 2M 100 1 9999M 100nA 0 1 of rdg 0 15 of rng Temperature...

Page 11: ...echargeable Ni Cad Batteries 1 2V 4000mA H Battery Charger Standard with DC Provides 6VDC at 300mA nominal Physical Specifications Width 9 5 24cm Depth 11 27cm Height 3 8cm Weight AC Power 3 lbs 1 5kg...

Page 12: ...provided if the 4021 has been fitted with Option HDB Additional adapters may be ordered as needed Option R4 Rack Mount Adapter Option R4 is an adapter tray that allows the Model 4021 to be installed i...

Page 13: ...in dual banana plugs at both ends Option KCS Kelvin Clips Option KCS is the gold plated Kelvin clips used on the Option K cable These clips may be used when making custom cables or when repairing Opti...

Page 14: ...itch The value of the range is indicated above the respective button Rear Panel Fuse holder The fuse holder is mounted on the rear panel and is designed to protect the internal circuitry For AC units...

Page 15: ...ance measurement of the load independent of the resistance of the current carrying leads Figure 1 Error Sources in Resistance Measurements Figure 1 illustrates how the 4 wire principle is used to elim...

Page 16: ...verrange condition This unpredictable display may make it seem to appear that the instrument is experiencing some sort of malfunction It is in fact just a characteristic of the voltmeter circuit and s...

Page 17: ...Troubleshooting Malfunctions are often the result of misinterpretation of specifications or due to an incomplete understanding of the instrument A thorough review of the operating instructions for th...

Page 18: ...er listed in the Parts Lists section at the back of this manual b Use only 63 37 grade rosin core electronic grade solder with a 50W or lower maximum power soldering iron c When soldering heat the ter...

Page 19: ...13 The heart of the constant current source is the voltage to current converter which incorporates a Transconductance Amplifier A simplified schematic of this unique circuit is shown in Figure 3 and d...

Page 20: ...ough RL increases the voltage at the input to IC4 A balanced condition will be reached when the output of IC4 is equal to the non inverting input of IC5 Again this condition occurs when the voltage dr...

Page 21: ...four 7 Segment LEDs DS2 DS5 and a 1 LED DS1 Concurrently driver transistors Q5 through Q9 are turned on in sequence This sequence is repeated at the 120 kHz rate and the data display consequently app...

Page 22: ...commended calibration interval is 1 year Required Test Equipment Following is a list of the standard resistors and other equipment required to calibrate the Model 4021 Precision Resistors 10 0 005 Acc...

Page 23: ...in specification 6 Disconnect the Voltage Calibrator Full Scale Adjustment 1 Select the 20k Range 2 Connect the Kelvin clips to a 10 standard resistor 3 Adjust R37 for a display reading of 0 010 4 Co...

Page 24: ...ry Batteries may be ordered from Valhalla Scientific as stock 05 10117 quantity 4 The process of battery replacement is described below 1 Remove the four feet screws and the bottom cover 2 Undo the re...

Page 25: ...ual Pin Number Data 1 1 2 2 3 4 4 8 6 10 7 20 8 40 9 80 11 100 12 200 13 400 14 800 16 1000 17 2000 18 4000 19 8000 21 10000 22 40 20000 overrange 26 5 VDC supply 50 0 VDC common 35 End of Conversion...