This manual contains information relating to the installation, operation, performance testing, calibration, and service of the HP A Multimeter. The information. The HP A has seven functions with 3% to 6% digits of resolu- tion, extendable to 7% .. (). Opt Extra Operating and Service Manual. +$ Hp A Pdf User Manuals. View online or download Hp A Operating Instructions Manual, Service Manual.
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Optional Plug-in Assembly Removal HP A input amplifier after all bp3457a Image Now disconnect one of grounding wires, that connect top shield screen to bottom.
Now press 4 and ENT. Operational Verification Tests Calibration and performance verification This section hp345a7 added by xDevs. Also ambient temperature, humidity and pressure variations affect the stability and noise performance of the meter as well.
Final test data rainbow with all tested FET s: So in next chapter we will try some experiments for first four circuits. Final test data rainbow with all tested FET s:. First rule of repair — do not change or fix things, that are still working fine. LCD display removed from assembly. Also this unit has least weight in class, due to use of plastic instead of metal as covers material.
Resistance shunts for current measurement function – high-voltage divider 1: Resistance data as received, before any adjustment: This information is displayed on the screen and operator is expected to adjust R for best result. This section is added by xDevs. Wondering, if that is design issue of HP A, or simply particular unit trait. On alternating voltage, A is much weaker than older A. Closest to the base range is 3 V, which is not best case for sensitive measurements, such as 7V reference output.
Replacement foil resistors S After Q replacement with faster curve than original and U more gain input amplifier circuitry started to oscillate with frequency around kHz. DIY voltage-current curve plot detector. Special circuitry protects calibration data from unauthorized or random overwrite. Well, in analog design world things are much more complicated, and swapping components without understanding what the circuit do is a road to a disaster and broken equipment.
Note, that on low voltage ranges 0. Current-limiting resistors are mounted on additional board for the board with four LED s. We sincerely promise to do better next time. HP A input frontend and signal conditioning schematics. HP A original damaged R resistor. Worth to note, that this operational amplifier must be stable with both high and low gains, and as we will see later, most troublesome range for stability is 3 V.
File:HP 3457A operating manual.pdf
Preliminary Calibration Procedures When test jig controlled remotely by PC position of RP1 is manjal middle. U hybrid design block diagram. Key importance at this stage to probe output with oscilloscope, to ensure stable operation without any oscillation, with actual DC signal applied on the input, from zero all the way to the full scale 3 V. If you would like to support us by making a donation please click the Paypal button: Vos adjustment trimmer access port in shield cover.
I tried to combine modifications in groups, so can test multiple things at same amnual, when that was possible.
File:HP A operating – Hive13 Wiki
Shields locked in place. Instruments Covered By This Manual HP A internal calibration RAM battery check Special circuitry protects manal data from unauthorized or random overwrite. HP A rear view on modified screen.
Another time consuming challenge — complex approach type. Even with shorted input, when reference noise irrelevant to ADC! HP A rear view on modified screen Result at night. Don’t have an account?
This means that disassembly and cover removals not required for adjustment and calibration with few exceptions, covered later. Carefully insert isolated flat screwdriver to fit the pot port.