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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3457A Digital Multimeter
DIY voltage-current curve plot detector. Rear side of the LCD have metal shield, which is obviously not transparent. Experimentally, I figured out majual there is indeed balance offset.
This is good, even though not as impressive as HP A tweaking. Different non-modified HP A performance test, as received, 4-wire resistance function.
Changing The Security Code Much more important fact is, that display is now visible and usable at night time. Dc Volts Linearity Calibration LED supply power connections. Modifications log Thermal sensor and mounting manuxl Calibration coefficients are stored in SRAMwhich is powered even if instruments powered off, with help of on-board lithium battery.
Dc Current Offset Calibration After Q replacement with bp3457a curve than original and U more gain input amplifier circuitry started to oscillate with frequency around kHz. HP A overview Image 2: Resistance shunts for current measurement function.
There is no service manual schematics for this module in A documents, but such schematics available ho3457a A. Analog Devices ADA Instahation Of Options Base range, which is 3. There is possibility to save and recall multiple operation modes with all function settings, even after power cycle.
Overall block diagram Inguard isolated section has next circuits: Hope this can be helpful for other HP A owners. Diodes CR, CR ensure operation of the current mirror with their voltage drop. Ac Convertor a3 Assembly Removal This information is displayed on the screen and operator is expected to adjust R for best result.
Low ranges like 0. Input amplifier ready for testing.
All information posted here is hosted just for education purposes and provided AS IS. Self Test Description Input amplifier overview Image Turn the meter upside down, undo 6 screws if there are original rubber gaskets, there is no need to remove screws from cover.
As result there is no mechanical switch on front panel to change terminal side manually. Web-interface for access mirrored on this page.
This module even have same HP part number. Additional temperature sensor and output BNC port for it.
File:HP A operating – Hive13 Wiki
Dc Voltage Hp34577a Tests U hybrid design block diagram. HP A input amplifier after all modifications.
So I got idea to prevent running this ph3457a for intermediate testing. One kind person my kind regards presented me with thin copper foil with adhesive layer. Direct Mail Order System Dc Volts Offset Calibration Options And Accessories Now we can disconnect everything, assemble parts back and turn on for warming up and final tests, to make sure that meter reports still PASSED after a day or two.
I had no problems with self-test, as I had calibrated the balance during nanual repairs and troubleshooting in meter, before any modifications. After Q replacement the complete input amplifier balance had to be adjusted and re-calibrated.
Well, in analog design world things are much more complicated, and swapping components without understanding what the hpp3457a do is a road to a disaster and broken equipment. Offset Test Limits Wondering, if that is design issue of HP A, or simply particular unit trait.