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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This is good, even though not as impressive as HP A tweaking. H P a Reed Relay Hope this can be helpful for other HP A owners.

HP 3457A Manuals

Even with shorted input, when reference noise irrelevant to ADC! It was the most troublesome, to pick and sort Q FET replacement. Frequency Counter Performance Tests HP A digital out-guard section.

Options And Accessories Suspects are listed below:. To my opinion, this was bit overdue addition, as previous model, A even with official specifications without any tweaks can be more precise and less noisy manuao A. Measurement noise data plots Few practical notes about modifications After Q janual the complete input amplifier balance had to be adjusted and re-calibrated. Hmm, hold on a moment? Input amplifier overview Image Shields locked in place.

Wondering, if that is design issue of HP A, or simply particular unit trait. HP Journal archive, issue February.


So I got idea to prevent running this procedure for intermediate testing. Resistance shunts for current measurement function.

Diodes CR, CR ensure operation of the current mirror with their voltage drop. All this had to be reverted to original state in the end result, as noise only got worse.

Basic DCV accuracy is specified better than 5 ppm. Line Voltage Selection Carefully lift rear side of the shield, disconnect cable from rear terminal and turn screen up.

It was common problem in other instrument HP Areading incorrect resistances when connections were loose. This is little tricky. All information posted here is hosted just for education purposes and provided AS IS.


Since all microchips in Manua A are in thru-hole type DIP style, all replaced components are carefully desoldered and positions on the board populated with high-quality collet-type sockets. Dc Voltage Function Replacement Q matching One kind person my kind regards presented me with thin copper foil with adhesive layer. Calibration coefficients are stored in Manuaowhich is powered even if instruments powered off, with help of on-board lithium hp3457w.

HP A original damaged R resistor. Different non-modified HP A performance test, as received, 4-wire resistance function. Ac Voltage Function Gain Test This module even have same HP part number. Inner protection shields Image 7: Replaced opamps with collet sockets Situation with U is more difficult, as I got only single-channel version ADA but original TL is dual opamp component.


LED mount for display backlight. Table below present measured data after calibration adjustment and performance verification. Experimentally, I figured out hp345a7 there is indeed balance offset. Capacitors used for stability compensation I used middle sweet spot device for replacement Q Note, that on low voltage ranges 0.

HP 3457A Operating Instructions Manual

Calibration and performance verification This section is added by xDevs. In service manual this procedure was explained for only case when self-test diagnistics related to this section unable to pass. Disconnect everything from the meter, including mains, GPIB and input cables.

Yes, it also does mean that calibration will be lost hp457a meter too old and battery discharged.

Cost of maintenance on these meters is reachable even for hobby users to use a lab working tool. HP A input frontend and signal conditioning schematics Image On alternating voltage, A is much weaker than older A. Operational Verification Tests Ac Convertor a3 Assembly Removal We sincerely promise to do better next time.

I tried to combine modifications in groups, so can hp347a multiple things at same h;3457a, when that was possible.