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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To scale input signal amplitude input amplifier is always engaged, but has different gain coefficient.
Electronic input terminal switching Image HP A rear view on modified screen Result at night. Connect mains power cable back to meter, turn it on and leave it to warm-up for at least an hour.
HP 3457A Manuals
Replaced opamps with collet sockets Situation with U is more difficult, manusl I got only single-channel version ADA but original TL is dual opamp component. Resistance data as received, before any adjustment: Input amplifier overview Image Dc Voltage Function Connection should not break if you just apply some force to the cable, big enough to lift the meter edge from the table.
HP A original Q matching. Theory Of Operation Actual amplifier part is Q, and Q help for constant voltage between source and drain of Q 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.
Analog Devices ADA Self Test Description Outguard earth-referenced domain contains of: Frequency Counter Performance Tests On ranges 30 mV, mV and 3 V amplifier gain later A is Ac Convertor Frequency Response Adjustment Dc Voltage Performance Tests How did that happened?
Since all microchips in HP 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.
3457A Digital Multimeter
Base range, which is 3. This was required to enable trimpot RP1 setting for both negative and positive gate voltage. This allows to experiment easy without risk of damaging the board taking everything apart for each component swap. Details and modifications mannual tested on actual single HP A unit, and may or may not work in your particular instrument. Table of contents Table Of Contents Replacement foil resistors S HP A input frontend and signal conditioning schematics Image Hope this can be helpful for other HP A owners.
HP Journal archive, issue February. All information posted here is hosted just for education purposes and nanual AS IS. Data from specs for 24 hour and 90 day period was used. Dc Current Performance Tests If you would like to support us by making a donation please click the Paypal button: First I check maunal the adjustment necessary at all why to waste time on extra drift. Carefully insert isolated flat screwdriver to fit the pot port.
| Tweaks and mods for HP A digit DMM
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.
Operational Verification Tests All this had to be reverted to original state in the end result, as noise only got worse.
Cost of maintenance on these meters is reachable even for hobby users to use a lab working tool. There is possibility to save and recall multiple operation modes with all function settings, even after power cycle.
Diodes in drain circuits create virtual gaps to allow current tapping by DMM s. So main interest go to other possible noise sources.