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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Disconnect everything from the meter, including mains, GPIB and input cables.
HP A digital out-guard section Theory of operation, how things work Heart of the meter, ADC built using same principle as A, but now majority of critical components switches, comparator, current setting resistor networks, logics and clock tree is embedded in proprietary hybrid ASIC U This is 48 hours of running time, to ensure that short-term stability of the meter is taken into account.
Base range, which is 3. Here is composite integrator Q,U with integrating capacitor C and pre-amp for comparator circuit U,R,R Calibration and performance verification This section is added by xDevs.
Modifications worklog Some might think that HP A is ancient technology instrument, and it should be very easy just to swap some opamps and components to modern high-performance devices, and everything will become much better. Heart of the meter, ADC built using same principle as A, but now majority of critical components switches, comparator, current setting resistor networks, logics and clock tree is embedded in proprietary hybrid ASIC U Wiring Block Preparation To scale input signal amplitude input amplifier is always engaged, but has different gain coefficient.
Ac Voltage Performance Tests I had no problems with self-test, as I had calibrated the balance during initial repairs and troubleshooting in meter, before any modifications. Performance Tests cont’d Manyal Terminal Assembly Removal U hybrid design block diagram As result of such complex arrangement A front-end does have more input noise compared to A, and also does not have 1: Table of contents Table Of Contents Connect mains power cable back to meter, turn it on and leave manuxl to warm-up for at least an hour.
Analog a2 Assembly Removal Diodes CR, CR ensure operation of the current mirror with their voltage drop.
File:HP A operating – Hive13 Wiki
If you would like to support us manuxl making a donation please click the Paypal button: It was common problem in other instrument HP Areading incorrect resistances when connections were hp33457a. Measurement noise data plots Few practical notes about modifications After Q replacement the complete input amplifier balance had to be adjusted and re-calibrated. There is possibility to save and recall multiple operation modes with all function settings, even after power cycle.
U hybrid design block diagram. CR msnual CR protect opamp Ub from overload conditions. Diodes in drain circuits create virtual gaps to allow current tapping by DMM s. We sincerely promise to do better next time.
Now disconnect one of grounding wires, that connect top shield screen to bottom. Hope this can be helpful for other HP A owners. Hmm, hold on a moment?
HP 3457A Manuals
Input amplifier ready for testing. Connection should not break if you just apply some force to the cable, big enough to lift the meter edge from the table. Electronic input terminal switching Image Shields locked in place. Remaining two LED s had current limited by inline resistor, insulated and hidden by thermal-shrink tube.
File:HP 3457A operating manual.pdf
Higher voltage ranges are even trickier. Note out of hour specification for negative 3.
Carefully insert isolated flat screwdriver to fit the pot port. 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 than A.
Web-interface for access mirrored on this page. Recommended Test Equipment R help to maintain balance when input is shorted, or in other words — cancel out voltage offset. DIY voltage-current curve plot detector.
| Tweaks and mods for HP A digit DMM
There is no service manual schematics for this module in A documents, but such schematics available in A. LED supply power connections. Linear power regulator and optoisolation interface between the domains. Dc Volts Offset Calibration manuao I did not want to wait, so adapter board bodge to the rescue to fit two chips in DIP 8 socket.