3458A Repair - Page 1
Forum section: electronics / repair

author: Shiv
author_rank: Regular Contributor
timestamp: July 27, 2021, 12:46:45 pm
content: Hi all.I´m trying to repair 2 3458A (at least make one from both)N1: We was using this until failed-114 Multislope rundown convergence: suspected A3 board with no replacement.-209: Harware Failure: Timeout - Unable to read A/D: I don´t know from where I should start searching.N2: Was a mule, multiples failures, stored for more than 5 years:- It has no fan (replaced)- It has no reference (repaced)- RAM Test 1 Low (fixed with new dallas nvRAM, only 1230´s, I have no programmer yet)- Bad A3 board (don´t show any measurement) -> replaced by the other A3 and starts measuring, but fails after a whileActually has:- HARDWARE FAILURE FLATNESS DAC CONVERGENCE 198 -> Suspected failing A2U404 (+: 6.86V -:6.52V)-101: CALIBRATION ERROR (AutoCal fails at first step)PostScript: Changing A2 from first to second removes errors and start working, passes self test and autocal, but then, time passes:209: Harware Failure: Timeout - Unable to read A/D:229114: SYSTEM ERROR: Multislope Rundown convergence101:CALIBRATION ERRORWhen CAL 0 is executed, it shows:205: HARDWARE FAILURE CAL VALUE OUT OF RANGE:13Any clue?

author: coromonadalix
author_rank: Super Contributor
timestamp: July 27, 2021, 02:30:20 pm
content: you may get some hints on xdev's website, schematics too in some instances, may not be completeyou do know they are delicate equipments to work with, please do take antistatic precautionsa first step would be to check all psu sections / voltages and noise on the voltages if any, recap if needed.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 27, 2021, 03:53:46 pm
content: The multiple failures with unit 2 could very well be a supply problem. Otherwise the obvious way to test would be to use the A3 board from unit 2 in unit 1. The errors 114 and to a good chance also 209 are from the ADC board. The first fix / check there would be the comunication problem - best case it would be a loose fiber connector.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 27, 2021, 04:08:57 pm
content: Even saw a post of a fiber optic cable not inserted correctly, creating some error codes ...

author: bsdphk
author_rank: Regular Contributor
timestamp: July 27, 2021, 04:45:06 pm
content: The 3458A is quite sensitive to power-supply noise, so start with checking that all the psu rails are clean and in spec.

author: Shiv
author_rank: Regular Contributor
timestamp: July 28, 2021, 07:33:17 am
content: Quote from: coromonadalix on July 27, 2021, 02:30:20 pmThank you, I knew it.Xdevs have 3 or 4 3458A threads that are magic.PSUs are ok.I´m doing everything with gloves and antistatic wristband.Quote from: coromonadalix on July 27, 2021, 04:08:57 pmI checked it, seems to be fine. (I swapped fibers from one to other)I´m pretty sure I have both 3458A with bad A3 boards.One of them has:Dead A3 (multislope rundown convergence + no measurement)Damaged A2 (Flatness DAC convergence, waiting for A2U404)Other has:Damaged A3 (multislope rundown convergence when hot, keeps measuring)Any clue of what is "multislope convergence" related?

author: Kleinstein
author_rank: Super Contributor
timestamp: July 28, 2021, 09:13:52 am
content: The multi-slope convergence error comes up if the rundown part of the ADC no longer works properly.It is seen when U180 has drifted rather bad. It usually start with the ADC gain to drift, seen with a drift in the CAL72 values.There is a HP service not on this - mainly how to test if the ADC is about to fail and cause excessive drift.So one could probably test the still partially runing board for CAL72 drift.There may be other defects that could also cause the convergence error, e.g. a failure in the comparator. This also happes some time as they run quite hot. At least the comparator can be fixed - though not easy. Still chances are a comparator failure could also trigger another error message.With a broken comparator the run-up waveform would usually also not work.Other failures are possible of cause. So the hope is not totally lost. Still chances are the A3 baords are beyond repair (U180 bad) and would need an exchange at KS.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 28, 2021, 02:34:11 pm
content: I dont think KS has many A3 boards left ...

author: Kleinstein
author_rank: Super Contributor
timestamp: July 28, 2021, 03:33:05 pm
content: KS just redesigned the A3 baord for the new black edition and the new boards are supposed to be interchangable (may need a FW update if very old ?). However AFAIK the new A3 board is nomally (unless maybe for premium customers like NIST or NASA) no longer available for sale, but just as part of a repair at KS.So a broken A3 board is an expensive repair, but still possible. Sending the meter in is not that bad - one would likely need a new calibration (possibly with some low level extras) anyway. The extra cost for them to swap the board are likely not that high in comparison - hard to quantify with the bare board unoptanium.There may be an extra complication for private customers - but that is a different thread.

author: Shiv
author_rank: Regular Contributor
timestamp: July 29, 2021, 08:23:54 am
content: Quote from: Kleinstein on July 28, 2021, 03:33:05 pmWe aren´t as premium as NASA, but as premium as we can be in Spain: INTA, and they don´t sell (OFFICIALLY) spare A3 tu us, AFAIK they made an offer for upgrading it to new black ones (about 8k per unit)(UNOFFICIALLY: somebody said he´s searching for an old A3 laying somewere)We could just buy it, but i´m very reticent to solve everything with money and trash can.I´m sure there are easyly 50+ 3458A in the whole center. There are 12 only in my department, 2 broken.Any of that 50 may be broken and stored.I´m pretty sure there are useful ones stored somewere, so I don´t want to buy until I searched a bit.

author: michael_liu4444
author_rank: Contributor
timestamp: November 22, 2021, 07:30:56 am
content: Hello Everyone,I am looking for a A/D converter Board A3 (03458-66503) for my 3458A. ( or good chip 1NC1-0017 )Any you have a good one to sell to me ?Requirement: after install it to a 3458A, the 3458A should be able to pass self-test and Auto cal.Please send me a message to my email: michael_liu4444@163.comHope to hear from you soon.Thanks & regards,Liu Biao