On 10/18/21 4:31 PM, Don@True-Cal wrote:
Over many years, I have bought several non-working 3458A DMMs from several
sources, repaired/refurbish and resold them. Most needed a new A3 A/D
converter board 03458-66503 due to the well-known drift issue. I maintain
two such 3458As both on current Keysight service contracts with one on a
multi-year calibration contract that I have calibrated yearly and use to
keep my personal cal lab standards characterized.
Nice. Seems A3's U180 is the Achilles' heel of the 3458A. I think
my A3's failure is not related to the drift issue, though, specifically.
Has your A3 board actually failed or does it just have excessive drift? If
it has failed, what is the error code (maybe multiple codes)?
Here are the error codes that it throws, shortly after applying power:
209, "hardware failure - - timeout: unable to read A/D: 108"
114, system error - - multislope rundown convergence"
Last year, I removed my A3 board and sent it to a friend who is a
former design engineer at HP Loveland. He tested it in one of his
3458As. He said that the "board does work, but hangs the system after a
few samples are taken".
Running it with 10VDC input, it will run with an NPLC setting of 1 or
below, but produces the above errors pretty quickly with NPLC set higher.
I have always exchanged the failed 03458-66503 boards for a replacement
03458-66513 usually around $1300 exchange. Keysight now shows a 03458-66533
board as the replacement but offers no exchange and says instrument must be
returned for repair??? A search for HP 03458-66503 shows a company offering
a "tested" board for $899.
That's annoying; I wonder why the don't do the exchange deal anymore.
-Dave
--
Dave McGuire
McGuire Scientific Services, LLC
New Kensington, PA
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