Electronics > Metrology

HP 3458A ; A/D board spare part availibilty and cost

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voltampere:
Dear voltnuts,

i aquired a HP3458A fromm ebay in decent optical condition.
According to the date codes on the ic's it should be from 1989.
The A9 reference seems to be stable but i suspect the A3 PCB ( A/D board ) to be drifting seriously.
The drift is very random and unpredictable.
Sometimes it will not drift for about 12 hours. Sometimes it is running away 3 to 5 ppm in 12 hours.
It will always come back within 0,2 ppm after an ACAL DC.

I got in contact with Keysight Germany to get an idea how much a replacement A3 board would be.
First problem was finding the right part number. The part that is inside my unit seems to be the first edition.
The part number is 03458-66503. In the keysight part database you will get 03458-66513 as the replacement part number for it because the 66503 is obsolete now. But findapart@keysight.com emailed me that this part is"NFTS" meaning not for trade sale and that i should contact tech support at keysight germany for a repair of the HP3458.
I asked KS germany to quote for the 03458-66513 and the first reply was that they only have a few of these boards and they will not sell the spare parts but i can send the unit and they will replace the board. Material + labour = 2.000 € ( + VAT ).
I talked to some KS support guys on the phone and asked which part they would use to repair a new HP3458A ( RoHS version ).
They were unsure if that part would be compatible and said to contact me when they found out.
I read a post here where somebody confirmed that the new version of the A3 board ( part 03458-66523 ) would definitely work in older units ( fully backward compatible). So asked them if they would sell the 66523 spare to me.
Got an email two days later where they told me that they usually dont sell the new version either but would make an exemption and quoted 2.000€ ( + VAT ) for the board only!!!

That is just a bit too much i think.
Now my questions.

Does anybody have any experience about getting an A3 spare board ( tested, no second hand ).
Should i try to get it from another support center , UK for example?
Are the old version ( 66513 ) boards really that rare already?

I dont think i want to spend that much many for the spare board.
How are the chances to get my drifty boar cured?
I had the ( crazy ? ) idea to put the board in the oven at 60 degrees celsius for some hours to get the humidity out that might be the cause of the drift.
Would it cause more harm than help?

Hoping to get some ideas from the HP3458 repair experts...
( TIN ?!!! hello...  :D )

Thanks to all for any input on this

Best regards

joerg

TheSteve:
Your only choice is to buy a refurb board from Keysight as far as I know. They tend to have unknown drift/noise, some are certainly better then others.
If you can't find anything else and do really need one I have a refurb that has been tested for noise and drift I can sell.

Edwin G. Pettis:
Voltampere, your drift problem sounds suspiciously like a bad solder joint or cracked PCB trace, you might take a very close up look at your board and see if you can spot anything before popping for a replacement board.

TiN:
Graphs. This thread is pointless without graphs. I'd also wouldn't have any conclusion about ADC stability untill you ran the unit for a month, non-stop, to rule out storage/settling issues.

There are also more than two A3 versions, but even cheaper refub one would set you back $900+ USD if you are in US. Since you are in Germany, add extra and transform currency to EUR. So 1500 EUR+ is what I would expect as reasonable. :)

voltampere:
I did a quick inspection of the board. But will have a closer look again.

TiN ar you saying that i could still get a -66503 verision refurbished/tested from keysight?
Where ? At what price?

I did let the unit run for about 10 days and if i remember it right the situation got worse.
I want to do a longer run with logging. But before i do that i want to be sure that power supply incl. all relevant components are in good health. Dont want that ugly smoke coming out when i am not around...

I think that my board is the oldest version. Pictures attached.

Regards

Joerg

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