34970A ERR:625

[晓看风云]

I have been trying to repair a 34970A with error code 625, and I am certain that the AT89S52 chip is damaged, as the data read by the programmer differs each time. So, does anyone have the correct data? Could you send me a copy to help me resolve the 625 fault? I would be very grateful!

[Kleinstein]

Chances are the AT89S52 chip has the read out protection set. So the data are protected from reading and the programmer gets nonsense data instead.  So the defect may well be somewhere else.

[晓看风云]

Chances are the AT89S52 chip has the read out protection set. So the data are protected from reading and the programmer gets nonsense data instead.  So the defect may well be somewhere else.

Thank you very much for your suggestion！！Perhaps the AT89S52 does have a read protection function, but I can definitely confirm that it is damaged. As for whether the issue is program loss or something else, it remains unknown. Therefore, I'd like to try finding someone familiar with the 34970A chip to see if it has read protection to prevent access to its internal program. If not, could they provide a copy to help me repair it?

[voltsandjolts]

Just to be sure you could scope the RX/TX link to confirm the opto-iso is working as it should.
https://docs.keysight.com/kkbopen/what-is-the-meaning-of-error-625-when-performing-self-test-on-34970a-657251521.html

https://www.eevblog.com/forum/repair/agilent-34970a-gpib-controller-chip/msg1420243/#msg1420243

[TizianoHV]

I had the same error and it was the internal battery leaking acid and short-circuiting the pins of the opto insulator. Cleaning the PCB was enough.

[晓看风云]

Thank you for your suggestion. I have carefully read this topic before. But I have carefully checked all the hardware of my 34970A and finally confirmed that it is an issue with AT89S52.

[晓看风云]

Unfortunately, my instrument does not have the problem you encountered. When I got it, the battery was already out of power, so I suspect that prolonged power loss may have caused some unknown faults, which led to the damage of AT89S52.

[晓看风云]

The reason why  confirmed that AT89S52 has a malfunction is because I obtained a very old EE87C521 chip, which should be from HP 34970A. After installing it, the instrument no longer prompts ERR: 625, but there are other issues with the instrument and I am unable to read the data on 87C521. So I can only search for the data of AT89S52, I have all the conditions to read and write it.