E3631A with error 501 and 625 - Page 1
Forum section: electronics / repair

author: Giovanni
author_rank: Newbie
timestamp: October 19, 2017, 08:01:21 pm
content: Hello everyone,As a long time reader (and buyer) I would like to ask for your help. The Agilent E3631A on my bench is still working but is sometimes beeping, sometimes with an error, sometimes not. Mostly it gives error 501 and only two times it gave error 625.501: Isolator UART Framing Error625: I/O Processor does not respondThe strange thing is that it just keeps working (kind of), only one time it set the output off during operation. But the beeping is annoying me and it tells me it isn't feeling that well.The service guide nor the internet (to what I can find) gives information about this errors. The isolators, which error 501 is talking about are used on three places, two at the 6V power supply, but they are analog, and one at the 'earth referenced logic' or GPIB/RS232 interfaces. That's the only one who could be generating that error, but I'm not using the interfaces (I'm aware it shouldn't make a difference, the communication between the processors is still alive, connected or not).Hmm, while I'm typing this message I feel I first have to check the isolator of the communication interfaces. Framing errors can also occur due to faulty isolators.But if anyone already faced this problem, please enlighten me.Best regards,Giovanni

author: HighVoltage
author_rank: Super Contributor
timestamp: October 19, 2017, 09:37:09 pm
content: I have not come across this problem but with many Agilent power supplies I have repaired, I can say:Always check all the voltage supply rails and the ripple voltage on them.Many errors are generated out of a bad power rail.

author: Samogon
author_rank: Frequent Contributor
timestamp: October 19, 2017, 09:46:54 pm
content: Especially floating logic power rail

author: Cerebus
author_rank: Super Contributor
timestamp: October 19, 2017, 10:02:22 pm
content: There are 2 optoisolators, U1 and U2 adjacent to the HPIB connector that provide Tx and Rx serial lines between the floating main CPU and the earth referenced CPU. Although you might not be using the HPIB, the main processor is still running a self-test that it can talk (via U1 and U2) to the earth referenced processor (U10) which also provides the RS232 port and the beeper.

author: Giovanni
author_rank: Newbie
timestamp: October 20, 2017, 10:03:09 am
content: Hello,Thank you for your replies.As it seems, the U1 and U2 opto's are fine. On both sides the signal looks solid and comply with the signal levels. Though on the rx side, the pulses are a bit rounded, seen at both the in and output, but in my opinion nothing to worry about. Also the data changed at tx when I adjusted the parameters on the front panel, just as expected.The supplies are ok too. The 5V floating logic supply is pretty noisy, but also not to really suspect, I've seen it alot with digital supplies. There is a acceptable ripple of 16mV according to my scope. Or is this too much for this system?I've noticed that during the measurements (probing) the beeps and error are occuring much less. Also during one measurement it gave error 625 three times at start up. But it did not occur again.Hmm..Best regards,Giovanni

author: Giovanni
author_rank: Newbie
timestamp: October 27, 2017, 09:09:46 am
content: Hello,Replaced U1 and U2 being the opto's between the main processor and the I/O processor (handles the RS232, beeper and GPIB). Unfortunately it did not help. I also tested without the opto's which resulted in no errors except for the 625 at startup (no communication possible). After that it was really quiet apart from a single beep in every while.Starting to suspect something in the I/O processor itself which seems a bit strange..Bought this supply for it's specs... (low noise / linear / tracking / etc.) What's a good replacement?GiovanniEdit: just after this message was posted a new error came up: Error -420 query unterminated. I do not use the gpib nor the RS232.

author: Samogon
author_rank: Frequent Contributor
timestamp: October 29, 2017, 02:36:59 am
content: Just for fun check if J3 connector is seated,no cold joints, dirt, broken cable etc. I had broken cable to the front panel and was tearing hear off, till i found that one connector was bad

author: bitseeker
author_rank: Super Contributor
timestamp: October 29, 2017, 05:50:17 am
content: With regard to connectors, sometimes simply plugging/unplugging them a few times will help as it scrapes off built up oxidation.

author: cecilroffey
author_rank: Newbie
timestamp: July 30, 2019, 10:47:36 am
content: Hi GiovanniDid you ever solve this problem of the beeping Err 625 as I have the same issue now...n beep at start up but all is working....I did have to replace U9 to get 25v rail working...it was down when i received the instrument.RegardsCecil