| Electronics > Repair |
| HP/Agilent 34401A - Error 745 |
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| ltktomas:
Hi a few days ago, when I was using one of my 34401A, it started to show error 745 since powering up. User Guide says that this error means: Cal checksum failed, FRES corrections. Interesting is If I let the instrument warm up, after about 5 minutes when I shut it down and then I switch it back on, the error disappears. But if I cool down the EEPROM chip (U505) on PCB, this error comes back. So I took soldering pen (maybe cold joints), but no changes. So do you think the EEPROM is faulty or (and I hope for this) it starts to "forget" ? Last calibration was performed in Dec 1999 and I think that this cool down/warm up thing only changes Vgs of a transistor inside the EEPROM that carries the CAL informations (so sometimes the information is 1 and sometimes is 0), so it could be repaired only by rewriting -> performing new calibration. What do you think ? |
| plesa:
Try to recalibrate and if it does not help order U505 from Keysight (U505 Keysight order code: 1818-5236 Description:IC 4K EEPROM 500-ns ). |
| voltsandjolts:
Discussed here: https://www.eevblog.com/forum/repair/agilent-34401a-selftest-ok-but-20-errors-(cal-checksum-failed)/ |
| Jwalling:
There's a document on Keysight that deals with this but I can't find it at the moment. This may help: http://www.azrefs.org/subject-a-guideline-to-fix-the-740-series-self-test-errors-for.html |
| ltktomas:
--- Quote from: voltsandjolts on August 21, 2016, 07:49:38 pm ---Discussed here: https://www.eevblog.com/forum/repair/agilent-34401a-selftest-ok-but-20-errors-(cal-checksum-failed)/ --- End quote --- Yes, I've already read this discussion. But the difference is that main says only Error 745 and only when it is not warmed up. I'll see what's going to happen after the calibration procedure. I just hope that the EEPROM chip started to forget after 17 years :-DMM |
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