VAXmate PSU fixed, but no video

Rob Jarratt robert.jarratt at
Sat Apr 18 06:26:24 CDT 2020

Some of you may recall seeing me post about the VAXmate PSU failure. Thanks
to members of this list I found the failed part in the PSU and the PSU is
now working again. However, it looks like the PSU failed because of a
failure on the monitor board. There is a burning smell coming from it,
possibly the flyback transformer, but I am not 100% sure. I don't see
physical damage, but of course that doesn't mean there isn't a problem. When
I took the monitor board out again after this, I wasn't sure if the EHT lead
was making good contact with the CRT anode. The monitor board is described
in section 4.4 of this document:



I need some advice on diagnosing the problem, I have a few questions:


1.	If the EHT lead was not properly connected to the CRT anode, could
that cause problems?
2.	Is there anything I can safely do with a bench power supply to
isolate the problem?
3.	Any other suggestions for diagnosing the problem?
4.	There is an outline spec of the flyback transformer in the section of the VAXmate technical description, what chance of finding a
"modern" replacement?


I have posted about the PSU repair here:






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