[vcf-midatlantic] DECServer300 Internal PSU Wiring

David Hoelzer dhoelzer at enclaveforensics.com
Tue May 24 07:54:17 EDT 2016

I wrote a few weeks ago asking if anyone had any info on a Decserver 300.  This is a followup with useful info for future troubleshooters.

The issue was that the device was DOA. Probing with a meter revealed that there was no regulated output at 5, 12, or -12 on the low voltage side of the power supply.  With no obvious faults I recapped it to no avail.

Since there are absolutely no schematics to be had, I wasn’t interested in further troubleshooting the PSU board. I was able, however, to determine which pins were the -12 and ground and then, through deduction based on amp output of the board, which were the +12 and +5.  Hooking up a bench supply to the proper pins the Decserver works just fine.

Pinout for the ribbon cable from the PSU to the board is below. The board does not have any indicators for which pin is which number wise. For this reason I am numbering pin #1 as the pin closest to the edge of the board:

1, 2, 3, 4:		5 volts
5, 7:			ground
6:			key
8, 9:			+12 volts
10-14:		ground
15, 16:		-12 volts

Best regards

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