[vcf-midatlantic] DECServer300 Internal PSU Wiring

Dave McGuire mcguire at neurotica.com
Tue May 24 09:11:56 EDT 2016

On 05/24/2016 07:54 AM, David Hoelzer via vcf-midatlantic wrote:
> 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

  Handy info, I've archived this.

  Since the -300 is a damn fine terminal server and there don't seem to
be many around, it might not be a bad idea to try to fix that power supply.


Dave McGuire, AK4HZ
New Kensington, PA

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