12 Apr
2010
12 Apr
'10
2:31 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of arcarlini at iee.org
Sent: 12 April 2010 22:06
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: VAXstation 4000 VLC Power Supply
Tony Duell [ard at p850ug1.demon.co.uk] wrote:
I swapped the PSUs of two VLCs and the fault followed the PSU, so I think
the chances of it being something connected to the PSU are quite low.
Nevertheless I will try removing stuff to see what happens, but there isn't
really that much to remove.
Thanks
Rob
A PSU that 'tweets' or clicks is starting up, detecting a problem and
shutting down to protect itself and the load. And then trying again.
Many moons ago I had a VS3100-76 more or less do this. I (eventually)
disconnected everything except the motherboard and PSU (no DIMMs,
nothing)
and amazingly it all worked. By this time I'd ripped everything apart
and
even removed the mainboard from the case.
A simple process of adding bits one at a time located the culprit:
the mouse.
This might be a reasonable starting point: have just the PSU and the
mainboard connected and nothing else (no monitor, no kbd, no mouse)
and see if the tweeting stops. If it does, you can now add bits one
a a time (kbd and monitor first, I think without a kbd it won't boot
properly).
Obviously if your PSU is now flakey or your mainboard is kaput then
you have more work ahead.
Antonio