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sick '70 power supply?
Date: Tue, 24 Mar 1992 17:22-0700
From: paul@PERSEPHONE.aegean-sea.dialnet.symbolics.com (Paul Cross)
I've got a 3670 that upon power up does not turn off its fault light. I
noticed that the main -12v light on the back back of the machine was not
lit, though all others were lit. I don't know if the bulb is burnt out
or if indeed there isn't -12v. On checking my powertec power supply,
model 6JA5-BBF-17, all the channels were normal except channel 3, which
was putting out 1v instead of its labeled voltage of 12. The
machine was fine this morning. I had to power it down to do a board
Sure sounds like a busted power supply to me.
What is the minimum board set one could put in an OBS machine and
have the fault light go out upon power up?
Just a guess: FEP and I/O. But it's possible that the FEP checks for the
existence of the processor boards.
Can I adjust the voltage of channel 3? Or, is there a fuse or breaker
that could have tripped? Or, do I need a replacement power supply?
There are adjustments on the power supplies, but they're not intended to
provide that much range (it would be appropriate if you were seeing 11.5).
I think you need to replace the power supply.