19 Dec
2015
19 Dec
'15
12:44 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Robert
Jarratt
Sent: 19 December 2015 19:19
To: 'General Discussion: On-Topic and Off-Topic Posts'
<cctalk at classiccmp.org>
Subject: RE: VAX 4000-500 PSU Overload?
current.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Dave
Wade
Sent: 19 December 2015 18:32
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: VAX 4000-500 PSU Overload?
Seeing as it already seems to have over current sensing, I guess it
has
some
> small resistors in there so perhaps it is possible to measure the I
detecting
notices one looks like this:-
http://uk.farnell.com/welwyn/oar1-r020fi/resistor-1-0r020/dp/1200359
Ah! So that is what those things are! I definitely think this one is something wrong and shutting down the 12V side. I have
just been doing
some tests with a dummy load and the 12V side will come up and then go
down a few moments later, sometimes it will stay up, it seems a bit
random.
I wonder if the voltage level detection thinks its out of spec, rather than
the over current parts. These PSUs afre exceedingly complex...
Presumably then, there is something wrong with the
overcurrent detection.
I will have to look into how you test these, or perhaps just replace them
and
see what happens.
I can't see the resistors themselves being the problem. Perhaps re-soldering
them
Regards
Rob
Dave
G4UGM