MicroVAX 3100 Model 95 Damaging SIMMs?

[Rob Jarratt]

> -----Original Message-----
> From: Rob Jarratt [mailto:robert.jarratt at ntlworld.com]
> Sent: 25 March 2011 23:22
> To: 'General Discussion: On-Topic and Off-Topic Posts'
> Subject: RE: MicroVAX 3100 Model 95 Damaging SIMMs?
> 
> > -----Original Message-----
> > From: cctalk-bounces at classiccmp.org [mailto:cctalk-
> > bounces at classiccmp.org] On Behalf Of Richard
> > Sent: 18 March 2011 02:56
> > To: cctalk
> > Subject: Re: MicroVAX 3100 Model 95 Damaging SIMMs?
> >
> >
> > In article <008301cbe4f8$36678f50$a336adf0$@ntlworld.com>,
> >     "Rob Jarratt" <robert.jarratt at ntlworld.com> writes:
> >
> > > No I have not, sounds like that is my next step, although I don't
> > > think I have the equipment to check if the PSU is operating to spec,
> > > I can visually check components.
> >
> > Supply voltages can be checked with a simple voltmeter.  With dummy
> > resistor loads on the PSU you can check current supplied by measuring
> > the voltage across the resistor load.
> > --
> > "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for
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> > />
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> 
> I have just been checking the outputs from the PSU and was wondering how
> "good" they are. Here is what I measured:
> 
> On the standard Molex connector the 5V output is around 5.3V, the 12V
> output is pretty much dead on. On the CPU power connector I measured
> these voltages:
> 
> 5.0V
> 5.3V
> 5.3V
> -12.46V
> -5.98V
> 5.31V
> 12.04V
> 5.31V
> 
> I am not sure what the nominal voltages are supposed to be on this
> connector (the -5.98 looks a bit suspicious) and how much out of tolerance
> they are. How do these voltages look?
> 
> Regards
> 
> Rob

Actually I just found some info on the PSU label, it says

V1  +5.1V
V2 +12.1V
V3 +3.3V
V4 -12 V
V5 -9V

Some of the voltages I measured are a long way from that. I certainly did
not measure 3.3V or anything close anywhere. Of course I am not sure which
of the pins I measured should be 3.3V and little clue which one it might be
except perhaps for the one that I measured at 5.0V which is only because it
is numerically closest. Should I be looking at replacing capacitors as
suggested, would that be the cause, or is it going to be something else
entirely? Having inspected the capacitors there is no *visual* sign of
anything wrong.

Thanks

Rob