VAXstation 3100 power supply

[Peter Hicks]

Hi Dave

Superb, thanks - I hadn't thought about the rectifier diodes.

A word of caution for anyone replacing the 470uF/250V electrolytics near
the mains side of the board: the Nichicon like-for-like replacements are
shorter and wider than the ones they replace and don't actually fit.

Peter


On Mon, 8 Jun 2020 at 15:30, Dave Wade <dave.g4ugm at gmail.com> wrote:

> Peter,
> This is just generic advice based on recent experience. I would replace
> all electrolytic caps. I had some test pretty good, but PSU worked after I
> replaced them. Also check all the rectifier diodes as well, and I have had
> an opto-isolator fail.
> Dave
>
> > -----Original Message-----
> > From: cctech <cctech-bounces at classiccmp.org> On Behalf Of Peter Hicks
> via
> > cctech
> > Sent: 08 June 2020 15:10
> > To: cctech at classiccmp.org
> > Subject: VAXstation 3100 power supply
> >
> > Hello
> >
> > I have a couple of VAXstation 3100s - a M38 which boots but has no output
> > on the console port, and another model which has corrosion on the
> > motherboard and a PSU which doesn't power up correctly.
> >
> > The voltage on all of the M38 PSU's pins is OK except for pin 7 (brown)
> which
> > is +3.5v to +5.25v DC and is floating at about 0.6v with reference to
> ground.  I
> > suspect this is why the console port doesn't work (and the LEDs on the
> read
> > suggest a RAM problem so I can't tell which chip is faulty), so I've set
> about
> > troubleshooting.
> >
> > Does anyone have any suggestions above and beyond replacing capacitors?
> >
> >
> > Peter
> >
> > --
> >
> >
> > OpenTrainTimes Ltd. registered in England and Wales, company no.
> > 09504022.
> > Registered office: 13a Davenant Road, Upper Holloway, London N19
> > 3NW
> >
> >
> >
>
>
>

-- 


OpenTrainTimes Ltd. registered in England and Wales, company no. 
09504022.
Registered office: 13a Davenant Road, Upper Holloway, London N19 
3NW