Date   : Sun, 28 Aug 2005 09:45:11 +1200
From   : Michael Foot <mjfoot@...>
Subject: Re: Master 128 PSU ticking

In message <GMEPKGEKFAJNJOPABPFEOEFMCAAA.julesrichardsonuk@...>
          "Jules Richardson" <julesrichardsonuk@...> wrote:

> > >Hi,
> > >
> > >I have a M128 with a PSU that generates a ticking/pulsing sound when
> > >turned on. The sound appears to be coming from the middle of the PSU
> > >somewhere. The M128 does not power up.
> > >Has anyone experienced this before and is there a fix?
> >
> > Ticking is usually a sign of a short somewhere on the output
> > power rails..

[snip]

> A visual inspection's probably a good place to start after checking outputs
> on a meter - look for broken solder joints or obviously leaking capacitors
> etc.; then probably follow that with a check of any larger diodes on the
> output stages.

Fixed it. A visual inspection did find the problem. I did not realise there
are 2 fuses in the unit and it wasn't until I took it apart that I found
the fuse on the small riser card had blown. I replaced it and everything
worked again.

Since this M128 came to me with some others I have no idea about the history
of it but I could tell someone had previously been into the PSU. I don't
know what caused the fuse to blow in the first place, but all is well now.

Moving on, I have another M128 on which the CMOS setting are not being retained
even when the power is on. An 'R' reset does not reset the CMOS to the expected
values so it looks like the CMOS is failing to update.

Cheers,

Mike.

-- 
Michael Foot <mjfoot(at)paradise(dot)net(dot)nz> *
http://homepages.paradise.net.nz/mjfoot/
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