Re: When should a power supply be declared Perma-Dead?

["General_Failure" <tristan.mumford@gmail.com>]

>If you're just 'tossing' IIe Power Supplies away,

 Haha. Sorry, No. PC power supplies always die on me. They are
relatively cheap and plentiful.
This is my one and only //e power supply, with no scope of getting
another one.
I'm going to resurrect this one if I can. If not, the connector is
being put on to an AT power supply (or ATX if I'm in a fun mood). If
mini-ITX power supplies were more affordable, I'd put one of those in.

>I remember reading a little while back that sometimes one of the diodes in
>the Power Supply can cause the problem you're having.  Really, the only
>other way I know to blow the fuse if the system was just running fine would
>be to short one of the power lines to ground.  Anyone have any other ideas?

Exactly. Here's a tiny bit of background. The Z80 card was acting up,
so I pulled it and re-seated the ICs. After that the system would not
boot.
After a lot of stuffing around I discovered that one of the leads for
one of the caramic caps was touching the solder pad of the other. This
would create a short-circuit to earth, pinouts permitting. I'm pretty
sure those two caps are used for noise suppression on the Z80 soft
card.

>Maybe check under the Motherboard and make sure a screw or something of the
>like didn't work it's way under and start shorting things out.  I doubt a
>card could cause such a problem only because you can see both sides of the
>card.

Pardon. I'm afraid I don't follow what you are saying.

>  If something was wrong, you'd notice it right away just by looking.
>Most cards will actually fry a trace right off the board in a nice cloud of
>smoke before the power supply trips, unless it's a REALLY wide trace.  Don't
>ask how I know this! ;-)

That's for sure. Once I wasn't paying attention and plugged a Unix
terminal server into the nic on one of my PCs. Instantly vapourised a
track.

>We also sell a heavy-duty 200w Power Supply for the IIe if you'd like to
>give it a try.  It won't turn on if there's a short either. (shameless
>plug!)

If I could get one I would.

And also, like I said, even with no connection to the //e, the fuse
still instantly blows. There is no visible sign of damaged components
in the power supply either.