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

["Henry" <apl2research(.a.t.)comcast.net>]

Hello General!

If you're just 'tossing' IIe Power Supplies away, can you open them up and 
cut the power connector off the PCB for me?  Send me an email and I'll give 
you my mailing address and a buck or Store credit for the postage.  I could 
use the cables.

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?

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.  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! ;-)

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!)

Sorry I couldn't be of more help.


-- 
Henry S. Courbis
www.GSE-Reactive.com
Apple II Series Legacy Hardware - Come take a look at what we have to offer!



"General_Failure" <tristan.mumford@gmail.com> wrote in message 
1148878241.849912.142640@i39g2000cwa.googlegroups.com">news:1148878241.849912.142640@i39g2000cwa.googlegroups.com...
>I would scrap at least 4 computer power supplies a year. Mostly from
> the instant-fuse-blow disorder. Just recently my apple //e's power
> supply has been added to that list.
>
> Initially I suspected the Z80 card, which I still believe may have
> started the problem. But now I don't know.
> Even with the power supply on its own, not plugged into anything, It
> has an instant fuse disintegration. Thankfully not as powerful as the
> lightshow a lot of x86 power supplies give.
>
> I can't see any problems with the PCB or components in the Dyna Comp
> power supply. Nothing is even remotely suspicious. It actually looks
> freshly built.
>
> Should I try tracing the fault, or just give up, steal it's low voltage
> cabling and give the apple a PC power supply?
>
> Also, after the first fuse blow, I decided to fit a panel mount fuse
> holder. Very convenient.
>
> With AT/ATX power supplies I never bother with trying to repair them.
> The apple supply is a bit of a rarity though.
>