Re: "Clicking" II+ power supply

["Matt J. McCullar" <mccullar@flash.net>]

"N.N. Thayer" <nnthayer@hotmail.com> wrote in message
1147656612.398919.134200@j73g2000cwa.googlegroups.com">news:1147656612.398919.134200@j73g2000cwa.googlegroups.com...
> I have an Apple II+ whose power supply is a little finicky. Sometimes,
> when I turn it on, it causes the speaker to emit a fast clicking noise,
> about two clicks per second, and the screen flashes in sync with the
> clicks.  If I turn it off, let it sit for a few moments, and then back
> on, everything works fine.  Other times, when I turn it on, it'll start
> up normally but I'll hear a moderately loud *pop* from right beneath
> the power switch.  This in particular scares me.
>
> I've never been inside one of these power supplies but it basically
> sounds to me like this one's ready to go at any time.  Should I be
> worried about any damage to my II+ that I cannot as yet see?  Could I
> perhaps extend the life of the power supply by not using the power
> switch directly, but instead employing one of those System Saver fans?

I repaired a few hundred of those power supplies back in the early '90s.  I
think what's happening is that the electrolytic capacitors inside your power
supply are starting to get weak.  They can be easily replaced by a qualified
technician; if you don't know what you're doing, though, you can  receive a
nasty shock.  These are not expensive parts, fortunately.

There is nothing particularly unusual about the outputs -- +5 volts, +12
volts, -5 volts.  Any old power supply will do the same thing, though of
course it may not necessarily fit inside your Apple.  But do a web search
(eBay?) and see who may have one.  Considering how old these things are,
however, you might end up buying a used one that may fail the week after you
get it.

It may not be easy to open, either.  Apple used rivets to hold one run of
power supplies together; later runs used screws.

As for the "pop" you're hearing, I think that's caused by arcing inside the
power switch itself.  I ran into that many times.  The switch can be easily
replaced, too.

I don't think your power supply will damage your Apple.  Either it works or
it doesn't.

Matt J. McCullar
Arlington, TX