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Re: Does a ][ power supply ever take out its mobo?

sfahey wrote:

  To: jsnospam@cimmeri.com
  Re: Re: Does a ][ power supply ever take out its mobo?
  By: jsnospam@cimmeri.com to comp.sys.apple2 on Mon Jul 30 2007 08:09 am

 > << I've had two IIe PSUs die on me recently. Probably due to too much
 > strain because of too many cards installed... However, they do stink
 > differently when they blow up, too! ;-) bye Marcus>>
> > What were the actual failed components, Marcus? 

OK, the fried PSU and "stink" brought back a (to me) funny story. Years ago, I
was working as the jr. bench tech for an Apple Dealer ... it was my job to do
the initial diags, and fix the simple stuff or hand it off to the certified
guy. I mostly did swaps (most dealers did)...

One day, this very nice elderly lady came in with her ][+ complaining that it
was giving her error messages, and seemed hot. She also said it smelled weird,
like warm plastic and something else. But if she turned it off for awhile, it
would work fine for awhile until it got warm again.

I was thinking the PSU was the problem, and I was also going to offer to sell
her a system saver ... so I took the machine back to the bench and opened it
up. As I was making my inspection, I found several rolled and wadded up zip-loc
baggies under the keyboard, and stuffed around the power supply. It took all of
2 seconds to realize what was in them.

....and to figure out why the machine was running warm, and why it smelled
"funny" to her.

As it turned out, her grandson, who was living with her at the time was a
pretty active user and distributor - and the ][+ was his best hiding place.

When I found the problem, I didn't know what to do, so I talked to the senior
tech - and we explained to the lady what the problem was, gave the machine back
to her with the weed (removed from the case) and told her if the machine
continued to act wacky, sans the wacky tobaccy, to bring it back for a PSU
replacement.

But, I've found other interesting things in computers... dead mice, bugs a
plenty, forgotten tools and even money. Open enough computers and you'll see
some amazing things.


Sean, your story reminded me of something I found in a malfunctioning
radio (back when I was spending my Saturdays as a repair tech ;-).

The radio was making loud "staticy" noises and the volume was varying,
according to the repair ticket, so I thought I had another of the usual
"leaky printed mica capacitors in the input IF transformer" cases as I
turned it on on the bench to verify symptoms.

Sure enough, it sounded exactly like the AVC was malfunctioning due to
said leaky cap, so I took it out of its case to replace the IF
transformer (the cheap printed mica caps were inside the transformer
in the 1050s).

Lo and behold, out tumbled a wad of electrical tape with two wires that
had been clumsily spliced into the circuit!  When I unwrapped the tape,
I found a small VOM!

Apparently, someone had been probing the radio a year or so earlier, and
had noticed that the symptoms improved when the VOM probes were placed
between the AVC line and ground (shunting much of the leakage current to
ground), and had decided just to leave it there!  ;-)

I removed it (for placement in our "trophy case"), replaced the IF
transformer, and all was well.

Needless to say, this served to reinforce the contempt that the others
in the shop had for "do it yourselfers".

-michael

NadaNet file server for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."