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Re: Apple /// & Vulcan IIgs Power Supplies went ka-boom



Toinet wrote:
On 8 nov, 22:32, "Michael J. Mahon" <mjma...@aol.com> wrote:
Toinet wrote:
On 8 nov, 04:46, "atfphotogra...@gmail.com" <atfphotogra...@gmail.com>
wrote:
Hello,
I'm also confused as to the settings on the caps? What does the
40/085/56 mean?
I'd like to help you but I can't.
I would to share two pictures:
  - my IIc dead capacitor:http://www.brutal-deluxe.fr/public/CAP_IIC_MONITOR.JPG
  - my IIe PSU:http://www.brutal-deluxe.fr/public/CAP_IIE_PSU.JPG
Remember the blinking LED on the motherboard! I was wondering whether
this could be due to the capacitor, they are all full of
"craquelures", oh! a French word.
Don't know about the blinking LED (very improbable), but these are both
examples of "X2" capacitors.  Replacing them as described earlier should
fix any problems related to them (except the residual odor ;-).

-michael

NadaNet 3.0 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

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

In response to "(very improbable)": http://www.brutal-deluxe.fr/public/APPLEIIE.AVI
A 6.8 MB video I did on 30/JUN/2009 with my digital camera.

I didn't mean that the blinking itself is improbable (though it is quite
unusual!), but that the failed line filter capacitor would not cause the
LED to blink.

I can't view your video as I'm writing this, since the computer must be
restarted to complete the Quicktime upgrade, but it sounds like a case
of the power supply being *just barely* overloaded, so that it goes into
shutdown after a short time, then attempts to restart and repeats this
cycle endlessly.

Most likely culprits are the electrolytic capacitors just after the
bridge rectifier--the only big electrolytics on the line side of the
supply.  When they age, they become less effective due to both a loss
of capacitance and an increase in equivalent series resistance.  This
erodes the supply's margin until it usually just stops working.  Yours
is a special case, where it is working for a short time, to blink the
LED, then shuts down.

-michael

NadaNet 3.0 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

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