Subject: Repair of Dead IIgs DynaComp internal power supply!
Path: lobby!newstf02.news.aol.com!portc04.blue.aol.com!newsfeed.mathworks.com!logbridge.uoregon.edu!newshub.tc.umn.edu!lynx.unm.edu!capella.unm.edu!buggie
From: buggie@capella.unm.edu (stephen e buggie)
Newsgroups: comp.sys.apple2
Date: 26 Jul 1999 19:29:45 GMT
Organization: University of New Mexico, Albuquerque
Lines: 40
Message-ID: <7nicv9$bq6$1@lynx.unm.edu>
NNTP-Posting-Host: capella.unm.edu
X-Newsreader: TIN [version 1.2 PL2]








I've been transplanting working IIe power supplies into the IIgs internal
casing,m  with good results.  14 have been made so far, and they are
called "BUGG-POWER IIGS JR."

Yesterday I succeeded in repairing a dead Dynacomp power supply.  In fact,
I have replicated the repair in four units!

There are three patterns of failure in the IIgs DynaComp power supply:

(1) Fuse blows every time -- components look okay.

(2) Fuse is okay, but no voltage on any line.  Components look okay.

(3) Volts test okay with no load, but unit quits when attached to
motherboard.  Heat scorch marks on power supply circuit board.

This fix applies ONLY to #3, above.   It applies only to "early" Dynacomp
power supplies.  When inspecting the unit inside, the early versions have
one or fewer tall yellow thin capacitors at the bow-end (10v, 1000 ufd).
(The later versions have the five tall yellows).

To fix the unit, replace two tiny radial electrolytic capacitors:

REPLACE THESE:  1 ufd, 35v

NEW CAPACITORS:  1 ufd, 50v

	The new ones are slightly larger than the old.  Note the polarity:
The "-" terminal faces the stern (back) of the power supply.

I salvaged the 1 ufd, 50v capacitors from other units that died for other
reasons.   But they are available from Jameco for $0.04 in quantities of
100.

Steve Buggie	buggie@unm.edu		Gallup NM