Further damage report:
Today I swapped out the bad SISG4 board with the one I had ben keeping
for a small Twin project. All components were the same, so I just took out the
two terminal screws, broke loose the mounting silicone, and dropped the new
one in place. Easy!
When I examined the bad board from all sides, I realized another SIDAC
had bit the dust - the one on the "bottom" of the stack of three in that
section. It didn't look that bad until I poked it, and realized its tab was loose
as well. I shoulda figured one of the other SIDACs was dead - the heat from
the blasted-open middle SIDAC blistered the solder on the tabs of the two on
either side.
Although the IGBT looked fine, I put a ohmmeter across the section and
read a dead short. So I took the IGBT out, and sure enough the
collector-emitter resistance is very zero (with a DMM, leads in either direction).
Interestingly enough, the resistance from C-G and E-G is 10 ohms, again leads either
direction. And yet there's no visible external indication that there's
anything wrong with it. Anybody wanna buy a used IGBT, as-is? ;)
So far, the total is two SIDACs, the 24V TVS, and the IGBT all dead in
that section. And the coil still worked fine!
-Phil LaBudde
Center for the Advanced Study of Ballistic Improbabilities
**************Create a Home Theater Like the Pros. Watch the video on AOL
Home.
(http://home.aol.com/diy/home-improvement-eric-stromer?video=15?ncid=aolhom00030000000001)
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