[T3] OMG, My BRAIN died!
Keith Park
topnotch at nycap.rr.com
Sun Jul 7 16:35:35 PDT 2013
I see it! it does have the heat sink and the foam around the legs.
Yea, this should be fixable, I probably have a transistor here, although Im
more likely to have a rare, early, obsolete tube type than transistors...
Keith
Look in the opening at the end of the brain. Hold it flat, with the
PC board on the bottom. There's a TO-39 transistor inside, just past
the edge connector, on the right hand side. Sometimes they have a
heat sink snapped on them (probably a good idea.) This is the
transistor that provides the fuel pump relay ground.
Look at that transistor. Sometimes they are mounted off the board
with a plastic 3-pointed spacer and sometimes they have a little
spongy red rubber mat pad underneath them. If yours has the rubber
mat, it's possible that this has held moisture against the leads and
caused the leads to rust thru. (Yes, the leads are plated iron. You
can check with a magnet. You can tell if a lead has rusted thru by
trying to gently move the body of the transistor. If all three legs
are still intact it will be sturdy. If not, it will wiggle easily.
The transistor could also have lost an internal bond wire. That
sometimes happens to those old style metal cased transistors.
To provide a ground, I believe that would be an NPN. You can take the
cover off and replace it. You can probably get another 40 years out
of a similar TO-39, or move to something more modern. Pick anything
that can handle 20 V and 150% of whatever the relay draws. I just
grabbed something from my stash. I have more if you need one.
I've replaced exactly one of these. The hardest part was getting the
cover off and back on. You'll have to unscrew the board and hinge it
back on the ballast resistor leads to get at the underside of the
board, but that's easy.
--
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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