Err, that transistor is there so that the rheostat doesn't double as a space
heater. It is there for a very good reason, although today there are better
ways to dim rather than a pass transistor. For that price, you could have
installed one of the pulse width modulated dimmers and done away with the old
fashioned piper circuit. Would have required a 337, but then it would be the
last time you'd ever have to deal with it. You might have even been able to
get separate dimmer circuits for instrument and overhead lights out of the
deal.

Jay Honeck wrote:

Get in there and do that kind of thing yourself and pay somebody to check
it
and sign it off !

Um, well, it took quite a while to determine that it was a problem with the
dimmer itself.

The circuitry for this thing is just totally bizarre. Rather than just
being a simple rheostat, it's hooked into some transistors, and capacitors,
and resistors -- all for no apparent reason. At first the shop thought it
was one of the transistors, but it blew instantly when they installed a new
one (at no charge to me), so they had to keep digging.

Mumble, grumble. Stupid 30 year old planes. I'm sure the new Cirrus panel
has everything in the dimmer circuit on a single chip, hidden somewhere in
the armrest, or something.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759