Cruise Control Amp Transistors - PeachParts Mercedes-Benz Forum

automch · #1 09-11-2006, 02:32 PM

I am looking for the power transistor numbers for my 1983 300SD Cruise control Amplifier. It looks like a push-pull circuit with two transistors under a common heat sink. The Amplifier is a 002 545 16 32. There are no identifying numbers on the old burned transistors. Any help is greatly appreciated!

Rick76 · #2 09-11-2006, 05:06 PM

I don't have a module identical to yours to look at but usually modules of that vintage used BD437 and BD438 transistors. There are 2 of each. If these power transistors are burnt, you might also consider replacing the driver transistors as well (possibly BC337-25). Newark is very good at stocking original European transistors.

Also at a very minimum you should resolder all of the cube and rectangle shaped capacitors on the circuit board as the solder cracks around their leads. It makes it easier if you strip the conformal (lacquer) coating off the copper side of the board first. You can use gel paint remover - brush on with a china bristle brush. Allow to sit only till the coating krinkles and wash off with a water spray followed immediately with a thorough dry with compressed air.

automch · #3 09-11-2006, 09:34 PM

Thanks Rick,
I did a google search and found all the transistors. They look identical to the ones on the board so I am ordering them in the morning and will post an update after completing the repairs. Again thanks!