morrisroad

Contemplating a rebuild of my CCU on my 92 C2 and am wondering how long does a typical rebuild last. Ottos from Venice appears to be the best choice from prior threads. I have heard of a rebuild lasting a few weeks to a year.

jimq

Why wouldnt a rebuild last as long as a new one? I wouldnt spend all that money if thats true. I would find a used one.

morrisroad

Quality of rebuild varies by rebuilder. You typically get a 30 day on a used one sometimes the warranty is better for a rebuilt.

darth

I don't understand why a repair wouldn't last longer than a year (i.e. if not indefinitely or close to it) unless there is something abnormal, like bad servos that take more current than what the circuitry is meant to supply. Beef up the output circuitry (i.e. transistors) is a good mod.

Bill

mojo747

One place gives a lifetime warranty. I was looking into this a while back. I think Mojorising here on Rennlist rebuilds them too.

springer3

I think there is a difference between getting your known part repaired by a reputable outfit, and purchasing a "rebuilt" unit with unknown history from the shady side.

Buy well, and the part is as good as a new one. Buy poorly, and expect trouble. Examples of poor history:

1) part from a car with over-voltage from failing alternator regulator, and everything is stressed (bad alternator happened to a Mercedes I owned, after I replaced all the burned-out bulbs, everything electronic in the car was flaky for years)

2) part is from car left at the sea coast or other harsh environment

3) part is recovered from fire or flood car

4) part was butchered by incompetent repair before "rebuilder" got it working (barely)

klr10

The most common failure on these units appears to be one (or more) of the driver chips for the servo motors. Before you change out or repair the CCU make sure none of the servo motors are jammed or shorted. I wouldn't recommend trying to 'beef up the output circuitry' as this could result in extreme overheating under these conditions. The chips in question would however benefit from the addition of heatsinks and maybe inline fuses to the servo motors to prevent future failures.

jimq

I fixed all my problems with the CCU by replacing both mixer servo motors.

darth

What I meant by beefing up the output circuitry is replacing the output drivers (i.e. if I remember correctly I replaced the blown originals due to a mechanically jammed servo with 2n3906 or 4's) with components which are a bit more robust/and not modifying it to put out more current or voltage than what is required in effect the same as heat sinking it but a bit more eligent. Once the outputs are compromized you've lost the buffering effect which can lead to extraneous currents and voltages back into the more complicated and delicate control circuitry. Which is more difficult to diagnose and repair. As far as the repair lasting I assummed it would be done correctly, I'm not sure how it can be done incorrectly and work to begin with.

morrisroad

Thanks everyone great info...any recommendations on the repair outfit. I see majorising and Ottos are two top choices.