RPM transducer repair

[Flieger]

I have found the part numbers for the item I need:

Porsche part number 901.615.111.00

Bosch part nr 0.333.400.01

[sithot]

See Post #6.

You would be driving the car by now. It's fun to fix things but sometimes it's better to use the sources that are available to us. Support these folks so they are around when you need them.

Good luck,

Tom

[mhackney]

Did you ask Otto if he has a repaired unit in stock? I know when I talked to him he did. The cost is higher of course, but you get the part asap without having to source one.

Cheers,
Michael

[Flieger]

I was looking for a core to send to Otto. Sorry I forgot to update this thread. Otto just got back to me with a quote for a complete unit and I will most likely need to go with this, despite the understandable cost.

The car ran without one, it just made a few rude "bangs" out of the exhaust occasionally.

I can drive the car still, so I am really glad.

[nickd]

Is it possible to source components for this board ? Now I'm not an electrical guy but the larger diameter silver component central to the board has 3 legs - two of which are broken - so I'm guessing the unit won't work too well when back on the car - so is this component available or is there a replacement component ??

I see -- BSX45 25 stamped on the side of the component.

Thanks ...

BTW this is a spare ....

[mikael]

I'm not an electrical guy either but a friend helped me with this. 5 components were changed (the ones with no nickel coating on the legs, the unprotected copper has just withered away).





The five components that usually need to be replaced:



The small transistors were changed from BCY58-1X to 2N2222A, the big transistor from BSX45-25 to BC140-16. D1 was changed to a 8.2V Zener (circled below). The Zener really should have been 8.4V but 8.2V is much easier to find and seems to work well.



It works great now, signal on at about 1500 rpm and off again when rpm drops to about 1300.

[nickd]

Mikael, thanks with the component numbers - very helpful. I guess it would be best to change out as advised ...

[sithot]

And now we know why time/technology marched on and left this contraption by the side of the road in favor or "reliability".

One of the coolest induction systems that was.

Glad you got it fixed!

[RSTarga]

I wish our current electronics lasted as long!!

[frederik]

I just repaired mine. Three of the small transistors needed replacing including D1. I just used BC549-C (a common NPN transistor in Europe) for all of them, and the RPM transducer worked fine after that. So it seems that there is no need to use a zener diode for D1. Maybe that will help others who need to do this repair.

I checked the correct RPM thresholds with the unit in the car. It also cycles the RPM correctly when you manually press the switch while the engine is at 2000 RPM, just like the CMA document describes. A short test drive confirmed everything is working well. I'm happy!