old Bosch Alternator field connection

[catmandoo]

I have 2 alternators on my Mercedes OEM 636 diesel engine . The original one a Bosch 30 amp has an external engine sensed mechanical regulator but is disconnected . I want to bring it back into service as a spare with a new diode in the field circuit but can only identify the D+ and earth conections . Any one got any info on other connections and layout or where I can source a diagram ?

 

[William_H]

The connection to the field will be via brushes on to sli9p rings which are mounted usually on the end of the rotor away from the pulley. So usually if you can find the brushes you will find nearby the terminal to one of the brushes the other probably being connected to ground but also possibly connected to dio0des. So that may not be much help but may give you some clues if all else fails. goodluck Ollewill

 

[VicS]

I may be able to contribute a little as I have an old Volvo car which has an alternator with a separate regulator. Although my regulator is an electronic one earlier models had a mechanical regulator and my workshop manual covers both.

Both Bosch and SEV systems were fitted and extenally were similar and it seems that the individual bits were interchangeable as my car originally had a Bosch regulator and an SEV alternator.

My regulator has three colour coded wires comming from it: red, green and black (but I see from the manual that they could also be brown, black and white respectively) They are on a plug in connector at the regulator end.

The red (or brown) wire connects D+ on the regulator with 61 on the alternator and is the sensing/ field supply to the regulator.

The green (or white) wire connects DF to DF and is the field supply back to the alternator, going to the field coil (rotor) via one of the brushes (The other brush going to earth)

The back wire is the earth connetion between the two, D- to D- or possibly E.

The warning light must also be connected to 61/D+ but that appears to be internal with a separate terminal on the alternator.

It is sometime since I had it all adrift and it is difficult to see exactly what is what with a mirror and torch but it appears that the green and black wires go to the brush box (soldered connections) while the red wire goes to a separate spade connector.

I hope this may help you sort it all out.

Last time I had it all out was because one ot the wires had broken off at the alternator end so when you assemble yours make sure the wiring harness is clipped up securely at the alternator end.

I also replaced the brushes (minimum protruding brush length for the Bosch is 8mm) and I was able to get just the bare brushes from an auto electrician. Fitting them was a bit tricky though.

The workshop manual also has all the details for adjusting the mechanical regulator if you need to do that.

 

[catmandoo]

Yes I have green , red and black . When you mention workshop manual do you mean the Haynes one for a Volvo ?

 

[VicS]

Yes it's the Haynes manual for the 240 series up to about 1980. Later editions may not be quite so useful, perhaps but I dont really know.