SF charging issue

S

Smartv11

Full member
Location
Meopham, Kent
Generator light is staying on...

Voltage across battery terminals is not rising, so looking to the generator bushes, but some of basic questions please;

1 - Polarise the generator - I read that I need to connect a jumper lead from DF to generator frame, therefore grounding the DF connection. To be doubly sure the generator frame is say the generator mounting bolt?

2 - the Bosch voltage regulator - this is rubber mounted, do I need to connect an earth cable from D- terminal on the voltage regulator to the frame? or is earthing at the generator terminal sufficient?

3 - Generator bushes - where can I get these from, I'm guessing they are Bosch parts?

Hopefully, one or more of the above should solve my Charging light?

Paul

Kent, Uk

 
Hi Paul,

1. No, with everything wired up correctly (see 2), connect battery plus to DF with a jumper cable for a short moment (not more than 3 sec.) to polarize the dynamo.

2. I have always thougt those dynamos have DF and  D+ terminals only, what do you mean by earthing D- to dynamo terminal? D- of the regulator (casing or connector) needs to be connected to ground (frame) anyway.

3. Bosch number of the brushes is 1107014144. Search the interwebs or ask for them at your local Bosch parts supply. Brushes are 6mm deep, 14mm wide and 19mm long when new.

All the best,
Stefan
 
Is there any current out of the dynamo?

If not, it's cooked.

If there is current, fault is either regulator or wiring, somewhere.

There is an earth terminal on the dynamo.

Paul
 
Gravelroad said:
Hi Paul,

1. No, with everything wired up correctly (see 2), connect battery plus to DF with a jumper cable for a short moment (not more than 3 sec.) to polarize the dynamo.
So, disconnect both cables off dynamo and jumper cable from battery+ to DF??

2. I have always thougt those dynamos have DF and  D+ terminals only, what do you mean by earthing D- to dynamo terminal? D- of the regulator (casing or connector) needs to be connected to ground (frame) anyway.
To be clear - i was referring to voltage regulator (under the petrol tank) - does these need an earth wire to frame?

3. Bosch number of the brushes is 1107014144. - thanks ordered a pair
Click to expand...

Paul
 
Smartv11 said:
Hi Paul,

1. No, with everything wired up correctly (see 2), connect battery plus to DF with a jumper cable for a short moment (not more than 3 sec.) to polarize the dynamo.
So, disconnect both cables off dynamo and jumper cable from battery+ to DF?? Yes

2. I have always thougt those dynamos have DF and  D+ terminals only, what do you mean by earthing D- to dynamo terminal? D- of the regulator (casing or connector) needs to be connected to ground (frame) anyway.
To be clear - i was referring to voltage regulator (under the petrol tank) - does these need an earth wire to frame? If the regulator case is mounted in rubbers, then yes.

3. Bosch number of the brushes is 1107014144. - thanks ordered a pair
Click to expand...
 
thanks,

The voltage regulator is rubber mounted to a newly powder coated frame... earthing very unlikely!

so a separate earth will be added :D

I hope this will be a simple cure to my generator light staying on

Paul
 
Brushes should be available from the
usual suspects, e.g. octeam.de
Or try to find them in the Volkswagen
beetle scene or (continental) vintage
tractor scene.
hth
Ernesto
 
And the easiest way to polarize a DC generator is to push the backfeed contact closed for a couple of seconds by finger. This of course when the generator is on the bike and the voltage regulator cover opened. And of course the belt off.
 
Thanks for all replies,

Tippee, your wiring diagram is great, Question, the D-  on the regulator looks like you suggest a cable back to the battery negative?

or is just an earth point on frame?

Being lazy now, as i'm not near the bike, but which terminal is D- ? is it the lower terminal below D+ ?

Paul
 
Isn't the "D-" the other end of the anchor winding that is grounded to the starter frame through the other brush that is not electrically isolated? I think it's made that way on most of direct current alternators. Then the D- is simply the ground, which has also a lot of other electrically connected to it, just marked as "D-" to make it clear the other brush is connected to it.
 
Yes it just goes to the frame for ground, and is part or the circuit so has to be a good connection. There are several ways to wire in DC generators it seems, Laverda one uses this system.
 
Thanks all for replies,

I've been working through the various tests for the charging system;

- Voltage across battery does not go up - so checked...
- Generator bushes are good as new
- Polarised the Generator
- checked continuity and earths

however, testing the Generator, with a jumper cable from DF to Generator frame and running engine from ground to D+ does not produce any voltage jump (to 35v or so).

So conclusion, I think the Generator needs repair / rebuild.

Any recommendation for this service in UK please?

Paul
 
It is easy to just open it up and check that everything looks ok inside. Remove it from the bike, take out the long screws and get the backplate with the brushes off, then remove the core with the drive side end plate. How does the surface that the brushes sit on look?, bearings not collapsed? etc. I was stranded once due to a wire between the field windings being broken, can?t remember how polarising test went but it was a simple fix.
You are in UK?, should be plenty of places that can service it if needs be, use uncle gogol.
 
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