Bosch charging system 1972 750 SF

Paul LeClair

Paul LeClair

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Location
Calgary, Alberta, Canada
Hi all

not my bike, but I have done a lot of work on it for the owner over the years, fitted a WITT ignition, rewired the bike, general maintenance, etc. It is a 1972 Laverda 750 drum brake. HAs a Bosch charging system.

It is not charging. Zero output from the regulator, measured with a multi meter. Has a whopping 10 volts AC coming in to the regulator at 3,500 rpm from the generator. Going to replace the brushes in the generator again "while I am at it", was done several years ago. The Bosch regulator was replaced several years ago, although that actually turned out to be a grounding issue related to a rebuild on to a then freshly powder coated frame, and the grounding issue was resolved.

Is there a solid state regulator replacement available, if so what is it and where can it be purchased?

Any other thoughts or suggestions? A couple of photos of what I am working with. See below. The wiring you see, with heat shrink, is modern high quality wire and is my work from several years ago. I also checked for proper grounds, and for continuity in the various wires, all fine.

Paul LeClair

 

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Yes. I got one from OCT for the 750 I restored. Looked externally identical to original analogue one.

 
Test the generator with these simple steps which should let you know it it is gen or reg.
http://www.netlink.net/mp/volks/htm/gen.htm
The dc gennie gets fed current to build on by the regulator, so they can?t really be tested properly in isolation as I understand it.
My gennies have uncountable miles on the original brushes. The vibrating contact regs were not so reliable. I have the Sachse electronic reg now, and one of the multi colour diode battery monitor things as well as the genny lamp.
 
recently sent 3 x 5A Sachse regulators back to Marco as not one of them worked, waiting on an update

 
installed one on my 750 sf gen light would not go out till over 4000rpm
confused also about the #61 connection on the bosch b+ and 61 are on
the same terminal and it works no need to say the bosch is on the bike.
 
Don't forget to polarize the regulator when you have a generator equipped bike. Any time you disconnect/connect the battery. Typically it will stay polarize but if you accidentally short it. it could lose polarity. For sure polarize a new regulator.
 
henrywillms said:
Don't forget to polarize the regulator when you have a generator equipped bike. Any time you disconnect/connect the battery. Typically it will stay polarize but if you accidentally short it. it could lose polarity. For sure polarize a new regulator.
Click to expand...

Hi Henry, and all

polarize a regulator? Going to have to google that, sounds like something needing doing on an old Harley with a magneto.

hadn't even thought that the bike might have a generator, stupid me, will now have to check whether alternator or generator.

Paul LeClair
 
Hi Paul - if you read Tippie's link, it explains everything - including polarising the dynamo !  Would have thought that unlikely to be the problem.

The solid state Bosch 'plug and play' replacement regulator was identified by Piet some time ago - part no F026T02200.  A quick Google or look on fleabay identifies sources. 

There are cheaper alternatives, but quality may be an issue.  Here's one well engineered (UK) source that uses MOSFET switching http://www.dynamoregulators.com/dvr4.php  The 11 amp option matches original spec and safeguards the dynamo from being cooked with higher demands.
 
Paul....I learned the hard way on my SFC 750 when I replaced my regulator. I guess I touched a wrench between a  "+" connection and the frame at some point working on the bike. I replaced the regulator and did not polarize, not knowing at the time this was needed. It didn't charge. I went back to the auto electric shop I bought it at, and the old Italian auto electrician, Angelo, looked at me with some disdain and told me to polarize it. As I recall but please confirm, it was a jump wire from B+ to D+ on the regulator terminals. I am no electrical specialist but this worked and every time I replaced a battery I always polarized just to make sure. 
 
http://www.ebay.com/itm/371154617011?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

or wolfgang has originals for $160 USD

polarize is easy so first step
 
rpm-bert said:
hi , anybody tried or any experience of these  reg units  ? ,http://www.dynamoregulators.com/dvr4.php . ????
Click to expand...

Yes, fitted one and didn't work... took off the cap and one wire had already fallen off! :(

Cheap shit imho.

piet
 
well done Piet
I do like it when a well known and very clever bloke does not mess with the words!
I've not seen you do that before, but Toddy does it all the time. You two would be great company, if together at the same time.
CLEM
 
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