The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Joolstacho on 11.04. 2013 01:26

Title: Flash dynamo with JG 12v unit fitted?
Post by: Joolstacho on 11.04. 2013 01:26
I think I need to 'flash' my dynamo on the SR.
(I'm 'recommissioning the bike after many years non-use)
It has the JG 12v conversion unit fitted, and I'm wondering if I need to disconnect the JG before flashing the dynamo... does it make any difference? I guess that because the dynamo leads are disconnected for flashing that it shouldn't affect the JG unit, but just thought I'd better take the precaution of checking... don't want to risk cooking anything.
Title: Re: Flash dynamo with JG 12v unit fitted?
Post by: KeithJ on 11.04. 2013 08:18
I am not an electrical guru but I suggest very strongly do not flash the JG unit. In my experience flashing and electronics do not go together.  Probably best to check with Dave Lindsley who markets them http://www.davelindsley.co.uk/assets/pdf/Parts-Catalogue.pdf
Title: Re: Flash dynamo with JG 12v unit fitted?
Post by: KenF on 11.04. 2013 10:38
I think I'd disconnect the JG regulator before flashing the dynamo.

Also, remember that, for use with the JG, the field coil in your dynamo will have been connected between the dynamo output terminal (D) and the field coil input terminal (F), rather than with the conventional Lucas configuration. So, to flash it, you need to connect the field input terminal F to earth, and connect the dynamo output terminal (D) to the battery live. If you already knew that, apologies.

Cheers,

Ken
brightsparkmagnetos.com (http://brightsparkmagnetos.com)
Title: Re: Flash dynamo with JG 12v unit fitted?
Post by: Joolstacho on 11.04. 2013 11:03
Ken, many thanks. I'd forgotten that I'd altered the dynamo wiring (years ago!) for the JG unit, so as you say I need to 'flash' to the D terminal not the F. I'll try that in the morning. And I'll take the precaution of unplugging the JG before I do it. Otherwise I guess it's a dynamo out job.