Misc: Charging Systems Wiring Diagram for 1951 Rapide

[SteveO]

Hi all,
I did post a thread asking if anyone had a wiring diagram for a non standard Rapide. It looks as though quite a few people had a look, but presumably there isn't such am animal. However, rummaging through my files I have now found a wiring diagram I must have drawn myself while the bike was apart, so I offer it for comment. Can anyone see an error which might explain why the bike doesn't register a charge? I have now checked the drive in the primary case and all appears well. I know that the brake light and horn are wired through the ammeter, which they wouldn't be on a "normal" bike, but it looks as though the inspiration for the wiring was a late 60s or early 70s British bike with 12V electrics (Triumph? Norton Commando?), although it is clearly negative earth. There is an Alton alternator (two wire) and a Podtronics type regulator/rectifier. Can anyone suggest how an electrical dum-dum such as me with few tools apart from a cheap multimeter, can check the output from the alternator?

 

[timetraveller]

If I have understood your diagram then you have the output from the alternator regulator going directly to the battery, There is something, which might be a connector, in the red wire which goes to battery positive but if it is a connector it does not go to the ammeter but to the light switch and thence to the horn and brake light switch. It looks like you go through the horn to get to the dip switch!! I do not think that can be right. I have a suggestion but other more competent electrical pundits might have better ones and that is to forget a lot of what you have. You probably have a copy of Richardson's and that has the very simple wiring diagram used originally The use of an Alton plus regulator just replaces the output from the original dynamo so why not disconnect everything apart from the Alton.regulator and use your multimeter in the 10 amp setting and just start the bike and see if 10 amps is flowing. Make sure the battery is charged first and do not rev the engine or you will blow up the multimeter. Check if any current is flowing into the battery from the output from the regulator. If not then you could go upstream and see if there is anything coming out of the alternator itself. That will probably be AC and over 12 volts. Let usknow what you find.

 

[Jim Bush]

I did a full LED conversion with direction indicators, running lights, Alton generator & Grossert Starter. Due to using a modern handlebar switch with light guage wires, I had to introduce relays for lights & horn. I also introduced LED's in the back of the ammeter for engine/direction/high beam - they shine through the white plastic nicely. A year in use the system has proved to be reliable and very safe. Having the bright running lights is a plus to be noticed in traffic

 

[SteveO]

Thanks for the suggestions guys. I think I'm more inclined to go with Timetraveller's suggestion of reverting to the old set up. I'm struggling to understand why the PO wired it the way he did, as the only change was to alternator rather than dynamo. The electric foot of course would need an extra wire to the starter button, but that doesn't explain what I've got. I could of course buy a ready made harness from the VSC, which should go straight on...

 

[bmetcalf]

My harness is homemade and I put a connector like this at the rear of the UFM to make it easy to disconnect wires before lifting the UFM off the engine. The extra wire for the starter button would need to be addressed, though. The wires are connected with screw terminals under the rubber covers.

 

[SteveO]

Sorry for the long wait. I've had other issues to deal with. Firstly, a week or so ago, I took the Vincent along to the local club night. It was dark when I left, so I turned the lights on and got about 50 yards before the fuse blew and everything went out (not the engine fortunately, still on mag). It was too dark to ride home across country, so I left it at a mates and collected it the next day. I had modified the wiring in that I had separated the leads on my diagram, such that there was now a direct feed from the battery to the ammeter, as per the Vincent diagram and I had cut out the double connection, so the regulator/rectifier now fed the lighting switch as before. I not unnaturally assumed that was the problem, so today I took it out for a ride to check, new fuse and all the lights on. It ran perfectly happily for an hour! So that wasn't the problem. The ammeter showed a constant 2A discharge (LED front & rear). Now the motor was nice and warm and would tick over, I restarted the bike, put my multimeter into the regulator output set to 10A. No reading at all, so changed it to volts AC and put it into the two black wires out of the Alton. Once again, nothing. I presume from this that the alternator is sh**ged?

 

[Jim Bush]

I have always figured a blown fuse was the sign of an actual wiring fault that needs to be explored before bunging in a new one and continuing.
In checking the output from the Alton, I would disconnect it from the rest and try. The issue may be with downstream wiring, regulator etc.

 

[SteveO]

I have always figured a blown fuse was the sign of an actual wiring fault that needs to be explored before bunging in a new one and continuing.
In checking the output from the Alton, I would disconnect it from the rest and try. The issue may be with downstream wiring, regulator etc.

Jim, thanks for the interest. I actually tried the meter on the output from the Podtronics type regulator/rectifier first. Getting nothing from that, I tried it across the two leads direct from the alternator, set to the AC Volts scale. I expected to see something but it stayed at zero. What should I expect to see? Would the reading fluctuate? Am I doing something wrong? The alternator was disconnected from the rest of the electrical system as the two black leads go to yellow (input) into the Podtronics.

 

[Robert Watson]

It depends what iteration of an alton it is, there were about 4, with the 4th one being the one that survives the best. The earlier ones had issues with stripping gears and electronics failures.