Faulty regulator?

[Johnny4428]

When I switch the ignition on I get a bit of heat in the black lead coming from the switch at the connecting block. So after a bit of fettling I discovered that when I disconnect the black lead from the voltage regulator that cures it. There appears to be open circuit from all three terminals to ground when tested this can’t be normal. Thoughts anybody? (Bike is not running when tested)

[cliff7]

As far as I know, with wires disconnected, all terminals on regulator should be open circuit to earth. Green wire should be connected to earth. Resistance between green and white wires (field coil) should be about 5 ohms. With wires disconnected resistance between black and green terminals on regulator should be about 35ish.

[Bryanj]

There will be a path from black to white on reg with ignition on which puts power to the generator field coil immediately key is turned

[Johnny4428]

Thanks guys couple of things there to check when I get my battery back or get a new one. Bought a new battery but think there is a duff cell in it put it back to local supplier who has it on charge for testing. I can do the resistance checks meantime.

[Johnny4428]

Tested resistance between green and white terminals 45.5ohm also between green and black 45.5ohm .

[Bryanj]

Never tested that but there is a hold in coil in there which would need a power and earth.
Connect the black and green up and measure votage at battery +ve, black at reg and white at reg all should be same.

[Johnny4428]

Ignition on for power, bike running or stopped?

[Bryanj]

Sorry tryping in work breaks, ignition switch on, lights and kill switch off so engine stopped and minimal electric load.
What you are looking for is "lost" volts caused by bad connectors or wires, black at reg should be less than half a volt below battery voltage

[Johnny4428]

Thanks Bryan, will try today.

[Johnny4428]

Results of test BryanJ, voltage between battery + and black on reg - 2.09 volts, battery + and white on reg - 2.60 volts. Quite a significant drop.

[Bryanj]

You need to find where the excess volt drop is.
Start at battery +ve and check at connections all way through

[Johnny4428]

Yes will do Bryan. I will keep you posted, Thanks.

[cliff7]

If it is getting warm at the ignition switch could it be bad connection onto switch (or faulty switch). Difference in voltage between black and white on regulator sounds like dirty points in regulator. Possibly. Didn't know they made a G3 in '61. I had one a while ago or was it an AJS.

[Johnny4428]

Thanks Cliff, yes a bit of checking to do tomorrow. Yes I have a post “jampot” model which was originally an MOD bike used by the aux fire team at an aerodrome in Scotland. When I restored it I painted it black.

[Johnny4428]

Sorry don’t know why that one was upside down.