Modulator check

[Modbadger]

Apologies if this has come up before.... I'm trying to check with a multimeter that the input and output on a three pin OEM modulator are getting the correct voltage range in and out. I've got a Rayspeed type 12v loom, and lights and engine are running fine - this is not part of a build, the move to 12volts was made about ten years back, and has performed well.

On the regulator, from left to right, a yellow cable connnected to the flywheel, a brown cable to the round juction box, and an earth cable connected to a solid frame earth.

I have used the multimeter with the scoot engine running, black lead to earth, and the red lead, to first the yellow input to the modulator, and then to the brown output.

On the multimeter, first with its ACv set to 200, and then the DCv set to 20. All four checks gaving a quickly changing series of nmbers, the highest being 2.56. Revving the engine and turning the lights on made no difference to this. Can anyone has a better knowledge of Lammy electrics than I have let me know if this is a failure in the modulator? The purpose of the exercise is to check the modulator before I use another lead from the output to a voltage controller that will give me a 12v cigarette lighter socket.

[coaster]

What are your lights like? if they are ok but a bit dim on tick over but get brighter with revs then all is probably well. You should see between 12 and 14 volts with the engine spinning at about 3k rpm but will be a lot less than 12 volts on tick over. You will need the lights on otherwise most of the voltage will be dumped to earth by the regulator

[Modbadger]

Thanks for the advice, Coaster. I've (hopefully) solved the problem - it looks like my elderly modulator was at fault. Buying and fixing a new one (pjlscootshop on ebay, fast service) has provided the right voltage.