Adjusting TR3 regulator

[Member 10617]

Can someone describe how to hook up a voltmeter to properly adjust a regulator?

 

[TR3driver]

The control box on a TR3 is a bit of a special case, at least if you want to follow the book method. The problem is that the box regulates both current and voltage, using a single relay. That means that the output current from the generator also affects the voltage setting. So the book method involves temporarily interrupting the current output, so the voltage can be checked with no current; and then setting the voltage to an unusually high value.

But the voltmeter connection is easy enough. If your car is still positive ground, connect the positive lead of the voltmeter to the 'E' terminal on the control box; and the negative lead to the 'D' terminal. If the car has been converted to negative ground, then the negative lead goes to 'E'. Actually, for most digital meters, it doesn't matter which lead is which, you'll just get a negative reading if it is connected backwards. But I still like to observe polarity, just because I grew up using analog meters that could be damaged by connecting them backwards.

The easy way (for me) to block the current during the setting process is to stick a bit of paper into the cutout relay contacts. I usually tear the paper into a kind of U shape, so it will hang in place and not fall out while I start the engine. The alternate method (given in the workshop manual) is to remove the wires from the A and A1 terminals, and temporarily join them together while disconnected from the control box (and the generator). Either one will work.