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(the months are 2015/2016)

The French Blatting Company

1949 MG TC




If you make up a small lead with tags on both ends, remove the wires from the dynamo and fit the link wire between the two terminals. Then using an analogue voltmeter (digital is OK but much easier to see the output on an analogue), clip the black lead to one end of the link wire, the red to a good earth. Start the engine and slowly increase the revs. You should see the voltage rise. Don’t let it go over 20v. Assuming you do see 20v the dynamo is working so test the wiring. Put the wires back (remove link). Start engine and clip the black lead to the D terminal on the regulator (5th from rear). Start engine, rev to 2000 rpn and ensure you still have an output. If you do then the regulator would seem to be faulty, if there is no output  it would appear the wire is broken. The wire from the D terminal on the dynamo and the D terminal on the regulator should be yellow. Also make sure the wires on the regulator haven’t come out the terminal. Just gently pull a wire at a time down (there are two) and ensure they’re both still screwed in.

To polarise a new dynamo, take a heavy wire from the negative battery lead and "flash" it to the F (small) terminal on the dynamo. Have the two wires off the dynamo whilst you do this. This will only ned to be done once.


(If you have changed your polartity to negative earth reverse the instruction from positive to negative.)