Dynamo charge :
To find out if the dynamo is charging:
Disconnect wires at D and F at dynamo and connect both terminals with short bit of wire. Connect Voltmeter with one end to a dynamoterminal, other end to chassis. Run engine. Voltage should go up steadily to 20 volt. If no reading: check brushgear. If reading is low, 1 volt then field is suspect. If reading is 5 volts then armaturewinding is faulty.
When the original VA voltage regulator and cut out gives the ghost you may as well fit the internals of an RB 106 inside the original VA casing. Its fits and does do its job very well. Its far cheaper and more reliable then overhauling the genuine machine.
Adjusting RB 106 regulator:
Place piece of cardboard in between cut out points (on the right)
Voltmeter in between D terminal and earth. Run engine untill voltmeter ticks back and stabilizes. This should be at 15.8 and 16.4 Volts bij 20deg C bij 10 deg C it is 16.1-16.7 V at 40degr C it is 15.3-15.9
Connect voltmeter in between D and earth and watch the cut out points move. Note the voltage before they close or when the needle slightly tickes back. Voltage should read 12.8-13.3 Volts.
Turn screws clockwise to raise settings.
Info from: The Automobile 12-99 and 1-2000, also MG TD Instruction Manual and Blower
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