SteveB5815@aol.com wrote:
> My '79 MGB alternator is on the fritz. Can the
> internal components be bench tested with a digital volt/ohm meter to
> determine if they are working?
Troubleshoot as an US alternator.
1. Check voltage out with engine running and no electrical stuff on (should be
~13 -14 Volts at idle) Check at ~ 3000 rpm should be the same.
2. Turn on lights and check voltage at idle (again 13 -14) Check at 3000 rpm
3. Disconnect rectifier and check forward and reverse resistance of the diodes
(use resistance setting of voltmeter and check then reverse the leads and check
again). Should have zero resistance one direction and infinite the other.
4. If the voltages were high (overcharging) the regulator is probably shot. If
they were low remove the regulator and supply the hot side of the field (the
ungrounded brush) with battery voltage. Start car and check voltage it should
now be high (especially off idle) if it is the alternator is good and the
regulator is bad. If its still low and the rectifier checked out the alternator
is bad.
5. Check for noisy or high resistance bearings. If these are bad your better
off replacing the alternator (if it sthe rear one anyway since the bearing
passes
over the commutator).
On this topic has anyone replaced the lucas regulators with a domestic unit?
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