In a message dated 98-10-28 16:13:18 EST, you write:
> I'm having some problems with the charging system on my TR3 and
> after reading the manual I'd like to see if someone can verify
> one of the tests it says to perform. The manual says to disconnect
> the wires from the generator, connect a short piece of wire between
> the two connectors on the generator, start the car and measure the
> voltage between these connectors. For some reason I'm a bit concerned
> about jumpering the connectors together. Seems like a short to me
> me. Has anyone tried this?
Drew,
Not to worry, it'll work just fine. One of the two terminals is the input to
the field windings, and the other is the charging output from the armature
windings. Normally, the field windings get current/voltage from the regulator,
something less than 15 volts. By varying the field current/voltage, the output
voltage is regulated to 14-15 volts. What this test does is shunt the output
of the generator directly to the field, bypassing the regulator. One of the
cautions the manual lists, or at least should list, is to limit the engine rpm
to a value low enough that the voltage you are measuring stays below 20 volts.
Since there is no longer a regulator in the circuit, the only limit on voltage
is the capability of the generator itself, which increases with rpm.
Operating near 20 volts for a long period of time would probably not be too
good for the generator, but for the time it takes to do the test, it is no
problem. When I first read of this test, I had the same thoughts as you, but
after analyzing the circuit, I understood how it would be alright. Several
folks on this list have done this test with no ill effects.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/index.html
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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