At 12:24 PM 6/9/04 +0000, bosoxfan00@comcast.net wrote:
>.... my voltage regulator ('57 - 1500) is clicking on and off. You can
>hear the noise while driving, and its noticeable in the fuel gauge needle
>moving back and forth abouth 1/4 inch each time the regulator clicks.
The control box "regulator relay" is supposed to vibrate rapidly while the
engine is running. It should not be clicking on/off at a slow rate. That
is more likely a malfunction involving the "cut-out relay". For some
entertaining and educational notes on how generators and regulators work,
check here:
http://chicagolandmgclub.com/techtips/585.html
>.... Not sure how to test the charging circuit with a voltmeter. Is it in
>the shop manual ?
Yes, there are instructions in the shop manual for testing the generator
and for adjusting the regulator.
Test the generator function first, independent of the control box. If the
generator can't put out a charging current the regulator has no chance of
helping..
When you know that the generator is working, then you can adjust the
control box to control the generator output.
The most common problem with the control box is drift in the setting giving
low output of the generator. A minor adjustment of the regulator relay can
fix that.
Second most common problem with the control box is having the regulator
relay fail in the closed contact condition. This causes the generator to
overcharge and self destruct by way of internal melt down. Any time you
repair of replace a failed generator, always check the function of the
control box to be sure it is not forcing abnormally high outpot at high
engine speed. If the regulator relay is stuck in the closed contact
condition and causing overcharging, replace the control box immediately
before you burn out another generator.
A less common problem with the control box is having the regulator relay
fail in the contact open condition. This has the same effect of worn out
brushes in the generator, no charging. Adjustment of the cut-out relay may
fix this (or maybe not if either relay has a failed coil).
If the "IGN" lamp on the dash cycles on and off with the slow clicking of
the control box, this indicates that the cut-out relay is cycling. This
should not happen (obviously). Adjustment of the cut-out relay may fix
it. Or, the control box itself may be functioning okay, and the problem
may be external, such as a wire shorted to ground.
The generator and regulator interconnect wiring is not very conplex when
viewed aside from other circuits. See here:
http://mgaguru.com/mgtech/electric/circ_c.htm
To test individual wires, disconnect both ends of a wire and use a test
light or ohm meter to check for continuity and for isolation from ground.
The cut-out relay is supposed to disconnect the generator from the battery
with low voltage condition where the generator might sink current and
discharge the battery. This could happen with abnormally low idle speed
when the generator has little or no output. It can also happen if the
generator is failing (usually worn brushes) and losing output at normal
speed. It may also happen if the battery is very nearly completely
discharged and at a low voltage state, or dead to the point of not being
able to take a charge or carry much current.
Hope this helps,
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
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