On an MGB, at least, disconnect all wiring from the F and D and connect the
two together. With a voltmeter connected between the bridged terminals and
ground, start the engine and slowly increase the rpms. The voltmeter should
show an increasing voltage, do NOT exceed 20 volts, this should happen
before 1000 rpm, do not race the engine in an attempt to increase the output
voltage.
If you get that the dyno is OK, you need to check the control box and
wiring. If only about 1v is output then the field winding may be faulty.
If you get about 4 or 5 volts then the armature winding may be faulty.
The control box effectively connects F and D together, and as the rpms
increase from idle and the output voltage increases to between 12.7v and
13.3v the
cut-in relay should operate, which connects the output of the dyno to the
battery. There are other things to check as well, but basically if you get
that then you should be charging.
PaulH.
http://freespace.virgin.net/paul.hunt1/
(or if that URL doesn't work try )
(http://194.168.54.52/paul.hunt1)
-----Original Message-----
From: Jhugheshtk@aol.com <Jhugheshtk@aol.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 12 September 1999 20:33
Subject: 1970 MG Midget
>I am trying to diagnose a generator problem:
>
>I am supposed to get 3 volts off the D terminal at 2000 rpm - I only get
1.5
>volts
>
>I am supposed to get 2 ohms when I check across the F term and + at the
bat.
> I peg the ohmmeter out!!
>
>Is my generator shot??
>
>Jeff Hughes
>Houston, TX
>
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