At 05:09 PM 4/1/06, William Killeffer wrote:
>....
>I've been told to check the voltage on the terminals that lead into
>the temp gauge. With the switch on but the engine off, it's getting
>a constant 11-12 volts. It's supposed to fluctuate between that and
>0, but I don't know how much time there is between each fluctuation.
>This is supposed to be a sign of either a bad voltage regulator or a
>misconnected wire.
The device is called "voltage stabilizer" which is a bit of a
misnomer. It operates similar to te a turn signal flasher unit with
a square wave output switching between full system voltage and
off. The on/off cycle time is about 80/20, give or take a little,
depending on input system voltage, so as to have a relatively
constant "average" output of about around 10 volts.
The voltage stabilizer must have three electrical connections to
function. It has system voltage input and regulated output, and it
must also be grounded. In metal body cars like the MGs it can be
screwed to the body for grounding. If you are trying to bench test
it you will need a sepatate ground return wire connected to the mounting tab.
There is also a rumor that the device has a prefered mounting
position, and you may find an arrow and/or the word "top" or "up"
embossed on the case. I have not seen this myself, so I'm not sure
if it's real or not.
>Now, where is the voltage regulator?
I believe it was originally screwd to the bulkhead near the larger
instruments. I have also heard it may have been attached to the back
of the speedometer mounting or instrument panel on some MGB (perhaps
the later models).
>The books say it's up under the dash. I looked up there and saw
>something near the top of the underside of the dash that had four
>terminals on it,
This may be two pairs of spade terminls, each one being a common
double terminal secured with a rivet. It still needs to have the
case grounded as well.
>.... and what would it look like?
You can check the Moss Motors web site for part number 131-540 or
131-550. It is a very small image in a larger drawing. The printed
catalog has a better view of this part.
>.... I'm starting to think that this is one of those DPO problems
>that are hard to solve at best.
>....
Have pitty on the DPO, for they know not what they do (or did).
Barney Gaylord
1958 MGA with an attitude (and no voltage stabilizer)
http://MGAguru.com
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