Thanks for your help, Wayne. I was out working on the car last night
and I picked up the rheostat (shaft removed--MY WAY OF GETTIN' IT OUT)
and looked it over a little. A little shake revealed little
pebble-sized pieces of what looked like black bakelite and broken
yellow "glass." I figured it was shot then.
Next questions:
1) Can a rheostat short out? I don't think it's the source of my
problem, but would gozinta burn if gozouta is shorted? Vice versa?
2) Also, I'm chasing burned wires under the dashboard and it seems
that some red wires with white tracer (panel illumination) are fried
(clock and oil pressure gauge illuminators). It may sound random, but
is there ANY way this could be related to a short in the white wire
that goes to the fuel pump?
3) Under the dash, are black wires ground wires? (My Bentley manual
hasn't come yet)
Any help will be GREATLY appreciated.
Thanks in advance,
Jason
______________________________ Reply Separator _________________________________
Subject: Re: rheostat--help!
Author: Wayne Kube <wkube@iadfw.net> at Internet
Date: 6/23/97 11:13 PM
Jason_Wood@inc.com wrote:
> Questions regarding the Panel Rheostat,or dashboard light dimmer
> switch.
>
> 1) How do you get it off the dashboard?
Jason - You remove the knob from the shaft, then you should be able
to unthread the chrome nut from the body of the rheostat.
> 2) If I have pulled the knob off (shaft and all) have I broken
> it?
Probably. I took apart my old one, and looking at the design, if the
shaft came out of the body, it's ruined, most likely. The knob is held
on by a spring loaded pin on the shaft. If you look at the side of the
knob, you should see a hole into which you can insert a small diameter
punch or a nail and press the pin to release the knob.
> 3) How does this thing work (where does the juice go in? where
> does it
> go out? What happens to it while it is in there?)?
There are two terminals, they are interchangeable. Call one the
gozinta, the other the gozouta. The juice goes in the gozinta, a
portion gets converted to heat by the internal resistance, and the
remainder goes out the gozouta. That goes to the instrument lamps.
> 4) Why is it so expensive to replace?
Because it's Lucas? because it's a poor design inside? Because the
internals are made of Rarium, not yet decayed into Unobtanium? Because
there is low demand for more of these? Take your pick.
> 5) Can I go without it for now and still have headlights and
> dashboard
> lights?
Definitely. After I bought a replacement for my old, locked up
rheostat, I found that I run it at full brightness anyway. The lights
really aren't very bright. So, you would just connect the two wires
together - this would give the same effect as the rheostat at full CW
rotation. Headlights aren't effected by it anyway.
This is what stopped me from designing a solid state 3 terminal
regulator replacement. I was going to incorporate this into the old
shell, but realized that I would never have any need to run the
instruments any dimmer than full brightness, so that project ended.
All of the above apply to my '79B - YMMV.
--
Keep on keepin' on!
(non illegitimus carborundus)
Wayne Kube 1979 MGB
Plano, TX http://web2.airmail.net/wkube
Texas MG Register http://www.tmgr.org
NAMGBR UK Site http://www.mgcars.org.uk/namgbr
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