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MGB MGB Panel Light Dimmer

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kyreb1862

kyreb1862

Jedi Knight
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I saw an article once about rebuiding the panel dimmer. Would anyone happen to have a link to that particular article?
 
Best way to rebuild: B-Y-P-A-S-S it! /ubbthreads/images/graemlins/wink.gif

Mickey
 
I am sure your right Mickey but I'm hard headed and think if it is on the car that it just has to work! /ubbthreads/images/graemlins/tongue.gif
 
YAY JOHN!!

Yours is column mounted and easy enuff to get to, yes?. A good spraying into the unit after removal, with "CRC 2-26" or any good "plastics safe" tuner lubricant would be the first thing to try. Not sure about your particular one but it's just a potentiometer. Usually the "brush" gets mucked up and contact is sporadic or lost. Be glad you don't have the "older" unit. Requires three extra elbow joints to remove.
 
Ya mean like on a '67?
 
Yup. Fun, innit?
 
My dimmer is mounted in the dash. It is just frozen up. I can't get the knob to turn. I'm goin to take it out and try a little lube on it and see if I can get it un stuck.
 
Hey, that's what mine does! (or doesn't do)

I was going to leave it since the dash lights work, now i can see how much fun/pain this job will be!

Good Luck. /ubbthreads/images/graemlins/smile.gif

Rob
 
[ QUOTE ]
Hey, that's what mine does! (or doesn't do)

I was going to leave it since the dash lights work, now i can see how much fun/pain this job will be!

Good Luck. /ubbthreads/images/graemlins/smile.gif

Rob

[/ QUOTE ]

Keep watching. I'll report as I make (or don't) progress.
 
I assume you have the dimmer control with the "resistor" circuit card (Moss P.N. 146-300). The unit in my '78 B wasn't jammed, but it had only a very small range of dimming before the lites would just shut off. The device has a metal plate riveted to a zamac body casting. Grinding or carefully chipping off the rivetting will enable removal of the plate and reveal a phenolic circuit card with a pattern of resistance foil on which the wiper blade moves in rotation to connect various diminishing resisitances into the circuit. Its possible some of this foil has been burned through and the wiper has picked it up and jumbled it into a blockage that won't allow the shaft to be turned...could also be the zamac casting corroding or deteriorating and binding the shaft...try a bit of penetrating oil from the outside. If the card does have damaged foil, it might be repaired with some judicious lite duty soldering...bridging burned out spans with a small glob of solder. Use a very active liquid soldering flux sparingly just at the desired spot to facilitate good bonding...and a magnifying glass or some sort of magnification lite or hood is helpful to see the small working area. My repaired dimmer has been working fine...under test conditions...I prefer brighter dials so don't ask the dimmer to do much dimming. From the purist's perspective, a working dimmer brings satisfaction and it can always be shown to an appreciating colleague then turned up bright for running. After repairs, prepare the two rivet bases in the body for drilling and tapping...I recall using 2-56 round head screws...or maybe the next size up. I do a lot of model rail stuff and have the small tools to do this work but they are not expensive.

Bill
 
Now for the repair work followup. After some careful application of WD40 to the shaft of the dimmer, and then a little soaktime, I took a pair of pliers, padded the jaws with a piece of an old towel and then applied pressure. A little gentle pressure and soon the dimmer knob was working. Guess I got lucky. The lights now dim and brighten like they should. Thanks for all the input guys! /ubbthreads/images/graemlins/thumbsup.gif
 
Isn't it amazing that so many of the problems with our "terribly undependable" LBC's are actually minor and nearly always have simple fixes? /ubbthreads/images/graemlins/thumbsup.gif

Glad it worked out for ya!

Mickey
 
A little love is required from time to time.
 
I'd say still get some CRC 2-26 or equivalent "tuner lube." WD-40 is not a lubricant of any significance: "Water Displacement"...

CRC 2-26 is an elecrtronics/electrical lubricant. Plastics safe as well.
 
Thanks for that suggestion Doc. I'll hit Radio Shack this weekend and pickup some. I used to buy it there when I was fooling with model trains a lot.
 
I suggest replacing the rheostat with a push-pull switch like the one for early map lights. Then put the rheostat knob on it. You will not be able to tell the difference visually, but will have full brightness, which is all you really need since they aren't that bright to begin with. And it retains the ability to turn the lights off if you desire.
 
for driving under the cover of darkness obviously /ubbthreads/images/graemlins/grin.gif
 
My PO hardwired the panel lights into the headlight circuit so if the headlights were on, the panel lights were full on. I found a convenient hole into which I installed a rheostat with an appropriate range and wired IT into the headlight circuit. Works like a charm.

Guinn
 
[ QUOTE ]
My PO hardwired the panel lights into the headlight circuit so if the headlights were on, the panel lights were full on. I found a convenient hole into which I installed a rheostat with an appropriate range and wired IT into the headlight circuit. Works like a charm.

Guinn

[/ QUOTE ]

/ubbthreads/images/graemlins/lol.gif Now he can REALLY dim his headlights for oncoming traffic. /ubbthreads/images/graemlins/jester.gif

R.
 
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