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MG MGB Technical - Dash Lights - Dimmer control - Is it needed?

Quick question...

The 'dimmer' control on my dash is cutting out intermittently. I have no idea why there is a dimmer in the first place as it isn’t exactly bright as it stands.

Anyway, I am thinking of bypassing this dimmer control completely so the dash lights are on 'full' when they are on.

Anything I should be aware of in doing this?
Will it effect any other electrics?
Is it straight forward to do?

Look forward to hearing your thoughts/advice on this.

Mark
Mark Duggan

Dead easy. You don't even have to pull the switch out. The switch has two terminals on each side of the variable resistance. Four prongs/spade connectors at the bottom of a D shaped housing about an inch or so across. Two wires connect to it, an in and an out. Just unplug one of the wires and plug it in next to the other wire. That will by pass the variable resistance . You can buy these new but they cost about $120, so because most people have them turned to the max all the time anyway, lots of people do away with them. Your light ends up slightly (maybe 5%) brighter, which is a good thing.
If you want to take the switch out, there is a tiny hole in the side of the knob. Push something thin in there and depress a spring loaded stop. Jiggle and pull the knob off. Then there is a nut to unscrew.

The only hard part is getting your hand in there. You might have to take out the speed or taco and reach through that hole
peter

I sprayed the rheostat (inside) with contact cleaner, works fine now. But like you, I leave them on full anyway. A good spray and a bit of back and forth may put it back to work.

Back when the cars were made, there wasn't as much glitz in the dash as there is today. Maybe they were thinking of a scenario on the bluff, overlooking the city lights, and those dash lights were a little intrusive at full power, but a little glow might make the mood a bit better.

Reminds me of the song about gein' a pickup man...the cargo light gives off a romantic glow...

Today it could be porn on the DVD while parked on lookout point.
Tom

I did as Peter said on my old GT. Was easy to do and there aren't any bad effects. I do have a dimmer pulled from some other Brit car at home. I have no idea if it works or not but if you desperately want a dimmer you can have it :)

Personally I say don't bother and bypass it!

Simon
Simon Jansen

Yep. Bypass it.


Rick Stevens

Another trick:

twiddle the knob all the way back and forward 100 times (or thereabouts). This cleans the crud from the contacts and brightens things up again. I just successfully did this on mine.
Curtis Walker

If you have a later RB model with the dimmer down the LH bottom then they have a circuit board in them that burns out so you will have to bypass it to get them working satisfactorily
Garth
Garth Bagnall

I have twisted it over and over and it just cuts in and out... annoying! So... I'm just going to bypass it.

Simon... Thanks for the offer of the dimmer. As I'm going to bypass it, I won't need it. Thanks anyway. Your offer is much appreciated.

As an aside, I think I will replace the switch with another and reroute my current ignition kill switch to here. I like the suggestions I had earlier of having it in plain site. By that... the most obvious place (right in your face) is the best hidden spot. Anyone looking for a kill switch would be looking for it in a typical 'hidden' position.

Thanks for your advice everyone
Mark
Mark Duggan

Depends on the year. Some have only two wires i.e. one wire on each side of the switch that leaves a spare spade each side, making it simple to swap one wire over to the spare spade on the other side and so bypass the dimmer. Other have two wires in different spade connectors meaning you have to be a bit more creative in joining those two to the other one.

Every car I have had came to me with a dim dimmer - it appeared to work but was less than fully bright in the fully bright position. Also all of mine have been of the printed circuit type not wire wound and part of the circuitry had burnt out. As I hate things that don't work I have always replaced them (at great expense) and after 20 years on one car (admittedly not much lights-on driving) and fifteen in the other (with lots of light on driving) none of them have subsequently failed ... yet.
Paul Hunt

I had the same problem on my 77B. I found rebuild instructions for the Panel dimmer on The MGB Experience website(www.mgbexperience.com/article/dimmer) Followed their instructions and the panel dimmer works like new.
A SCHNEIDER

This link works http://www.mgexperience.net/article/dimmer.html
Geoff Everitt

This thread was discussed between 21/08/2009 and 11/09/2009

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