Lotus Elan and Lotus Elan Plus 2 Forums

Does anybody know how to change the dash clock from positive to negative earth.

Steve

I have taken the clock apart and found its a model 607B , as far as I can see its not polarity sensitive. It only has a resistor and a coil which magnetises regardless of polarity.

Picture below , Can anybody confirm my opinion , as I certainly no expert.

Neither am I an expert but I'm inclined to agree with your conclusion that the coil, ( which I assume momentarily winds what is otherwise a mechanical clock), won't be polarity sensitive.
I've fixed a few car clocks in my job as a clock repairer and I'm not sure if I've seen one of these or not.
I'm guessing that as the clock winds down a contact is made, which energises the coil, which kicks, and rewinds it, and the whole sequence starts again.

I would make the case the same polarity as the other instruments.
A little spot of thin oil at the end of shafts wouldn't be a bad idea, but don't put oil anywhere near the gears, and don't spray it with WD40......

Cheers
Ralph.

Hi Steve

The clock in my 1974 +2S130 was of the type that is a mechanical clock with an electric impulse rewinder that flicks a small spring tensioned flywheel around once every 2 minutes. After much use there may be some residual magnetism in the coil mechanism so it may not pulse exactly the same on the first pulse or two but should settle down. Also the build up of material on the contacts may change (bit like contact breaker points in a dizzy) over time with the polarity change over. Suggest when you swop you put a bulb such as 21W stop in series keep an eye on it and if the winder locks up the bulb would light so you could switch off B 4 any damage is done.

I made a protection circuit up for my clock so should the winder lock up the clock mechanism would not burn out. It was an article published in Club Lotus mag a while back

I have attached a copy if U R interested

hope this helps best of luck

bob