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All the help I have received with my odd problems have led to renewed TR driving, thanks everyone, you know who you are but I have another request.

Why does my Ammeter swing violently - to + and back again then settle to centre position intermittently. I have Dynamo electrics with narrow belt, adjusted correctly.

Any advice please?

Update..... The battery holds its charge.



Edited by Vic787
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The ammeter should only be responding to current flowing into and out of the battery.  Fluctuations like this may be due to switching on or off of some large load (cooling fan?)  but may also be a result of a problem with the dynamo or its control unit.  If the dynamo bearings, brushes and commutator are in good condition this is most likely a fault in the control box. That is not something to be fiddled with unless you really know what you are doing, but careful cleaning of the contacts with fine glass-paper may help, provided the mechanical adjustment is not changed.

Modern reproduction control boxes are known for unreliability, as the contact materials are often not to original specification. 

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There is available a control box which looks like the original but contains electronic parts.  From reports on the Forum, these seem very reliable (they ought to be) and probably better than (some) reproductions - see RobH's comment above.

I have no experience of these electronic versions - I have an alternator.

Ian Cornish

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The ammeter on these cars is a simple moving-iron instrument, and the do swing about a bit.

Before spending on the regulator, make sure all the connections on the dynamo, regulator, ammeter, solenoid are good. Don't forget the engine earth strap!


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