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TR2/3/3A Ampmeter Reading - TR3

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spineguru

Senior Member
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My Ampmeter jumps all over the place, so it clearly does not work. It hasn't for years and it really is not a major concern to me. As long as it is jumping around, I am generating a charge (I know because the positive wire came loose from the battery once and the needle was dead still on "0").

My question is what should the gauge read if it were reading correctly? Also, if it is jumping around, is the gauge bad, or could it be something else? Thanks!
 
At Idle it will show a slight discharge (just under the centerline) a little more according to how many things are on like headlights or wipers.
As soon as the RPMs come up a little it should move over to the chargiing side. Again a little more depending on whats running.
It usually will show a higher current flow right after starting when the generator is recharging the battery from the startup, but it should settel down quickly.
A needle showing a high current flow usually indicates a problem (dead battery, bad regulator etc...) A jumpy needle may be caused by fluxuations in the generator itsself, or more likley by a voltage regulator with dirty contacts or other issues.
Pop the cover off the regulator and make sure the contact points are clean (it would be wise to disconnect the battery before you do this).
 
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(it would be wise to disconnect the battery before you do this).

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coward... /ubbthreads/images/graemlins/devilgrin.gif
 
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(it would be wise to disconnect the battery before you do this).

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coward... /ubbthreads/images/graemlins/devilgrin.gif

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They don't call me sparky for nothing /ubbthreads/images/graemlins/grin.gif
 
The needle on the ammeter in my TR4 used to jump all over the place. I started messing around with the voltage control box (trying to adjust the settings per the Bentley Manual). I only managed to make it worse! Ended up buying a new control box, and now it works great - nice and steady.
 
Are all your ground wires tight? Especially the ones for the other gauges on the dash panel. With only the engine running (no lights or wipers on) the needle should read the voltage that has been set as per the mauuals between 13 and 14 volts. With the light on at night, it may drop to zero or a bit below. More than 14 volts, your battery will flood acid out the top of the cells and ruin your steel battery box. It will also run the battery liquid level low quickly and you will need to be adding water more frequently. It may also spit acid all over that newly chromed valve cover you just paid a fortune to get re-chromed.
 
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