Dancing Ammeter

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Michael Greenspan
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Dancing Ammeter

Post by Michael Greenspan »

After the roughly 500 mile round trip cruise to the Tom Yang East party, I have gained much more confidence in the car. There is a small issue that seems to have gotten a little worse. The ammeter dances between +40 and -40. Sometimes it is a slow back and forth of only 1-2 amps and then suddenly wing- wing- wing and then after a while maybe a 10 amp oscillation. It seems to have nothing to do with speed and the battery seems to be charged and to stay charged. Is it the Voltage Regulator or something else? Any ideas?? Thanks

Michael
1963 330 America #4969
whturner
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Ammeter Fluctuation

Post by whturner »

Does it do the same while the car is stopped but running? If so, you might find the problem more readily. Bypass the voltage regulator to see if it stops - this woulld overcharge the battery if continued for very long, but if the fluctuation quits, the Voltage regulator is at fault. Otherwise start looking for a short or bad connection, especially in the charging circuit, If you are lucky it will be the voltage regulator.
I don't know if Ferrari has circuit breakers - If my '47 Ford did that it would mean a short, which the circuit breaker is responding to, disconnecting and reconnecting the affected circuit. The ammeter goes crazy when that happens.

Cheers
Warren
330 GT Series II sn 10069
Lowell
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Post by Lowell »

It could well be that you need a new voltage regulator.

But the first thing to do, I think, is to find the fuse for
the regulator, take it out, clean the fuse end and also
the contacts in the fuse box from which it came.

While you're at it, you might as well do this for all the fuses.
All the cleaning should be done with a fine little wire brush on a
Dremel tool or some fine steel wool, and done very thoroughly.
Lowell Brown
1966 Gold 330 2+2 Series II
donv
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Post by donv »

My ampmeter did something similar for a while. I actually had the meter rebuilt, but that didn't fix the problem. I ended up rebuilding the alternator, and the problem is gone.
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Art S.
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Post by Art S. »

Michael,

Welcome to old car electrical gremlins! I agree with the above posts. However, also check for loose connections and carefully inspect the fuse block in addition. I have a funny feeling this may have something to do with old italian wiring and dirty connections.

Regards,

Art S.
1965 330 2+2 series 2 7919
Michael Greenspan
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Dancing Ammeter

Post by Michael Greenspan »

Thanks for the suggestions.

Actually, after an earlier electric problem I followed another threads advice about cleaning the fuse contacts and spent maybe an hour or so carefully removing the fuses one by one, dremel tool cleaning the fuseblock contacts and lightly sanding the fuse contacts and then putting them back with some conducting stuff. The difference in the car electrics was immediate and stunning. My electric fuel pump had always been a maybe this pull gets it to start and maybe the next pull does and when it started it would click half heartedly. After the fuse cleanup, the pump starts the first time I pull the switch and clicks away as if it were trying to set a new world record for float fill.

I have become an evangelist for the simple fuse maintenance routine!

I will try the suggestions about the regulator, which is my own suspicion. Could someone give me a clue as to which of the blocks on the electrical block it is? When the charging system seemed to go dead, I pulled the Alternator and what I thought was the regulator but I think I pulled the overdrive relay instead of the regulator. I never found out because a broken wire on the alternator was the obvious problem.

Michael
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tyang
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Post by tyang »

Hi Michael,

The Regulator on our cars is located under the passenger side dash behind the glove box.

Tom
'63 330 America #5053
Michael Greenspan
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Dancing Ammeter

Post by Michael Greenspan »

Thanks Tom. That's suuch an obvious place that I wonder why I missed it and thought it should b with the other electric stuff on the firewall block. I suppose this means that you have to remove the glove box?

Michael
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tyang
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Post by tyang »

Hi Michael,

Here's a shot of my regualtor under the dash:
Image
From the look of it, it looks like it might come out without removing anything.

Tom
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Michael Greenspan
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Dancing Ammeter

Post by Michael Greenspan »

Thanks Tom. I'm back in New York, so the look will have to wait until next weekend. Hopefully, you are correct.

Michael
1963 330 America #4969
Michael Bayer
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Post by Michael Bayer »

And replace all fuses with Buss real glass German style fuses saving all those primordial lead strip dillies for concours
kare
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Re: Dancing Ammeter

Post by kare »

Michael Greenspan wrote:Actually, after an earlier electric problem I followed another threads advice about cleaning the fuse contacts and spent maybe an hour or so carefully removing the fuses one by one, dremel tool cleaning the fuseblock contacts and lightly sanding the fuse contacts and then putting them back with some conducting stuff. The difference in the car electrics was immediate and stunning.
I would replace the fuse holders; local moto-market sells them for 6,50 euros each. Best wishes, Kare
250 GT 2+2 3197/GT
Jimmyr
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Post by Jimmyr »

The problem you have with the bouncing ammeter is a common one with the Marelli transistor regulators. If you have cleaned all of the connections as outlined above: a rebuilt regulator is required. These Marelli units were a poor design but the rebuilt units have corrected this flaw. DO NOT ever jumper any wires on an alternator system as you can damage the regulator. This is OK to do on a generator car. Rebuilts are stocked by the usual sources. Jim
Michael Greenspan
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Post by Michael Greenspan »

Thanks Jimmy. I will clean everything and send the unit out to be rebuilt. Is there a highly recommended Ususal Suspect? Again, thanks very much.

Michael
1963 330 America #4969
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tyang
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Post by tyang »

Hi Jim,
The problem you have with the bouncing ammeter is a common one with the Marelli transistor regulators. If you have cleaned all of the connections as outlined above: a rebuilt regulator is required. These Marelli units were a poor design but the rebuilt units have corrected this flaw. DO NOT ever jumper any wires on an alternator system as you can damage the regulator. This is OK to do on a generator car. Rebuilts are stocked by the usual sources. Jim
Does this hold true for any of the Marelli alternator systems including the more modern twin alternator systems? I just recently saw a Boxer with both alternators fried after being jumped, and we assumed the owner crossed the wires, but could it be possible it was hooked up correctly, and it still fried? Our electrical guy said the amount of internal damage could only have been from crossing the wires.

Tom
'63 330 America #5053
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