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Old 04-22-2020, 03:54 PM   #1
shew01
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Default Is there a way to reset the ammeter to zero?

I just had the instrument panel cover off to install a dash light, and I didn’t think of this question until I had everything buttoned back up. (Sorry, I should have thought of this while it was apart, but I was hesitant to rummage around too much for fear of introducing a short into one of the wires behind the panel. From what I have read, that area of the car can be finicky.)

The previous owner installed a power cutoff in the car. When the power is turned “off” in the car, the ammeter tends to “center” itself on -2, rather than 0. Is there a set screw on the back of the ammeter that can reset it to 0? If not, is there some other way to reset the ammeter to 0?


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Old 04-22-2020, 04:05 PM   #2
Jim/GA
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Default Re: Is there a way to reset the ammeter to zero?

No, there no screw to adjust it. Consider where it sits now (around -2) to be zero and mentally go from there.
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Old 04-22-2020, 04:24 PM   #3
johnbuckley
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Default Re: Is there a way to reset the ammeter to zero?

parralax may make the dirver see a different charge than the passenger!
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Old 04-22-2020, 04:33 PM   #4
Ernie Vitucci
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Default Re: Is there a way to reset the ammeter to zero?

Perhaps just put a dot of paint on the glass is that location so that you can always tell where the actual neutral position is. Ernie in Arizona
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Old 04-22-2020, 04:48 PM   #5
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Default Re: Is there a way to reset the ammeter to zero?

If you disassemble the ammeter you can bend the needle that much. The needle is rather thin aluminum, much like a throw away pie tin. It takes two pair of tweezers and a very light touch. You also need to watch how close it is to the face when you put it back together.

Not being a D'Arsonval meter movement, it is influenced by surrounding magnetic fields and the magnetic permeability of the car/panel/gas tank itself. The earth's magnetic field will also cause it to read slightly differently if the car is facing N-S vs. E-W. That said, you need to correct the needle the amount shown as 'off' before removal from the dash. If you set it to zero on the bench it may not show that when back in place!
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Old 04-22-2020, 04:50 PM   #6
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Default Re: Is there a way to reset the ammeter to zero?

The next time you have the dash out you can take the amp meter apart, tweak the needle back to zero. My glass in the amp meter became loose so I took it apart, in the process I tweaked the needle off of zero and then put it back. Don't drink a lot of coffee before working on the meter, shaky hands!
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Old 04-22-2020, 05:30 PM   #7
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Default Re: Is there a way to reset the ammeter to zero?

I had one yesterday that was not on zero when I held it in my hand, it must have become bent sometime, not sure where I got it from but I took it apart and barely touched the needle which is thinner than aluminum foil and it moved over to zero. You could get another one sometime and keep the current one as a spare if you don't want to mess with it since it is your only one.
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Old 04-22-2020, 05:41 PM   #8
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by johnbuckley View Post
parralax may make the dirver see a different charge than the passenger!

Yes, parallax does seem to be at play. When I sit in the passenger seat, the meter looks closer to zero.


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Old 04-22-2020, 05:44 PM   #9
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by Sunnybrook Farm View Post
I had one yesterday that was not on zero when I held it in my hand, it must have become bent sometime, not sure where I got it from but I took it apart and barely touched the needle which is thinner than aluminum foil and it moved over to zero. You could get another one sometime and keep the current one as a spare if you don't want to mess with it since it is your only one.

That’s not a bad idea. It would be nice to be at 0, but at least it appears to work. I hate to risk “fixing” it and end up breaking it.


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Old 04-22-2020, 05:44 PM   #10
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by MikeK View Post
If you disassemble the ammeter you can bend the needle that much. The needle is rather thin aluminum, much like a throw away pie tin. It takes two pair of tweezers and a very light touch. You also need to watch how close it is to the face when you put it back together.

Not being a D'Arsonval meter movement, it is influenced by surrounding magnetic fields and the magnetic permeability of the car/panel/gas tank itself. The earth's magnetic field will also cause it to read slightly differently if the car is facing N-S vs. E-W. That said, you need to correct the needle the amount shown as 'off' before removal from the dash. If you set it to zero on the bench it may not show that when back in place!

Wow. I didn’t realize the ammeter could be so variable.


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Old 04-22-2020, 05:45 PM   #11
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Default Re: Is there a way to reset the ammeter to zero?

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Don't drink a lot of coffee before working on the meter, shaky hands!
Good point.


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Old 04-22-2020, 10:45 PM   #12
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Default Re: Is there a way to reset the ammeter to zero?

Unless you are REALLY patient and can deal with little stuff that is somewhat delicate, I would not recommend you take the ammeter apart. You risk making the problem even worse, and the repop ammeters everyone sells don't fit in the instrument panel very well. I would leave well enough alone.
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Old 04-23-2020, 04:47 AM   #13
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Default Re: Is there a way to reset the ammeter to zero?

Make sure the needle pivot is free. With the needle out you might try slightly rotating the magnet ring inside the case. If it’s not an original one I wouldn’t even mess with it. Search for a decent original in Ebay or call Steve at Bert’s. There are many original ammeters out there. 25- 55 for a decent one is fair.
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Old 04-23-2020, 05:08 AM   #14
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by Magicbox51 View Post
Unless you are REALLY patient and can deal with little stuff that is somewhat delicate, I would not recommend you take the ammeter apart. You risk making the problem even worse, and the repop ammeters everyone sells don't fit in the instrument panel very well. I would leave well enough alone.

I’m beginning to think this is wisdom. If it’s not truly broken, maybe I should not try to “fix” it.


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Old 04-23-2020, 05:10 AM   #15
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by larrys40 View Post
Make sure the needle pivot is free. With the needle out you might try slightly rotating the magnet ring inside the case. If it’s not an original one I wouldn’t even mess with it. Search for a decent original in Ebay or call Steve at Bert’s. There are many original ammeters out there. 25- 55 for a decent one is fair.
That’s a thought. Thanks!


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Old 04-23-2020, 11:17 AM   #16
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Default Re: Is there a way to reset the ammeter to zero?

If you do not want to touch the needle rotate the face to zero,it won't be 100% accurate but now it won't annoy you.
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Old 04-23-2020, 07:19 PM   #17
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Default Re: Is there a way to reset the ammeter to zero?

One day someone will pony up and make a GOOD Model A ammeter, and I think people won't have any trouble paying 75 bucks for an exact duplicate, a quality ammeter.

The ones coming in from overseas are pretty bad. The better Model A suppliers will tell you that.
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Old 04-23-2020, 09:50 PM   #18
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Default Re: Is there a way to reset the ammeter to zero?

Lots of bandaid solutions so far. First, have you confirmed the position if the needle with no wires connected?
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Old 04-23-2020, 10:06 PM   #19
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Default Re: Is there a way to reset the ammeter to zero?

https://www.fordbarn.com/forum/showthread.php?t=20392

This is an old discussion about ammeters
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Old 04-24-2020, 05:15 AM   #20
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Default Re: Is there a way to reset the ammeter to zero?

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Originally Posted by Hitman View Post
Lots of bandaid solutions so far. First, have you confirmed the position if the needle with no wires connected?

Yes, the ammeter reads -2 then the main (aftermarket) power cutoff is turned off.


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