Learned something about ampmeters today . .

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Model T Ford Forum: Forum 2013: Learned something about ampmeters today . .
Top of pagePrevious messageNext messageBottom of page Link to this message  By george house on Thursday, January 03, 2013 - 09:12 am:

. . .and wiring diagrams, too. Some of ya'll call 'em ammeters but, because they measure amperes, I include the 'p'. First of all, not all circulating wiring diagrams are created equal. One switch loom diagram that had the yellow with black tracer from #1 terminal on the firewall going to the battery screw on the switch fried my ampmeter. Another diagram has this yellow with black tracer terminating to the outboard ampmeter terminal with the heavier, yellow battery wire terminating at the inboard ampmeter terminal. This caused a 'charge' to show on the ampmeter when lights were turned on and a 'discharge' when the engine was revved up. Then I learned that these new repop ampmeters - at least the smaller ones used on the later Model Ts - are manufactured with the poles or terminals wired up differently. So, when I attached the heavy yellow wire to the outboard ampmeter terminal and the yellow/black tracer + the switch crossover wire on the inboard terminal, the ampmeter worked as it should. Just my 2 cent observation.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, January 03, 2013 - 09:39 am:

Ammeter is the correct name, regardless of wire color and gauge, or whether it indicates amps, milliamps or microamps.

I often play with the English, like disturbutor, but a few words like ampmeter bug me...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Lodge - St Louis MO on Thursday, January 03, 2013 - 09:54 am:

Yes, the "p" is dropped for ease of pronunciation. It could have been left in the written word and dropped when spoken (hence silent, like the "p" in swimming), but apparently somewhere along the line, the spelling was made to match the pronunciation.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, January 03, 2013 - 11:06 am:

George:

Some of the original FORD ammeters were backwards. Generally speaking today all ammeters have a + marking on the side that goes toward the battery positive terminal but it really doesn't hurt the ammeter if it reads backwards until you notice it and flip the wires. Ford figured it didn't matter either I guess. I have several large ammeters that are Ford scripted that are wired opposite the "normal" way and internally there is no way those same ammeters could be wired differently so they clearly came that way. I am fairly certain Ford stated it was OK to do that so long as the meter polarity was then indicated. No doubt that decision was made when Ford was offered some backwards meters that were CHEAPER.

You need to check your wiring carefully since I don't see how shorting the #1 terminal to anything on the back of the switch except the magneto terminal could then in fact burn out your ammeter since connecting a HOT to a HOT gives zero current. To burn out an ammeter you have to have one side connected to battery HOT someway and the other side connected to something going to ground someway. You then need both of those "someways" to be very low in resistance to thus carry say 30 amps or so in order to damage the ammeter movement. Check carefully since whatever destroyed your ammeter is likely still there in the wiring if that is how it happened for sure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Thursday, January 03, 2013 - 12:19 pm:

Ralph - I agree with you. Amp meter instead of ammeter sounds about like speed meter instead of speedometer. I do have a problem with disturbutor and thermobarf,...ha, ha,....

I also dislike dizzy, diffy, tranny, carby and rad. I think it's because most of us "T" guys are poor spellers.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Thursday, January 03, 2013 - 02:57 pm:

George H,
Pay attention to what John Regan says. Electricity is funny stuff. It often doesn't behave how one might think. People that understand electricity will notice something that doesn't add up under the "normal" or "proper" conditions and will realize that there is something else wrong. That something else may be able to cause a more serious problem later, like setting the car on fire or blowing out another ammeter. High resistance shorts can do strange things, like change into full shorts or opens, can kill the engine unexpectedly or worse.
People that know electricity, know that when something doesn't add up (like an ammeter blowing out when it shouldn't), indicates that the wiring should be checked out to make certain there isn't a worse problem waiting.
And John R knows electricity as well as anyone I know today.
(Then again, sometimes an ammeter can just fail because of a defect that has been inside the ammeter for a long time.) But you do want to check it out for future safety reasons.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, January 04, 2013 - 10:34 am:

Out of the blue and probably dumb but is the batt installed correctly?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, January 04, 2013 - 10:54 am:

Slightly OT but Junior's company cleaned out the warehouse recently and I got these as a result. The left one's strictly amps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, January 04, 2013 - 11:09 am:

Check out the insulation on all the wires. I once had a car which I was driving on a freeway at about 65 MPH at night when suddenly all the lights went out. That was scary. A few minutes later the lights went back on. That car was a 41 Ford and it had a circuit breaker. So when the circuit breaker got hot the lights went out and when it cooled off they went back on. I traced the wires and found the taillight wire was touching the exhaust pipe. The insulation had burnt through and it made contact with that hot rusty pipe. The lights went out, but wind and road bumps plus the rust on the pipe it would only ground out sometimes. Taped up that wire and moved it away from the pipe and no more problem.

On a Model T if it is stock there is no fuse, so the ammeter being the weakest point in the wiring will burn out. Somewhere you have a wire grounded out. It could even be caused by a sticking cutout at the generator causing all battery voltage to go into the generator. Since the generator is not able to move, the current will go through the generator to ground and the ammeter gets hot and acts as a fuse.

So check everything. The problem could be anywhere.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By george house on Friday, January 04, 2013 - 03:41 pm:

OK . . . now I learned a third bit of information. Ain't no 'p' in ammeter. Thanks to all for the input - especially Mr. Fun Projects for confirming that some ammeters were built to where they don't conform to a wiring diagram. Now its incumbent on the restorer/hobbiest to look to the needle readings to determine if the wiring is correct. All the wiring is new and nothing looks as if its going to ground/earth. I did have to electrical tape up the crossover wire after the ammeter fried. Thanks guys


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