Amp gauge HELP!

DPV1936

DPV1936

Junior Member
So I get the Model A running but the Amp gauge is not showing discharge when I crank it over nor is it showing charge at all no matter rpm. New 6 volt battery reads 6.23 volts out of car. When car is running I show no voltage at battery. I bumped the cut-out with my hand and it sparked while the key was turned off. Then amp gauge started smoking( still with key turned off). Disconnected the battery (very quickly!!) but smoked the amp gauge. I have the battery hooked negative to starter, positive to ground (frame). When I got this car there was a 6 volt battery in the battery tray disconnected with the positive terminal closest to the starter but the cable would not fit over the positive terminal so I assumed the person just put the battery in facing the wrong direction. Is it possible this car was set up for 6 volt negative ground and could that be part of my charging problems?
 
Sounds like you need to check your wiring. Use this and make sure it is wired correctly.
 

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You would not see a discharge when cranking. The starting circuit except maybe the points, does not go through the ampere meter.
 
The starter switch is connected directly to the battery power so it won't peg the amp meter during start phase. When the cut out is bypassed it will try to motor the generator with engine off. It will get hot trying to turn the fan and crankshaft. Don't do that unless the motor is running. Even then, just do it momentarily to see if the generator comes on line.

A three brush generator is only set up for positive ground and I can think of no reason to go through the effort of changing that. If the generator has been reverse polarized then it needs to be polarized back to positive ground.

The little amp meters are OK for normal use but a big short will kill them. There's not much to the model A electrical system so it's a good one to learn on. A person just needs to check electrical connections periodically. They don't work well with any loose connections.
 
Thanks for all of the great info. How do you guys feel about the amp gauge actually smoking? Makes me believe a pretty big short. I ordered a new amp gauge, cut-out, new wiring from cut-out to terminal and new from terminal to dash. The wiring in those places had some burn spots so I am doing it new to make sure it is done correctly.
 
Generally speaking, a smoking amp gauge is not a good thing :eek:

An accessory fuse mounted to the starter is a good thing. If you don't have one, I recommend adding one ASAP. There is not a lot of room behind the ammeter or ignition switch. Make sure nothing is shorting against the tank. Did you get a quality ammeter like a Nurex? There are a lot of cheapos that are not very reliable. Same can be said of the cheap $20 generic cutouts some vendors sell. In general, buying the high quality electrical components is money well spent.
 
So there is a fuse mounted on top of the starter. Should that have blown before the amp gauge?
 
You may not have a fuse as it is a add on the vendors carry, they did not come with one from factory.
 
Check the voltage cutout and generator. I believe you will find your problem. You said your "bumped" your voltage cutout and it sparked. That's a problem. If it is the newer diode style, bumping it should have had no effect. If it's the original style, and it sparked, there is a short. The cutout is designed to disconnect the generator from the battery when the generator is not producing voltage greater than the battery voltage. Check the flag terminals and wiring at the cutout. That's probably what you saw "sparked". It's easy for that wiring to short against the cutout body or generator.
 
Rotorwrench, "A person just needs to check electrical connections periodically. They don't work well with any loose connections."

X2, the Les Andrews second book, the blue one, called "Diagnosis and Troubleshooting" has a voltage test that takes only a couple minutes to do. The test will let you know the general health of your wiring connections between the generator and the battery. The test is described in Chapter two.
 
GRutter touched on the cut out but we don't know what the OP has in that respect. There are three different possibilities of cut out types. The original is the electo-mechanical switch pole that automatically brings the generator on line as soon as the generator puts out a voltage above the battery voltage after engine start. Cut outs can sometimes stick in the closed switch position. The points can weld themselves together. If this happened then it could have fried the amp meter due to the short created either by trying to motor the generator or some other direct to ground short. The wire will burn or whatever else is connected in the circuit including the amp meter.

The second common type looks like a cut out but only has a power diode inside. As long as the diode is functioning as it should then it will only allow current to pass through to the system after engine start up. After shut down, no current can pass back to the generator from the battery.

The third but not as common type is the Fun Products voltage regulator that looks like a cut out. It has a diode set up as well as a basic electronic IC chip that controls the output voltage and current control. It is not easy to tell if one of these is installed since all three look like a cut out.

There is also a possibility that an internal regulator has been installed inside the generator. If the OP or other new owners of these cars have charging problems, they need to be aware of all the possible configurations they may have. If the owner is familiar with his car then this is generally known to them.
 
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rotorwrench said:
GRutter touched on the cut out but we don't know what the OP has in that respect. There are three different possibilities of cut out types. The original is the electo-mechanical switch pole that automatically brings the generator on line as soon as the generator puts out a voltage above the battery voltage after engine start. Cut outs can sometimes stick in the closed switch position. The points can weld themselves together. If this happened then it could have fried the amp meter due to the short created either by trying to motor the generator or some other direct to ground short. The wire will burn or whatever else is connected in the circuit including the amp meter.

The second common type looks like a cut out but only has a power diode inside. As long as the diode is functioning as it should then it will only allow current to pass through to the system after engine start up. After shut down, no current can pass back to the generator from the battery.

The third but not as common type is the Fun Products voltage regulator that looks like a cut out. It has a diode set up as well as a basic electronic IC chip that controls the output voltage and current control. It is not easy to tell if one of these is installed since all three look like a cut out.

There is also a possibility that an internal regulator has been installed inside the generator. If the OP or other new owners of these cars have charging problems, they need to be aware of all the possible configurations they may have. If the owner is familiar with his car then this is generally known to them.
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Rotor, thanks for your explanations. In paragraph 2, doesn't the power diode actually have a very small leak back (milliamps) that over a long period could drain the battery? Weeks or months?
 
FWIW - my preference is to use original Ford cutouts. They are not hard to find and are much higher quality than the repros currently on the market. Occasionally you'll come across one that is burned out or the tiny wire off the core is broken. But most that I've worked on simply needed the points gently dressed and a few adjustments made to get the points to align and get them to close at around 6.5 volts. There are 3 areas that may need adjustment. The point gap, the air gap and the spring tension. If the points are in good condition and it is properly adjusted, an original Ford cutout will give many years of good service.

Here is one I worked on recently. You can see how simple they are.
 

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