Ok, I know this has all been addressed before, and I have read most of those particular threads. My problem is a wee bit different though.
Recently I've been doing some minor things to the car and so took on cleaning up the generator (a not so simple task, I had to take it apart to clean it up because I forgot I used sealed bearings when I rebuilt it 30 years ago...and oiled it...Ddho!). I used the MTFCA's Electrical Manual and did everything they said. I put it back into the car got everything hooked up and thought I'd adjust that third brush like they said in the book, by running the car and turning the headlights on, the adjusting it until the ammeter read zero. That WAS my intention, however, starting the car, the ammeter read "Discharge" at about 5 amps and when I turned on the lights it went to zero, exactly opposite of what it's supposed to do.
Now I figure it really is charging, but the ammeter is showing it doing just the opposite, because for the life of me I can't figure out how turning the lights on should move the needle in the direction of "Charge", so I figure the wires are backwards on the ammeter. Is there any reason this should happen? I mean are Model A ammeters backwards from Model T ammeters? I didn't think so, but if I reverse the wires it does exactly what it's supposed to do...is there something I'm missing here? George Clipner asked if I polarized it (something the book didn't mention at all) so I tried that today and it is still doing the same thing when wired like the schematic says its supposed to be wired, but if I reverse the wires (on the ammeter) then it behaves like it's suppose to.
Please, does anybody know what the bloody hell is going on here?
I don't know what is going on, but I know how to tell. Put a volt meter on the battery. If it is really charging, the voltage will be greater when the engine is running than when stopped. If you determine that it is really charging, then reverse the wires on the ammeter.
Make sure the cutout is working.
Neil
Martin,
You wrote : "...it is still doing the same thing when wired like the schematic says its supposed to be wired..."
and
"...I have read most of those particular threads..."
There appears to be different wiring schematics available - some with errors. If you haven't seen this thread
http://www.mtfca.com/discus/messages/257047/283501.html
please take a look at it, especially Ron's entry about 1/2 way down.
It appears that you did a good cleaning job, but the wiring outside the generator is wrong...
. -Good Luck!
I bet the battery is installed backwards. Model T's are negative ground.
Could it have the field coils wired backwards? Some of the field coils are not supposed to be crossed.
Good point Doug, if Martin replaced the fields - I've run into those fields. The Model A is positive ground and the available repro ammeters ARE wired reverse of that of a T. You didn't mention reversing wires at the ammeter prior to your generator cleaning so we're kind of guessing here.
Forgot to mention. To check the cutout, measure the voltage at the generator terminal when the engine is stopped. Should be zero, or very close to it, not the battery voltage.
To polarize, spark the battery voltage to the third brush while running. Do this only if you need to. If the generator is generating, judging by the increase in voltage at the battery when running, you don't need to polarize.
Neil
In your original post, you told about cleaning the generator and taking it apart and putting it back together. You didn't mention anything about whether you removed the ammeter or changed the wiring at the ammeter. Also did you have the battery out or just take off the cables?
If you didn't do anything at the ammeter or battery, than you can deduce that the problem is in the generator. However if you did disconnect the ammeter and remove the battery, then the problem could be there.
Both the battery and the ammeter of a Model A are opposite the T. The T battery is negative ground. If your battery is negative ground, then reversing the wires on the ammeter should solve your problem.
One other thing about the generator, is if you took out the brush plate from the generator when you were working on it, you could have it adjusted incorrectly. It should not "motor" with the 3rd brush pulled off the commuter. If it does motor, loosen the four screws and adjust the plate to find the null point where it does not move in either direction. Then tighten the screws.
Norm
Norman, I took the generator apart, but I also dismantled the battery and ammeter from the car for use on the test bench, so yes I did remove the wiring from the ammeter, the electrical book showed a test bench hookup using the ammeter and the battery. But I made sure I rewired it exactly as the schematic showed and I've checked it three times now, everything is correct from the back of the instrument panel to the terminal block and from the terminal block throughout the car.
Dave, I checked out his diagram against my car and with the exceptions of some wire color differences they are wired exactly the same, so I don't think it's my wiring, but I haven't completely ruled that out yet either, there may be a short somewhere in the wires, although I've checked and re-checked for continuity and they all seem to be in good shape.
Doug, I didn't remove the field coils or their connections, I just removed the armature and cleaned up all the gummy and burnt oil residue from inside the generator and off the commutator, then I dressed the grooves to make sure they were nice and deep, made sure there were no shorts and put it back together. Rotated the brush ring to the neutral point and re-installed the generator back into the car. The electrical book didn't mention anything about polarizing it, so I didn't, until George Clipner asked me about it. I read up on how to polarize from couple of threads here (one in 2010 and one in 2009). But that didn't seem to make any difference at all.
Royce, I'm not that green as to hook up the battery backwards, I've had both Model A and Model T and know the difference betwixt them, which is why I was wondering if mayhap the ammeter is different. The ammeter I'm using is out of a Model A (my Model T ammeter gave up the ghost a bit ago). I'm using this ammeter until I can get one of those fancy new ones (lighted maybe, haven't decided yet ) from Fun Projects.
Neil, I filed the points on the cutout, because they were pitted and sticking, they seem to be working correctly now (no sticking), I've got the cover off so I can watch what that bloody little trinket is doing, but I don't trust it though.
Back when I first got started (30 years ago or so) nobody was over worried about wither an ammeter worked or not, their test for a "good one" was to pick one up and shake it, if the needle moved back and forth, it was figured to be good, but I'm beginning to think these little buggers are perhaps a wee bit more important than anybody used to think. I'm beginning to think that if trouble comes up it'll show up on the ammeter.
I'm trying to get everything working right so I can get me one of those voltage regulator from Fun Projects, I'm sold, sounds like a good idea!
Just swap the wires on the ammeter. That's your problem.
Model A ammeters are set up for positive ground so they will read backwards if installed in a T. Jerry is right on the money, just swap the wires.
I think Jerry and Royce have hit it on the head. If your generator was really discharging the battery and you turned on the headlights, I think they would be very dim. A quick check would be if you have a DC voltmeter with the engine off, check the voltage on the wire leading to the cutout from the terminal block. Then start up the engine with the engine running fast enough to cause the ammeter to move and the voltage at that same point should be higher than it was without the engine running. If it is higher, your generator is charging and all you need to do is reverse the wires at the back of the ammeter.
Norm
Oh goody, I was hoping it was something simple like that, thanks guys.
LIKE
Unless you moved the headlight wiring to the wrong side of the ammeter the problem can only be a backwards battery or backwards ammeter since you said that when the car starts it runs as 5 amps discharge and turning on the lights moves the ammeter to 0 which indicates the lighting current is going backwards through the ammeter. If lights are wired to wrong side of ammeter then lighting load current shows as additional charge current but he didn't move any wires other than the ammeter and battery so it has to be one of those that got reversed. Small ammeters come both ways for both A and T. I have a collection of ammeters and you can find them wired opposite both with and without Ford script and only the T used Ford script. I probably have at least 25 ammeters that I started to collect when I decide to make T ammeters and several of those are large Ford Script ammeters and a couple of the ammeters are wired "backwards" from the rest. Clearly there was a "normal" way they came wired but some got out the door wired backwards and I think for a short time Ford would allow either way so long as it was marked.
Here is a way to check things out. Go to the battery and be sure the negative is grounded. If it is backward, turn it around so that the negative is grounded. Then hook up the ammeter. Connect the hot wire from the battery to one side of it and the headlights to the other side. Leave the engine off. Turn on the headlights. The ammeter should show discharge. If it does, the ammeter is correct. If it goes to charge, you need to reverse the wires at the ammeter. Now connect the wire to the generator to the same side as the headlights. Then start up the engine. The ammeter should show charge with the engine running at a fast idle and the lights out. Now turn on the lights and the ammeter should read 0 or small discharge depending on how you have the generator set.
Norm