Diode/Cutout Help Needed

[Tom Wesenberg]

If the generator is working correctly, then even on the lowest setting of the third brush it should show some positve ammeter reading.

A&L makes an excellent diode cutout with a large heat sink for those who want to go with a diode rather than original cutout.

[conservationist]

Originally Posted by midgetracer

Bob,
I am a little confused.. You said that you had clear continuity with the black on the generator and red on the battery, however later it sounds like you do not have a solid connection that way. You should have no resistance (total continuity) that way. Reversing the wires should read totally open. You don't need a high tech meter for these tests. Even the $3 Harbor Freight ones will tell you what you need to know. The black on generator and red on battery should look just like when you touch both leads together. If not, there is a bad connection. With the leads switched, you should have the same readout as with the leads not touching anything. Good luck Bob, and don't get upset with the problem. It will turn out to be something simple.

MidgetRacer -- Yes, I agree with your statement about an apparent bad connection. I may have stated my results poorly. I correctly have 0/zip/no connection with Red on generator and black on battery. In other words, the readout is the same on my meter as if I am not touching terminals together -- like I want or at least as I'm told it should be. BUT, when the leads are switched, the digital readout instead of going to 0 (like it does when I touch leads together) gives me a bunch of fluctuating numbers but they DO NOT drop to zero showing a connection. I've taken the solder joint apart, sanded and re-soldered with no improvement.

[conservationist]

Originally Posted by AL in NY

One thing I haven't seen mentioned in this thread is: third brush adjustment. Maybe you just need to increase the charging rate of the generator by moving the third brush. Just my two cents....

Unless little dwarfs snuck in and changed something, I had the third brush turned up to about 10 amps while testing the old cutout (I manually closed the points and made third brush adjustment). I just couldn't get the old cutout working so decided to "upgrade" to a diode since the after market cutout's don't seem to come very highly recommended here.

I'm assuming I can bridge across terminals with engine going and make sure I'm still getting gen output -- correct???? Although another post recommends just using meter and I can do that too probably with less sparks.

Thanks all for helpful ideas. I've had company so have not spent time under the hood.

[Tom Wesenberg]

You can just jump the 2 terminals with the generator running to bypass the cutout, even if it's a diode. I'd buy a good analog multimeter and forget about digitals. A lot of digital meter will jump all over by just looking at them! LOL Especially with the engine running there is so much electrical noise that a digital is worthless.

BTW, the diode won't read 0 since it has some resistance, even in the forward direction.

[conservationist]

Can't get under the hood time until afternoon Tuesday. Then I'll run some meter tests and see where I'm at. I know I'll get this figured out!!

[midgetracer]

Sponsored Links (Register now to hide all advertisements)

The ohms reading with black on the generator side and red on the battery side should not fluctuate more than one or two digits. It should show a bit of resistance as Tom had said, but the reading should be solid, no fluctuation. My thought is that your diode is open or a poor connection somewhere.

[conservationist]

Sorry I haven't been back on in a week or so. It has to be a bad connection. To get it on the road, put in an old, after market cutout and left the "top" off. It doesn't work, but after truck running, I can manually put points together to get generator sending a charge to battery. What is strange to me is that I have to often "polarize" the the gen to get it going. This needs to be done fairly often.

Anyways, have not figured out the diode. Model A meet here in Boise this week so will operate with the hands on method until I can figure something else out.

Thinking of just dropping the $100 and going with cutout looking regulator parts as this is a driver, not a show truck.

Thanks for all the help.

Bob

[Tom Wesenberg]

Before you do anything else make sure the generator is working correctly. You said you removed the cover on the cutout, so I assume it's a repro, as their covers are easily removed. You need to seperate two spot welds on original cutouts in order to remove the cover. Make sure the air gap of the cutout contacts is no more than .020" in the OFF position. To check the generator for output you can just jump across the cutout with a short wire while the engine is running. The generator should start showing a charge at about 475 engine RPM is it's working OK.