The Stovebolt Site Forums The Shop Area The Electrical Bay altenator help, please anybody

I have a 59 Apache which was formally a 235 truck and when i bought it it had a 327 out of a 66 Chevy something (former owner didn't know what from). anyway here is my question, the alternator went bad. I when to the parts store bought a alternator that had an internal volt. regulator. I installed the alternator, plugged in the the terminal that had 2 wires(NOT SURE WHAT THOSE 2 WIRES ARE) and put on the single wire which I'm assuming is the ground. As soon as i had the battery hooked up, I had smoke coming from the alternator, and under the dash. Yikes. I quickly pulled the negative batter wire to prevent any damage, I disconnected the alternator and the truck still started so not to much damage. Anyway what could have caused this? Did i get the wrong alternator? Should i have gotten the one with an external regulator? I know longer have the old alternator caused i used that for the core. any guesses on what i should look for. Any help will be greatly appreciated, cause electrical is not my strong point. I can send out pictures of the wires and the new alternator. Thanks Josh

that big wire is NOT ground, it's your hot 12vdc to the battery. the other two are probably the DA plug wires #1 & 2. a three wire alt. the DA has an exciter wire that gets voltage from your system to the alt. the sensing wire is the other that let's the internal regulator know how much voltage the truck is using. the big fat wire provides voltage back to the battery. the housing is grounded thru the fastening 'bolt'. the truck started because the battery still can turn the engine over and provided voltage to/thru the system to the dist..
did you take the old alt to the parts house and got one just like it?

The alternator I got looked like the old one,it was all a visual thing..the old alternator was worn and beat, had it tested and it was bad. so i told the parts guy i needed a alternator for a 66 Chevy 327 2bl. For argument sakes how would i know if i needed an alternator with an external volt. regulator?would it not have the DA wire plug?I can return the alternator and get another one, but what should i get?.... The only reason why I disconnected the alternator and started the truck was to see how much damaged i caused after the smoke show.

JAWDY,

The two alternators in question look sort of the same, but the DA plugs are different, have different pin configurations and won't interchange. If you actually got the DA plug on the truck to snap into the receptacle, you have the proper alternator.

There is a small screw on the alternator housing that is used for a ground. Few people use it and it's not a big, fat obvious attachment point.

As Jim alluded to, maybe you did attach the post, which is big, fat and obvious to ground. This might have let the magic smoke out of your new 'dynamo'!

When you removed the old alternator, it should have had three wires...some kind of DA plug AND a big fatty with a ring terminal on the end. If you plugged the DA into the new alternator, what did you do with the other large wire. It should have attached to a large red insulated lug on your new alternator that might have said BATT.

These three wires are common. A fourth ground wire would be pretty uncommon but not unheard of. Does this make sense.

Most stores will not take a return on electrical items...unless they're friends or you're a real regular customer. Good luck and keep us posted.

Stuart

Makes sense. I would say my power wire is not a big fatty wire,that could be a problem, its kind of small. But the DA plug snapped in and i put the power wire on the red insulated lug. Do you think that if somehow the power wire touched the DA plug some how that it let the magic smoke out? I think i could somehow take the alternator back, it has a 1 yr warranty.. Just have to come up an excuse. How would i know if i did damage to the power wire or DA wires? No real obvious sings of damage... Other than the battery not charging, what would be a sign of damage?...josh

JAWDY,

What a tough call! Again, if the DA plug, which is 'polarized' to some extent, it only snaps in one way, fit properly, then the assumption is that you have the proper unit. Touching the power wire to either of the other wires shouldn't have been possible, and if possible, should have caused no problems.

If the wires in the engine compartment still have intact insulation and aren't burned or cooked, they sound fine. For any system to smoke so instantaneously, large amounts of current had to flow, especially if the smoke was from cooking insulation.

Something is wrong! I don't know what and it probably needs to be discovered before sacrificing another alternator. The only way the alternator could have caused this is if it had a power diode shorted to the case/ground, and when you hooked up the battery, you complete a dead short through the under-dash (ammeter?) wiring, through the power wire on the alternator to the case and then ground.

If you did some detective work, you might find a track to ground the power took through the mounting attachments.

This is all speculation, I don't know for sure. You do need to find out for sure what happened before you try it again, this circuit isn't fused and is capable of burning your Apache to the ground.

Stuart

Could you have the bat. hooked up backwards.