No output from alternator

[Curious Hound]

Well I've got 2 alternators. The trick worked on the new alternator but I put the original back in and straight wired power to pin 1. It came on for a few seconds then quit. Maybe I fried it. So maybe some resistance is required to not do that. Anybody know?

Did you fry something? I’m not sure. That circuit does expect a certain amount if resistance. There is even a resistor in parallel with the indicator lamp so the circuit will function in the bulb blows.

 

[Conflict]

I put the new alternator back in and wired it through a 7.5 amp fuse and a 470 ohm resistor I had because the elec schematic showed a 442. No good. Tried 150, then 100, then just a bulb. No good. Straight from the fuse to pin 1 and it comes on and stays on and hasn't died yet. Volt reg will tolerate no resistance. So I'll find a key-on power source, send it through a fuse and call it fixed. I guess I'll put a voltmeter on the dash for info. The unanswered question is why can't i duplicate the circuit depicted in the electrical diagram?

 

[Conflict]

I'll take the alternator that I may have damaged down and get it tested.

 

[Curious Hound]

Are you sure you are getting full battery voltage to pin 1 through the normal circuit from the ignition switch? I'm not talking about checking it with a test light. This is a case where you need a volt meyer to give the actual voltage reading.

When you bypass that circuit with a jumper, you say the alternator works. So, that indicates that the normal circuit is faulty - loose or dirty connection somewhere or maybe even shorted to ground somewhere between the unducator light and the alternator.