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Discussion Starter #1
I had a student put a new alternator on a 72 and when he was done we have no power at all. No dash lights, no starter etc. All I have had time to quickly check was that the starter turned on when I jumped it across the solenoid. Any ideas? I figure we lost power going into the dash so the ignition switch has no power, among other things. No headlights either for that matter.

Where to look first?
 

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Well - if it worked befor then I would look at the wires to the alternator for a start. Seems sort of odd. Time to get out the volt meter and start chasing it down.
 

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I'm not very electrical savvy but is there a fuse that could have blown causing the issue? Though I'm assuming the battery was disconnected during the process. Nothing got hooked up backwards did it?
 

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No power to anything usually indicates that you fried the Main Voltage regulator when you put in the new alternator. This is really common. The rebuilt Alternators of today are rebuilt to 1983 specs, (Which was meant for an Electronic Voltage regulator, not a mechanical one.) I've burned up tons of mechanical regulators over the years, and this is ALWAYS the case. Put in a new Electronic Voltage regulator, either a Motorcraft or a Standard Motor Parts unit (Don't use anything else, unless you want to be found dead on the road.) You can get them at Rockauto.com and NPD (NPDlink.com).

You'll be humming away in no time flat.

Tony K.
 

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No power to anything usually indicates that you fried the Main Voltage regulator when you put in the new alternator. This is really common. The rebuilt Alternators of today are rebuilt to 1983 specs, (Which was meant for an Electronic Voltage regulator, not a mechanical one.) I've burned up tons of mechanical regulators over the years, and this is ALWAYS the case. Put in a new Electronic Voltage regulator, either a Motorcraft or a Standard Motor Parts unit (Don't use anything else, unless you want to be found dead on the road.) You can get them at Rockauto.com and NPD (NPDlink.com).

You'll be humming away in no time flat.

Tony K.
That makes total sense. Glad I stumbled across this thread as I'm putting in a new alternator this weekend. Hopefully, no issues.
 

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Discussion Starter #7
No power to anything usually indicates that you fried the Main Voltage regulator when you put in the new alternator. This is really common. The rebuilt Alternators of today are rebuilt to 1983 specs, (Which was meant for an Electronic Voltage regulator, not a mechanical one.) I've burned up tons of mechanical regulators over the years, and this is ALWAYS the case. Put in a new Electronic Voltage regulator, either a Motorcraft or a Standard Motor Parts unit (Don't use anything else, unless you want to be found dead on the road.) You can get them at Rockauto.com and NPD (NPDlink.com).

You'll be humming away in no time flat.

Tony K.
HOw do you test a voltage regulator when the engine wont run? I've tested voltage output with the engine running before, but not on a non running engine.
 

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"How do you test a voltage regulator when the engine wont run?"

Of course it can be done, but for all practical purposes, You really can't. The engine has to be running. Point being, Dump the crappy old Mechanical regulator and put in a literally trouble free Electronic Voltage regulator. A popular idea is to take the cover off of the Electronic regulator and put on a Concours cover from a Mechanical regulator since the bases are almost identical. You'll get the vintage original look, without the vintage trouble. Ever get in your car and the interior lights dim or flicker? Well that's your crappy mechanical voltage regulator. You don't have "voltage drops" with an Electronic regulator. *Also, If you plan on upgrading your stereo or have some extra "accessories", Don't even think of using a Mechanical regulator, because it won't be in use for long with stuff like that.

With time, (And I am A die-hard correct restorer), You learn to make trade-offs for the sake of safety and reliability, and the Mechanical regulator is just such an example and one of those very things.

Such as for example:

Bias tires vs. Radial tires

Deadly single "Fruitjar" Master Cylinder vs. Dual Master Cylinder

Mechanical voltage regulator vs. Electronic Voltage regulator (Solid State- No moving parts, no points., etc.)

Get my drift? Ehh??
 

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no no no dont do anything dont replace anything. just experienced this on my car sometimes you have some problems with those wire grounding alternator. so what happened in my case was that i put in guage + line to the solinoid ON THE INSIDe of the solinoid on the power side. but i didnt have any black wire to do the negative so they wernt grounded. so i wasnt getting any cranking, no blower, lights, break lights. figured out what was round that positive battery cable has to be pushing up to the nut on the solinoid on the INSIDE OF the other wires. then i got crank after i did this. you should try that.
 

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Discussion Starter #10
Found the problem. When I finally got the DVOM I was able to find that the wire from the solenoid to the alternator was burnt up, but only on the inside of the wire. So the rubber was all intact, but after noticing that there was no resistance, I could feel that there was no write behind the rubber at one point. New wire and it runs like a champ.
 
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