Need alternator advice

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FlyWright

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California Delta
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FlyWright
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1977 Marshall Californian 34 LRC
I got my fried Balmar rebuilt with Balmar parts and installed and all is well. It's charging like a bull. As it turns out, my temp sensor was connected to the ground terminal which works on most alternators but not this one due to its offset position on the Balmar 621. Thanks to CMS/Rod Collins for alerting me to this issue and advising me on the best mounting position for this temp lead on the side of the case.

Here's a pic of my old port alternator. I'm replacing my working original (to me) alternator on the port side with a new single-wire alternator which has an AC terminal for the tach output on the case. The old alternator is wired with a block mounted on the back (orange and white wires) and a plug on the side marked 1 2 with the same white wire and a green wire. Both the orange and the green wire are 12V+ with the key on and engine not running.

Which is the tach output wire? What should I do with the other, unused orange or green wire? :confused::confused::confused:
 

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Can't answer your question, but wonder if you could deduce the answer by disconnecting the wires one at a time and seeing what stops working.

Ted
 
I got my fried Balmar rebuilt with Balmar parts and installed and all is well. It's charging like a bull. As it turns out, my temp sensor was connected to the ground terminal which works on most alternators but not this one due to its offset position on the Balmar 621. Thanks to CMS/Rod Collins for alerting me to this issue and advising me on the best mounting position for this temp lead on the side of the case.

Here's a pic of my old port alternator. I'm replacing my working original (to me) alternator on the port side with a new single-wire alternator which has an AC terminal for the tach output on the case. The old alternator is wired with a block mounted on the back (orange and white wires) and a plug on the side marked 1 2 with the same white wire and a green wire. Both the orange and the green wire are 12V+ with the key on and engine not running.

Which is the tach output wire? What should I do with the other, unused orange or green wire? :confused::confused::confused:

On our Perkins 6.354 Motorola alternator ,which looks like yours, the tachometer wire is the in the plug where the green wire is.
 
Is the green wire the tach feed...or the white wire?
 
Is the green wire the tach feed...or the white wire?

I'm assuming the white wire is the voltage sensing wire since its going to a resistor on the back of the alternator so the green must be the tach feed.
My alternator has a plug with 3 wires. 1, the voltage sense wire, goes directly to the output cable to monitor the battery, another goes to the ignition switch to energize the field and another goes to the tach.
 
I agree with Ted's idea. Release the green from the plug & see if that doesn't make the tach quit.
 
"wonder if you could deduce the answer by disconnecting the wires one at a time and seeing what stops working."


If the output of a working Alt is removed from the batterys , the diodes will usually stop working , till replaces.
 
I have to agree with Mr. FF- removing wires from a running alternator is really risky. Any troubleshooting where you're removing or switching wires "to see what happens" isn't good troubleshooting. Rather, do some research or ask someone who knows. If you get some agreement from multiple sources about which connection does what, you'll have a better chance at success. There's certainly some qualified information out there to guide you, do your homework.
 
Thanks guys for the input! I'm still in a holding pattern waiting to see if it's the green or the orange wire that provides the tach feed. I tend to agree that it's the green and the Balmar installation on the stbd side seems to confirm that but the wire has been spliced in a tight bundle and I haven't opened it up yet for a verifying peek.

I did disconnect the connector with the white and green and the alternator did not produce power or tach info. When I disconnected the orange, I got the same results.
I did each of these with the engine off and then restarted the engine. Fortunately, the test did not blow any diodes as all works fine when reconnected.

To avoid damage, I'll hold off on more 'experimenting' until I know more about what I'm doing.
 
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