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Mercruiser 120 82 Alternator issues

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barneythegaurdcat

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The alternator is currently pushing 70 volts.. we changed it to another one we had lying around the shop and it is still pushing 70 or so volts... Any ideas would be very helpfull
 
try another multimeter
it's not 70V
at 70 volts, the engine wouldn't run long enough to even take a reading before the coil had a meltdown
 
Actually theres a fuse between the two that is blown and keeping it from destroying the rest of the electrical system. Its reading 70v i assure you but it works perfectly when not hooked up to the engine (on test stand)
 
well the regulator controls the excitation... it senses voltage at the terminal marked "2"
image015.jpg

there were 2 alternators for that model in 82, a Delco, or Motorola, those are Delco markings - not sure about the Motorola

so you may have an open in that wire - follow it back - should have 12V with key on

top part of this schematic all you need to worry about - note how sensing connects to batt +
DelcoSI.jpg


middle row, rh side is the Delco
alternatorwiring.jpg
 
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Actually theres a fuse between the two that is blown and keeping it from destroying the rest of the electrical system

post a pic or give a better description of this fuse.
 
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