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Voltage Regulator Melting

75Cordoba

Member
Local time
3:49 PM
Joined
Jan 16, 2021
Messages
12
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10
Location
Englewood, Fl USA
Hey all,
I hope someone came help me with an issue on 75 Cordoba. I recently replaced the vpltage regulator because the back melted out of it, well my new one has the back melting out of it now. I had heard if they're not grounded well that would cause the issue. Checked ground point with an OHM meter an tested out with full continuity. Installed new 60 amp alternator about two weeks ago. I figure with all the knowledge hear someone has ran across this already and I'm overthinking the the problem. Any help would be greatly appreciated.
Thanks
Ron

IMG_20210129_144456042.jpg IMG_20210315_182350077.jpg
 
The voltage regulator controls the current and voltage flowing thru the alternators rotating field connections. The supply voltage flows thru the rotating field and back to the regulator to ground, thru the internal components. The regulator is also supplied with the battery's reference voltage thru the blue wire to the regulator, to allow the regulator to know or reference the charging rate. IF, the alternator's rotating field or rotor circuit current draw exceeds the capacity of the regulator, over heating of the internal components is likely. The FSM states the rotor windings resistance, voltage snd current limitations. It MAY be possible that your new alternator's rotor specs are at the limit of the regulator's capabilities, causing an over heat condition. In addition, poor grounds, either at the voltage regulator's case or the alternator can cause erratic behavior and possibly high current flow. Any alternator issues, shorted diodes or stator windings do not effect the rotating field components or regulator circuit, only the ultimate capacity of the alternator. Just my opinion of course.
BOB RENTON
 
Question on the field outputs. Does it matter which wire is plugged into each of the field outputs?

Alternator Wires.jpg
 
Looks like poor quality potting compound to me, fully flowing out rather than isolated to locations close to internal conductors/traces that would potentially be experiencing an over current condition, generating heat. Not uncommon to see potting compound flow out like that when exposed to normal under hood temps with cheaply made regs and ECUs. Would expect to see wire insolation damage as well with field circuit overcurrent situation.

On a full floating field alternator, does not matter which field wire is connected to which terminal.
 
I have seen the potting compound "melting" even on new pieces still in box. Most of them on ECUs, but also regulators.
 
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