Any alternator experts out there? I need help troubleshooting 10-SI alternator on '70 Corvette.
Problem: No current output when running.
Performed the on car "condition check" per '70 CSM 6Y-18 by grounding the field winding with a screwdriver. Alternator then worked (went from battery only voltage of 10.5v to over 13.5v with headlights on). With this result, CSM says to replace the voltage regulator.
Disassembled alternator, and performed "Voltage Regulator/Brush Lead Clip Check" per '70 Chassis Overhaul Manual 6Y-25. This checks if either brush lead clip is grounded. One lead failed with a low resistance (44 ohm). I then noticed this lead has a resistor attached which is not shown in the Service or Overhaul Manuals (see photos). It goes between brush lead with low ground resistance to a screw which grounds to the case. I removed the resistor, and both brush lead clips passed the test (no ground). The resistor I removed is 44 ohms, so that's what is causing the test to fail.
While at it, I also performed the "Diode Trio Check" (COM 6Y-24). One of the three diodes failed the resistance test.
Should the 44 ohm resistor be installed? The alternator worked for quite awhile with it installed, yet the Overhaul Manual does not show it, and the regulator fails its ground test with it installed.
Is the problem the voltage regulator? Extra resistor? Bad Diode Trio?
Slip Ring End of my 10-SI showing resistor not in chassis manuals:

Photo from COM 6Y-25 with no resistor shown or mentioned in text:
Problem: No current output when running.
Performed the on car "condition check" per '70 CSM 6Y-18 by grounding the field winding with a screwdriver. Alternator then worked (went from battery only voltage of 10.5v to over 13.5v with headlights on). With this result, CSM says to replace the voltage regulator.
Disassembled alternator, and performed "Voltage Regulator/Brush Lead Clip Check" per '70 Chassis Overhaul Manual 6Y-25. This checks if either brush lead clip is grounded. One lead failed with a low resistance (44 ohm). I then noticed this lead has a resistor attached which is not shown in the Service or Overhaul Manuals (see photos). It goes between brush lead with low ground resistance to a screw which grounds to the case. I removed the resistor, and both brush lead clips passed the test (no ground). The resistor I removed is 44 ohms, so that's what is causing the test to fail.
While at it, I also performed the "Diode Trio Check" (COM 6Y-24). One of the three diodes failed the resistance test.
Should the 44 ohm resistor be installed? The alternator worked for quite awhile with it installed, yet the Overhaul Manual does not show it, and the regulator fails its ground test with it installed.
Is the problem the voltage regulator? Extra resistor? Bad Diode Trio?
Slip Ring End of my 10-SI showing resistor not in chassis manuals:
Photo from COM 6Y-25 with no resistor shown or mentioned in text:
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