Topic: Regulator/Rectifier problem?

[MauiK3]

My K3 had been running fine but recently I came up with an electrical problem.
1973 CB750 K3
New wiring harness, Hondaman fuse block, fresh battery kept on a battery tender.
When I turn on the ignition the dash lights are dim and it won't turn over.
I was able to jump start it and only saw 6 volts at the battery at high RPM, about 3000.
Won't idle at all, likely due to low voltage.
When shut down, the battery shows 12.4 volts connected or disconnected.
I checked the diodes in the modern regulator/rectifier, they check ok.
I checked the stator, it checks ok. No shorts to ground or each other.
I also noticed that with the ignition on and nothing else being done, the regulator rectifier sings just sitting there, it has a whine. That doesn't seem right.
Any ideas?

[SOHC4 Cafe Racer Fan]

Another variable: - what kind of battery are you using?  What type of reg/rec?

Assuming you are using a solid state reg-rec like a Rick's, are you using a lithium-ion battery?  If so, are you using the reg-rec specifically designed (new model 14-100) for use with lithium-ion batteries or the model 10-100?

[MauiK3]

Standard sealed lead acid battery
I got my reg/rect from Yamiya.
I'm going to remove the tank and start backward from the switches to see where I lose half the voltage.
I suppose it may be a burned contact somewhere making a high resistance connection.
The singing rectifier may be a separate thing, I just wonder why it would make such a noise and if it's a problem.