Topic: Please Help!!! Wiring Mess...Rectifier

[cb750ss]

Hello! I'm definitely a wiring novice! I knew that my bike was overcharging and I was going to replace the old rectifier/regulator with a new Rick's Electric combo unit this morning....until I found that at some point someone has made a mess out of the wiring and I'm not sure what to do???

I have attached photos. The one that really confuses me is the red wire that goes straight from the ignition switch to the old rectifier? I have the old plug that goes to the rectifier unplugged but the rectifier is still hanging there by this 1 red wire that goes straight to the ignition, I know that the new Rick's Combo Unit does not have a place for that ignition wire to go (I think) so I'm afraid to cut that wire and then have issues with the ignition?

Can you help me please!?!<a href="http://" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">http://</a>

[cb750ss]

And my bike is a 76' 750f

[Fritz]

Hello,

your bike indeed looks quite hacked.

Actually the rectifier ist quite simple: It has three yellow "inputs" transferring the AC juice from the alternator and two DC "outputs" (red, yellow) that charge the battery.
Have a look at the schematics in the service manual and you will see that the red wire of the rectifier once was connectect directly to the positive pole of the battery (via the positive secondary pole of the starter solenoid).

Routing the output of the generator through the ignition switch to the battery is a very bad idea, because it will burn the switch contacts when the charge current is quite high, i.e. the battery's charge is low.

How is the regulator that is currently on your bike wired? And please show us your new unit. Maybe we are able to help you wire it up correctly.

Also, a picture of your starter solenoid and fuse box might help.

[cb750ss]

I already took the old regulator off, it just had the white, green, and black wires connected to it, the white wire went to the regulator.

I will take more pictures of everything and the new unit in a few minutes. Thank you!

[Fritz]

I already took the old regulator off, it just had the white, green, and black wires connected to it, the white wire went to the regulator.

That does not make any sense - the white wire is the "output" of the regulator. It should be connected to the field coil.

The regulator wires are:
Black: Ingition, power supply and voltage sense
Green: Ground
White: Drive wire for the generator's field coil

Whenever the voltage measured at the black wire is below the threshold that the regulator is adjusted for, the white wire will be switched through to black. Then there's an intermediate threshold where the white is switched through a resistor to black and the top threshold will completely turn the field coil off.

[cb750ss]

Here are the photos of the new combo unit, the solenoid mounted on a aluminum plate (where everything was mounted), and the original regulator that had the green, white , and black wires going to it. The white wire went straight to the rectifier from the regulator. 

[Fritz]

Does the lighter gauge red wire that connects to the left pole of the solenoid connect to the rectifier (red)?

However, your new regulator/rectifier should be wired as follows:
3 yellow: generator yellow (order does not matter)
red: battery +, left solenoid pole in your photo
black: ignition (black in the wire original harness)
white: field coil (white)
green: both to ground (green in original wire harness or frame)

After wiring it up, make sure your battery is fully charged, connect a voltmeter between the two battery poles and fire the bike up. Rev it up and see that the voltage does not exceed 14.3Volts;

[cb750ss]

that red wire from the starter solenoid also goes up front to the ignition switch I think, I will have to check.

should I just cut that red wire going from the rectifier to the ignition? Also, on the new one the red wire is in the plug that clips in, is that correct?

thanks!

[cb750ss]

It's tempting to just rip it out and start all over....but the thought of that is scary!

[Fritz]

should I just cut that red wire going from the rectifier to the ignition?

Well, i don't know. It all depends on how the PO modified the original wiring. I would download the workshop manual and compare the wiring diagram around the ignition key, rectifier and regulator to your bike. Then I would make decisions.
From here, I can only guess that the PO has thrown out the main fuse and directly wired the  battery to the ignition switch with this red wire. In this case, I would at least splice in  a 15A fuse.

Also, on the new one the red wire is in the plug that clips in, is that correct?

I can't clearly see all wire color on your pic, but there should be a red wire going into the connector. With an original wire harness this should be a direct plug-in but you should carefully check your connectors, they seem to be 'modified' too.