Author Topic: Regulator/Rectifier Compatibility (Read 3635 times)

thechris · « **on:** January 29, 2007, 08:22:40 AM »

Hello All,
I'm new to this site, but have done a little bit of looking around. I've seen that there is a great wealth of knowledge here and perhaps someone could help me.

I have a 72 CB750 and I just bought a Reg/Rec from Ebay for a 80 CB750 thinking they were pretty much universal. After reading some posts on here, I see that they are indeed NOT universal because of different charging systems. Luckily, I haven't installed this yet, but would this Reg/Rec work on a 72? I'm guessing not, but it never hurts to ask.

Thanks for any help.

Clutch Cargo · « **Reply #1 on:** January 29, 2007, 08:47:26 AM »

I believe that the 1980 unit is solid state - not at all compatable with your 1972 CB750.

Go here for new rectifiers and regulartors for your 1972 750:

http://www.oregonmotorcycleparts.com/rectifiers3p.html

Mike

TwoTired · « **Reply #2 on:** January 29, 2007, 09:26:54 AM »

If I had solid information about how the 80 CB750 charging system worked or was wired, I could make a fairly good guesstimate if it could be used on the 72 750. An 80 wire diagram would suffice. You'll probably need that to figure out the color codes for correct interconnection anyway.

Solid state is not a key issue, BTW. It's the alternator wiring configuration that IS.

The 72 has a solid state rectifier and mechanical regulator. But the OregonMCparts, replacement unit is all solid state. They will both work.

Cheers,

Pinhead · « **Reply #3 on:** January 29, 2007, 10:22:51 AM »

The '80 750 has the same charging system as the '79 CB650. The only difference between the later models and the early models is the field coil. In the '80s models the field coil is the rotor that spins on the end of the crankshaft. On the mid '70s models the field coil is stationary with the soft iron rotor spinning between it and the stator.

There's only two differences between the '80s model reg/rect and the older one: the later one is one unit while the older one is two, and the later one is solid state. They're both a three-phase system.

The regulator/rectifier in my sig would work on your charging system.

crazypj · « **Reply #4 on:** January 29, 2007, 10:34:54 AM »

It will work fine but you have to connect it correctly.
3 Yellow ( maybe white?) to the alternator yellows, red to battery, black to switched power source (control voltage)
Green to ground and the remaining two wires (a white, and a black) to the field coil.
Will also work with CB 400, 500 and 550
PJ

medic09 · « **Reply #5 on:** January 29, 2007, 11:11:10 AM »

So, if you're minimally mechanically/electrically inclined, you can make it work and folks here will talk you through it (someone will). If, like me, you're not or you want new components because the old ones were fried, the link to Oregon Motorcycle Parts is the place. I think it's likely to be about $45/piece for each component. Tony Weeks, the owner of Oregon Motorcycle Parts is a good guy and will email you as much as you need to get it right.

Either way, you're good to go.

thechris · « **Reply #6 on:** January 30, 2007, 05:02:31 AM »

I think I'm a little confused. So, the Reg/Rec will work as long as it is hooked up correctly? Just that the wiring will be different from stock. Is this right?

If thats the case, I can live with that. This whole bike is one big mess at the moment. I bought it from a guy who obviously didn't know what he was doing. Right now there is a single unit Reg/Rec, but the Regulator part of it doesn't work. So this guy left the single unit and connected up a separate regulator instead of getting a new part. I guess the function is the same, but it makes for a mess with extra wires. I'd really like to clean that up.

TwoTired · « **Reply #7 on:** January 30, 2007, 09:12:37 AM »

Quote

I bought it from a guy who obviously didn't know what he was doing.

Or, maybe he did and you just don't understand it?

Why don't you post the colors of the wires on the unit you want to use? If you give us some solid information, we might be able to give you a solid direction to take.

Or, you could just use crazypj's helpfull information.

What is the real issue you are trying to solve? Do you have charging issues? Or, simply a rats nest of wires that is indimidating you?

Have you checked out the FAQ? Can you use, or do you own a multimeter?

Cheers,

thechris · « **Reply #8 on:** January 31, 2007, 04:46:46 AM »

It's mostly the mess of wires.
I've got a wiring schematic to the 80 CB750 and as long as I can see where the wires need to go, I should be ok. My real concern was the compatibility issue.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #9 on:** January 31, 2007, 10:21:09 AM »

Quote from: thechris on January 31, 2007, 04:46:46 AM

It's mostly the mess of wires.
I've got a wiring schematic to the 80 CB750 and as long as I can see where the wires need to go, I should be ok. My real concern was the compatibility issue.

Not to stick my nose in (which I guess I just did) but I'm following this due to a project bike also and want to see a good resolution. Don't let the mess of wires intimidate you. Two Tired and PJ (and Pinhead too) are your best resources! I don't think I can compare to these guys with their expertise but it's really not that complicated. You have to take a logical stepped approach to this. You can either clean up and remove all the rigged wiring, remove the bastardized Reg/Rect unit and go back to stock or let us know what color wires the '80 unit has since they do not have your unit in hand to see. In all likelihood you might be able to take the '80 unit and attach your old connector and it will work IF the wires are hooked up correctly by knowing the colors.

Pinhead · « **Reply #10 on:** January 31, 2007, 11:48:33 AM »

In the '80 reg/rec you should have two wire connectors: one with 5 wires and the other with 3 wires.

In the connector with 5 wires, there should be three yellow wires and two "other color" wires. The two other wires go to the field coil/rotor and the three yellow's go to your stator (3-phase output).

I don't remember the coloring in the other connector (with the 3 wires) but it's easy to check to see what they are. One of them is ground (test with the multimeter for voltage to ground, should be 0v) one of them goes straight to the battery (check for ~12v with the ignition off) and the last wire is the "ignition" which will only be "Hot" with the key on.

hymodyne · « **Reply #11 on:** January 31, 2007, 05:30:11 PM »

This has been a helpful thread. I'm planning to install a one piece unit later this winter.

as for the wires in the bucket, I printed off the pages for the 550 and the 500K and sat in front of the nest until it made sense and the connections were proper.

I just completed my Ph.D in literature earlier this week. I'm planning on riding my Honda down from MA to NYC for graduation in May.

Hym

medic09 · « **Reply #12 on:** January 31, 2007, 05:39:59 PM »

Congratulations! Nice way to get to graduation. Hang out in the wings, then ride it up on stage when they call your name...

Bob Wessner · « **Reply #13 on:** January 31, 2007, 05:48:49 PM »

Quote

I just completed my Ph.D in literature earlier this week.

Congratulations.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #14 on:** January 31, 2007, 05:51:51 PM »

Congrats Dr Hym. How does that sound? Was the doctorate in lit from reading the wiring schematics?

medic09 · « **Reply #15 on:** January 31, 2007, 05:54:06 PM »

He wrote a brilliant thesis comparing the terse language of the wiring diagram to the slightly more illustrative prose of mechanical drawings. The committee said it was brilliantly crafted, but sparse in it's verbiage.

hymodyne · « **Reply #16 on:** February 01, 2007, 03:44:23 AM »

thechris · « **Reply #17 on:** February 01, 2007, 05:11:12 AM »

Pinhead- there are two connectors and your decscription sounds right. I'm at work now and don't have the unit in front of me so I'm not 100% sure.
The connectors are all going to have to be removed. My bike doesn't have any on it as of right now. It was stripped of those before I bought it. Just a matter of tracing wires.

Hymodyne- Congrats!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #18 on:** February 01, 2007, 11:39:44 AM »

VintageConnections.com

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Author Topic: Regulator/Rectifier Compatibility (Read 3635 times)

thechris

thechris

thechris

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