Topic: CB400F charging issues using M-Unit **sort of fixed**

[Dave87]

Can't remember the exact Voltage we got from the White but it was pretty solid.
How we achieved it was by connecting the Red and Black to the +iv and the Green to the -ive of a car battery that read about 13.something volts. We then checked the voltage output of the White with a multimeter. We found that the White was now active. As it was not installed in the bike and had no working Alternator we figured there was no point testing the Yellows during this test.

It may have been a bit agricultural but we were running out of ideas.

[Bodi]

This keeps going in circles.
The alternator makes power from the field coil electromagnetic field. Voltage on white means pretty much nothing, the coil has to pass current... is the other field coil wire grounded? Are you sure your R/R works (like the OEM regulator) by controlling the positive? Some (ie DOHC4 type) control the negative and want the other field wire at +12V.
If unable to measure field coil current, you should be able to tell the coil is working by holding a steel tool near the alternator cover, it will be attracted by the magnetic field when the coil is working.
If that coil is making magnetic field, a spinning rotor will induce voltage on the stator yellow wires. Disconnected, I think over 25V should be expected yellow-yellow (all three combinations )but I've never measured it.
So measure the field current or test for the magnetism with a screwdriver or something.
The alternator must be fully assembled - field and stator coils on the cover, mounted over the rotor - to make power. If you have a good field, the rotor is turning, and all the wires are connected... it doesn't have many ways NOT to work.

[Dave87]

Thanks Bodi for entering the discussion!

Not sure exactly how this aftermarket R/R works but it is meant to be a direct replacement.

The other field coil wire goes to earth.

Interesting to hear about the current. I'll have to test that over the weekend and let you know. Thanks for that tip!

[calj737]

This keeps going in circles.
The alternator makes power from the field coil electromagnetic field. Voltage on white means pretty much nothing, the coil has to pass current... is the other field coil wire grounded? Are you sure your R/R works (like the OEM regulator) by controlling the positive? Some (ie DOHC4 type) control the negative and want the other field wire at +12V.
If unable to measure field coil current, you should be able to tell the coil is working by holding a steel tool near the alternator cover, it will be attracted by the magnetic field when the coil is working.
If that coil is making magnetic field, a spinning rotor will induce voltage on the stator yellow wires. Disconnected, I think over 25V should be expected yellow-yellow (all three combinations )but I've never measured it.
So measure the field current or test for the magnetism with a screwdriver or something.
The alternator must be fully assembled - field and stator coils on the cover, mounted over the rotor - to make power. If you have a good field, the rotor is turning, and all the wires are connected... it doesn't have many ways NOT to work.

I believe the AC voltage on the 3 yellows should all be over 50v if healthy. On most 550s and 750s I've tested they have been in the 70v range.

[Dave87]

G'day all, 
Sorry for the lack of activity, have been rather occupied with moving etc.
I am very happy to report that my charging issue is fixed!
The culprit... The Regulator/Rectifier body was earthing to the frame. I have seen a lot of people having similar issues to me with new R/Rs so the first thing I will recommend is make sure the body is isolated! I would have saved myself a lot of time and heartache if I had known that they needed to be installed like thus.

I have added the wiring diagram I used which is correct and working. Sorry for the lack of colour etc. Yes the black from the R/R goes to the AUX of the M-unit.

Thanks a heap everyone!

[scottly]

The body of the reg/rect shouldn't have to be isolated from the frame??

[Dave87]

Not sure Scotty,  this was a Forsetti direct replacement. Not sure if they are all the same but that's what's worked. It was earthed out and not working. Now it is not and it is working.  I won't argue with that. Haha.

[scottly]

With the key on, engine not running, measure the voltage between the reg/rect case and earth.

[vortexuk]

I am having the same problem but not with m unit. Complete rewire of bike, including upgrade to combined reg/rec, I have wired red to battery positive (has power) black to power when switched on (has power) green to earth, but when the bike is on no power to white field coil wire? i have tried 3 reg/rec with no joy. Battery i am using is lithium ion, could this be the reason?

Also i have tried wiring field coil direct to power and it energises. I am at a loss to work out what the problem is

[Dave87]

I'm sure others will have more to say on this but I'll give you my 2 cents worth in case it helps.
It seems you have it wired correctly and I highly doubt that you have a problem with the battery.
I would hazard a guess that the culprit is something to do with the earthing.
In the end I went with a 'Ricks motorsport' R/R. It has 2 earth wires instead of the just the one. Since installing this it worked great!
I feel that with some of the generic models (I found the same cheap unit sold by a few different brands) like the first 2 I tried with just a single combined earth that the signal coil signal gets lost somewhere in the unit's circuitry.
My recommendation is if you haven't already try a 'Ricks. As annoying as it is I think you'll have the issue fixed.
If not I have no idea where to go. Sorry mate.