Topic: 75 CB400F regulator/rectifier

[Joel]

I probably didn't have to pull most of the electronics and unmount the battery/filter box to remove the carb rack, but I did.  Here's a picture of the regulator and rectifier that have been mounted on the bike since I bought it.



I'm assuming the box on the left is the voltage regulator and is the original unit.  It was mounted on the left side of the bike with the rest of the electrics.  The box on the right was mounted to a tab on the right side of the bike with the battery.  I'm assuming it is not the original unit but I'm not certain.  The reason I assume it's not original is because the label says it's a combination regulator/rectifier and because it uses two mounting bolts where the tab only had provisions for one bolt.

The label says Shindengen SH230-12.  It has 3 yellow wires, 1 (red?  brown?) wire, 1 black wire and 1 white(w/red stripe?) wire.  I didn't come up with any info on Google other than it seems to have been used on some Kawasaki bikes.

If it is indeed a combination unit, is it less than optimal to have two voltage regulators on the bike?  Could I simply leave the stock regulator off and use the combination unit?

[Bodi]

The Kawasaki alternators were not the same way as ours, this regulator does not supply a field coil output. Someone has just connected it to use as a rectifier. Unusual, but I guess it worked.
I would install a simple rectifier or compatible reg/rect. The later DOHC fours use a reg/rect that can be used although the wiring is a bit different - the field coil is connected to bat + and the regulator terminal whereas with the stock reg in your pic the field is connected to ground and the regulator.

[Joel]

Can you tell me what the white/red wire on the rec/reg is for?  It was connected to the positive battery terminal on my bike.

[Bodi]

Red/white is the output, and should go straight to the battery. Black is ground, I think (Kawasaki colors are unfamiliar to me). The other wire is switched ignition +12V, this powers the regulator section.
Wiring diagrams for bikes using this reg/rect are here http://kz.mbsween.com/manual.html
Possibly if you leave the regulator power sire disconnected it will act like a simple rectifier, I don't know. It's not a good idea to have two different regulators hooked up in my opinion.
The 400 has a barely adequate alternator and messing with the charging circuit like this is not a good idea. The Kawi regulator is for a permanent magnet alternator. The Honda one is an induced field type. In  theory you could skip the Honda regulator by connecting the white wire at the regulator directly to the black wire, giving maximum output all the time. This might overheat the field coil itself, never tried it for a long time personally. If the Kawi regulator is working properly you should get a stable 14.5V at riding RPM with a fully charged battery.
I would still recommend using a rectifier and the stock regulator (if it's working OK). You can make a replacement rectifier quite cheaply using commodity diode bridges, instructions are in these archives.

[Joel]

I figured dual regulators was a waste at least and maybe doing funny things with the electrical. Thanks for the help. I looked up the part number for the stock rectifier and it looks like it was used across the SOHC lineup so maybe I can find one cheap and hook it up.

[Joel]

Since I'm curious and have access to some equipment here at the college, I've decided to try and decipher the function of this combination unit.

If I put a 3-phase AC signal on the yellow wires, how do I simulate a battery on the other two terminals?  Should I apply a 10-15V signal across them?  Should I use a resistor as the load in place of or in combination with the battery?

How does the field coil output function on the stock regulator?  Does it simply cut voltage to the coil when the battery voltage is above a threshold?

[fasturd]

Left is regulator right is the rectifyer. I removed mine after replacing with a modern reg/rec combined unit. Works great.

[Vampire]

I removed mine after replacing with a modern reg/rec combined unit. Works great.

Is this for the CB400F? I purchased a new solid state combined regulator/rectifier from David Silver Spares. It doesn't have a brand but the instruction sheet has a model number RR24. I understand the connections and will have no trouble with that, but the unit is 3"x 3", about twice the size of the original rectifer, and too big to fit in the original position. There is room where the regulator used to be, but I would have to make up mounting brackets.
Did you have the same issues, and where did you fit it?
A photo would be great if not too inconvenient. Thanks.

[Joel]

Those were both mounted on my bike.  I removed the rectifier pictured on the right in the photo and am replacing it with a smaller rectifier I found on eBay after seeing the post on this site about them.  I haven't remounted it yet but it will go on the stock tab under the right side cover.

[Bodi]

The bike should have a simple 3 phase rectifier with three yellow input wires and a red/white output - it grounds through the mounting bolt. The Kawasaki one you have, if it's the one I've played with, has the 3 inputs, a ground, and output. It controls the voltage to 14.5V maximum: I don't know if it dumps extra power to a resistor as heat or if it is smarter and has a switching regulator stage. Both types exist. If it dumps power to a resistor then you may get into a battle between regulators with the Honda one supplying maximum power only to have the Kawasaki one waste it as heat. Personally I would either get a used stock rectifier or use an industrial 3 phase rectifier unit, not common in stores but easily obtainable from Newark or such online sellers.

[Tintop]

I removed mine after replacing with a modern reg/rec combined unit. Works great.

Is this for the CB400F? I purchased a new solid state combined regulator/rectifier from David Silver Spares. It doesn't have a brand but the instruction sheet has a model number RR24. I understand the connections and will have no trouble with that, but the unit is 3"x 3", about twice the size of the original rectifer, and too big to fit in the original position. There is room where the regulator used to be, but I would have to make up mounting brackets.
Did you have the same issues, and where did you fit it?
A photo would be great if not too inconvenient. Thanks.

have been thinking about using this in my cafe build, made by RM Stator in quebec..  here is the link- http://www.rmstator.com/en/motorcycles/honda/cb_550_f_~_k3/regulator_rectifier.htm

[Vampire]

I eventually managed to mount the combined regulator/rectifier where the standard regulator fits. I needed to trim the cooling fins a little, then using eye bolts the new unit fitted nicely, with a minimum clearance from the air box.
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[cb400f/20yo/semi-broke.]

Since your alternator is producing 3 phased alternating current, a constant magnetic field has to be produced via a DC connection.

[Bodi]

If that is a shunt or pass regulator then yes, you will need to connect the field coil directly to power (black switched ignition power wire).
There is some concern about running the field coil at 100% all the time as it will get hot. This is more a concern with larger bikes having more powerful alternators. With shunt type regulators the output power is always at 100%, and the stator coils also get fairly hot.
The 400 has a weak alternator that's probably running flat out all the time anyway. Pass regulators switch the output to maintain a battery voltage, only using the power needed - a shunt type dumps excess power into a resistor. That also wastes engine power of course, but not much... the 400 alternator makes around 150W, around 0.3 horsepower.
I would suggest using a field control regulator, but you did such a nice job mounting that one... so make it work!