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Total newb here and I'm trying to learn more and work through bike problems. I have a 1970 CB350 that I recently purchased and have been working on. When tuning the carbs and then riding the bike the 12v Shorai has been drained too low to use the electronic ignition so I brought it in to get charged and I'm confident there is an issue with the charging system on the bike. I wanted to test my rectifier with my multi meter and got into today and this is what I'm assuming my rectifier is:

unnamed.jpg

Assuming thats correct when I unplug the harness the plug is female on the rectifier side. I have not seen this before or during any of my research.

unnamed-1.jpg

If this is normal, how can I test the Rectifier? Is it clear that judging by this something weird has been done with the wiring all together?

Side note: could a low charge on the battery make the bike run weird? I noticed that this might be the case when I was riding around the block after I realized the battery was getting drained. Next, check will be the points.

Thanks for your help, stoked to work through this one and learn some electrical stuff!
 

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That is a Kohler Chinese Clone regulator/rectifier. It uses three wires plus ground the case. The center tap on the reg/rect is 12VDC regulated. It goes to the battery. The outer 2 tabs are for the output of the alternator.

Final assembly of reg.jpg

I used the original rectifier plug. Pink is from the alternator...Yellow is from the alternator, Black is 12V Battery Voltage, Green is ground. The case needs to be grounded on these. A good ground. I ran a second ground wire from the mount bolt to the frame for extra goodness.

The four prong female plug plugs into the harness (assuming you have stock harness) were the original rectifier was plugged in....if you have a different connection, the wire colors should be the same though.
 

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Discussion Starter #3
Thats exactly what I'm looking at. How do you test that then?

Also, if i were to buy a new rectifier it would be male on the rectifier side right? That means I need to wire a different harness on the non-rectifier side in order to make that female right? In other words, this isn't the stock wiring setup.
 

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The rectifier plug on a stock rectifier is female...the harness male....But you have a pic of the rectifier/regulator....you will need to wire it yourself anyway..... you can just wire it up the way you want.
 

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Check out Sparckmoto.com. Common-motor (A site sponsor) has them too. They are prewired for our bikes, work well (I know, I replaced my kohler clone with it and helped MAtt at Sparckmoto test them)

Matt at Sparckmoto or Brendan at Common Motor also will lend a lot of assistance if you have any issues. They support our bikes and sites and even if they weren't a bargain, they are worth supporting....
 

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Discussion Starter #8
Thanks for the suggestions, I will look into it. But I'm still curious if/how I can test the Kohler with my multimeter?
 

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Thanks for the suggestions, I will look into it. But I'm still curious if/how I can test the Kohler with my multimeter?
You really can't....Open and shorted, shorted to ground can be tested. If you really want to test, you need a variac (Adjustable AC transformer, hooked it to a battery....Adjust AC until starts grounding AC....

That's a lot of work for a $20 item....

Because the regulator and rectifier are combined internally, there is no exact test...If you monitor AC on the input,, and DC on the output, you can pretty much verify operation while on the bike.....

Bench testing by resistance only is futile...
 

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A quick check for a one piece rectifier/regulator like a Kohler is at
... Hope this helps a bit more... Use a voltmeter instead of the fancy B&G tester...
 

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A voltmeter alone doesn't test it like that box. That box is putting in AC, checking the DC out, and checks impedance through the device. While I can check this with the tools I have, not many people have them...
 

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Yes, perhaps I have oversimplified, using that semi-sophisticated tester to demonstrate a path to try. I was thinking of substituting a 16 volt doorbell transformer to supply the AC, then just use a DC voltmeter to check the DC output for a simple test, nothing really technically demanding. If the OP is not comfortable around electrical stuff, best to leave it to someone who is...
 

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But the actual in our bikes generate as high as 60v AC. The regulator does nothing until the DC exceeds 15 volts or so. So to test, you need to provide AC volts and a monitored DC load. Increase the AC until the loaded DC exceeds 15v and stays there, indicating the screen circuit is working properly. The problem with the 3 terminal reg/rect is that the caps and resistors in the circuit make it hard to read the rectifier alone...

The tester probably supplies 60v ac to the 2 ac lines and then sees the loaded DC line does not exceed 15 volts. Under 13volts would be low, over 15.5 volts would be high, 0 or ac volts on the DC side would be shorted...
 

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OK, I'm interested now, I've got one of those Kohler regulators, an oscilloscope, a variac autotransformer and I'll try to round up a camera to shoot some video of the process. I never ever thought about testing one of these things (other than replacement) but perhaps it is time to do it and document it. I'll try to do it within the next few days, any suggestions are welcome...
 

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Discussion Starter #15
I'll check out that video.

Another thing that I do find a bit confusing is that black wire with the blue around it that you see in the first photo. The person I bought it from had that wire running from where you see it bolted to the negative on the battery...what purpose does this serve?
 

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I'll check out that video.

Another thing that I do find a bit confusing is that black wire with the blue around it that you see in the first photo. The person I bought it from had that wire running from where you see it bolted to the negative on the battery...what purpose does this serve?
That appears to be the ground wire, that person was likely just making absolutely sure that the case of the regulator was grounded to the negative battery terminal,,,
 

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Discussion Starter #17
I'm going to go to a place here in San Francisco at the end of the month where I can work on it with a mechanic so that I learn along the way and do it the right way as well....I'll keep you posted on what he/she seems to think and what/how we run the tests.

I don't really know where to start with testing things as I've never done any electrical stuff.
 

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I agree with ENB54 on it being a good ground wire. I did that to mine, but used the correct Honda color for ground which is green. On Honda's, Black is always +12V, not ground. This often is confused because most cars use Red for +12V and Black for -12V (GND).
 

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Well all, FYI... There is a bit more to these Kohler type rectifier/regulators than I thought, but maybe just my particular AKH6003 knockoff. Firstly, they must have a 12 volt battery connected to the B+ and the case (Negative terminal) otherwise very strange readings and voltages which make little sense are encountered. Once I attached a decent 12 volt battery and a load, I found that as soon as you apply an AC voltage, the diode bridge conducts, and once the output voltage exceeds battery voltage the system will be in the charge mode until (in my case) the cutoff of 14.6 -14.7 Volts DC is reached, then the R/R conducts the excess to the device ground. During charging and regulating the Kohler device gets very hot, at least when using the variac and 60 cycle power, I think I’d advise to use a motorcycle stator assembly to generate AC into the R/R for testing purposes. I did not shoot a video because there are several on YouTube already, but am attaching a couple of photos showing the general setup using the variac, voltmeter, device under test (R/R), 12V battery, portable laptop oscilloscope and a piece of amateur radio equipment for the load. I used the amateur radio for the load because I wanted to see if you could hear any of the 60 cycle (or harmonics) power hum from the variac through the audio section of the radio (apparently you can). I also learned that you cannot have your laptop/oscilloscope connected to the AC supply because the variac ground is floating (smoked one probe assembly) and at a differential from regular AC ground. I also learned that when the DC starts charging the battery, the AC can be as little as about 15 volts according to my old Digital Multi Meter (DMM). Hope this helps a bit more, but as others have said, this is not a test technique for the average person…

IMG_0482_1.JPG IMG_0483_1.JPG

You know, after thinking about this test and results, I'm starting to believe that there is something odd about this, will look harder when I get back home next month (vacation time for a few weeks...)
 

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Here's what I believe those regulators have as circuitry:

regulator2small.jpg

Since we only have access to 4 points, all external, we really would have issues trying to diagnose this type with only a voltmeter.

Even the basis Honda regul;atopr is hard to diagnose. The rectifier is easy, but the regulator is not a simple circuit either.

CB350-CB360 Regulator Schematic.jpg
While you can check for shorting, open circuit doesn't reveal a problem necessarily either, as until the regulator activates the SCR, you have an essentially open circuit too.
 
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