Topic: testing oem regulator and rectifier

[kawabunga]

I've done the searches and cannot seem to find a simple, spelled out, how to test a rectifier and regulator write-up. What is the proper way to do it? The settings, orientation of the leads, etc...

I'm working on a '75 550F. OEM stator, field coil, rectifier and regulator.

I'm dealing with a charging issue that I initially believed to be my stator, so I sent it off to Rick's. They told me the stator bench tested fine and suggested I test a few other items before moving forward with a rewind. I have a Gardner Bender GDT-3190 digital multimeter. It's nothing fancy, but it has most of the basic functions. Can I accurately test the rectifier and regulator with this multimeter?
https://www.gardnerbender.com/en/p/GDT-3190/Gardner-Bender-GDT-3190-Digital

I tested the field coil. Multimeter set to 200 ohms, leads to green and white wires. It measured at 4.6 and no grounding issues.

When I tested the rectifier, I had the multimeter set to 200K ohms, black lead to the red/white wire, red lead to the yellow wires. They measured 86.3, 87.5, 87.9. When I switched the leads around, no measurement was displayed.
I then put the red lead to the green white and the black lead to the yellow wires. They measured 85.3, 83.6, 83.8. When I reversed the leads, again, no measurement displayed.
Am I doing this correctly?

For testing the regulator, I had the multimeter set to 200 ohms. With all the regulator wires disconnected, one lead on the black wire tab and the other on the white wire tab. It measured 0. I disconnected the battery negative terminal, put one lead on the black wire that goes to the regulator and the other lead to the battery ground wire. It measured .3.
Am I doing this correctly?

Any guidance with how to properly test these items is greatly appreciated. Thank you.

[Bodi]

The OEM electromechanical regulator is difficult to test but they rarely fail. If you open the case, you'll see what looks like a relay. The relay coil and return spring are balanced to pull in at around 13V. Your Ohms measurement is correct (within the meter's accuracy at very low resistance) the regulator senses system voltage and, with the voltage low - ie no voltage at all as when you measure it - it closes its upper contact to pass full system voltage to the field coil. Somewhere around 13V it opens that contact  but does not fully move the armature to touch the lower contact and the field coil is powered through the resistor (visible on the back side of the regulator), so alternator output is reduced quite a bit but it still makes power. Over some voltage (14.5V?) the armature pulls in fully and the lower contact is closed, connecting the field coil input to ground and the alternator makes zero power.
In actual operation with engine running and a fully charged battery, the relay switches quite often between full/part/no alternator output. It tries to keep the system voltage at around 14.5V.
There are adjustments but I recommend that you do not fiddle with them. You need test equipment you don't have to make correct adjustments and screwing it up will either have your battery always discharging as you ride, or overcharging and eventually "boiling" off the electrolyte. (it's actually reducing the water to hydrogen and oxygen, but the result - a bubbling battery and disappearing electrolyte - is usually called "boiling").
Note that the regulator measures voltage on the black wire, that wire can be well below the actual battery voltage if the electrical components like fuses, switches, and bullet connections are corroded or otherwise have a higher than normal resistance. If you have overcharging problems check the regulator black wire voltage to the battery positive terminal, with engine running and all normal loads (headlight etc) on. Over 1/2 Volt should be worrying. If it's 2 volts, the regulator will be trying to get the battery up to 16.5V which will cause battery electrolyte level to drop.
The rectifier is pretty easy to test with your meter but a meter with "diode test" function is preferred.
There are 6 diodes in it in pairs, with a pair connected to each yellow wire: one "points" to the positive output, the other one points to the yellow wire from the negative output. When a yellow wire's voltage from the stator is above the positive terminal's voltage, current flows to there. When it's below the negative terminal's voltage, current flows there.
So to test: connect either meter probe to the red positive output. Measure resistance (lowest range) to each of the 3 yellows. The reading should either be high or low (it doesn't matter, really, and meters are not too consistent with which lead is positive in resistance mode) but all three measurements must be close to the same. Switch the probes so the other one is on positive. Measure to each of the three yellows again. Whatever the first set of readings were, these must be the opposite: high one way, low the other way.
Repeat with the meter probe on the black negative output.
If you were making your own rectifier from diodes, you would need to verify that the diodes are the right way around... but Honda would not get that wrong so if the readings are OK when tested, then the rectifier is OK.
If any readings are weird you have a problem. A single high reading when you expect a low reading means a diode has failed "open" - nothing terrible will happen but you will have reduced alternator output to the system. If you read low from any yellow wire to either output in both directions, a diode has failed "short" and you risk melting rectifier wires.

[kawabunga]

Bodi, thank you for the detailed response!

I realized I did not specify my actual charging issue... I'm not getting enough charging. The last ride of last season (I'm in MN) the battery was dead after about 85 miles of riding with frequent stops. I did a voltage test on the battery with the bike running and it was low. I don't have in my notes what the voltage was, unfortunately. I believed it to be the stator so I sent it to Rick's, so I cannot do any further testing with the bike running until I get that back.

I let my battery sit off the tender all night and checked it this afternoon and it measured 12.8v, nice to know my battery is fine.

So, it sounds like my regulator is okay then? Or should I actually open it up and do some testing?

Do my readings of the rectifier sound correct to you as I have reported them in my first post? Or is the diode test what really needs to happen?
I believe there is a multimeter at work that I could use that probably has a diode tester, I will check next I go in.

[Bodi]

Yes your measurements of the rectifier indicate that it's OK.
A resistance measurement is an OK basic diode test, almost always. The diode test function in a digital meter puts a few volts across the test leads through a resistor, the reading is in volts. Most Honda rectifier diodes have a forward voltage drop around 0.6V, so the reading is generally 0.5 to 0.6. Connected "reverse" where the diode blocks current flow, the diode test usually reads "error" or similar... different meters display this in different ways.

[scottly]

With the key on, engine not running, what voltage do you measure at the white regulator terminal?

[kawabunga]

With the key on, engine not running, what voltage do you measure at the white regulator terminal?

Red lead on white terminal, black to battery negative, it settled at 10.35v.
I don’t have the stator in the bike, so it and the field coil were not hooked up.

[scottly]

With the key on, engine not running, what voltage do you measure at the white regulator terminal?

Red lead on white terminal, black to battery negative, it settled at 10.35v.
I don’t have the stator in the bike, so it and the field coil were not hooked up.

Without the field hooked up, there should be a higher voltage. What do you measure across the battery terminals? With the positive meter lead connected to the battery positive terminal, what voltage do you read with the negative meter lead on the black reg terminal, key on, engine not running?

[kawabunga]

Red lead on white terminal, black to battery negative, it settled at 10.35v.
I don’t have the stator in the bike, so it and the field coil were not hooked up.

Without the field hooked up, there should be a higher voltage. What do you measure across the battery terminals? With the positive meter lead connected to the battery positive terminal, what voltage do you read with the negative meter lead on the black reg terminal, key on, engine not running?

The battery has been off the tender for over two days now and it measures 12.80v.
Red lead on battery positive, black lead on regulator black wire terminal, key on, it measures 1.41v.

[bryanj]

Thats too much of a volt drop, you need to check the voltage at verious points from battery +ve onwards e.g.solenoid, red at ign switch, black at ign switch with key on, black in headlamp.

Somewhere is a poor connection and you need to find it or the charging system will never work properly.

[kawabunga]

I’ll dig into that and report back.

So, to those looking at my readings, my field coil, rectifier and regulator. Do those readings look suitable for use?

Rick’s says my stator is fine by their standards. If all four of these components test to be in working order, what is the next most likely culprit for a poor charging system?

[bryanj]

Bad connections are 99% of all charging problems

[kawabunga]

Thats too much of a volt drop, you need to check the voltage at verious points from battery +ve onwards e.g.solenoid, red at ign switch, black at ign switch with key on, black in headlamp.

Somewhere is a poor connection and you need to find it or the charging system will never work properly.

Without the field hooked up, there should be a higher voltage. What do you measure across the battery terminals? With the positive meter lead connected to the battery positive terminal, what voltage do you read with the negative meter lead on the black reg terminal, key on, engine not running?

What is the ideal voltage I should be seeing at the white terminal of the regulator?

(No stator or field coil hooked up.)

[bryanj]

Same as on black lead

[kawabunga]

Same as on black lead

That confuses me...

When I performed this test:

With the key on, engine not running, what voltage do you measure at the white regulator terminal?

Red lead on white terminal, black to battery negative, it settled at 10.35v.
I don’t have the stator in the bike, so it and the field coil were not hooked up.

You both responded that 10.35v is too low. What should it be?

[bryanj]

Black and white lead to ground should both be same as battery voltage

[kawabunga]

Black and white lead to ground should both be same as battery voltage

Gotcha. Thanks for clarifying.

I’m working on it right now. What is directly upstream of the regulator that could impede voltage? So far most things are looking good.

[kawabunga]

I just spent the afternoon going through every bit of wiring I could find. Disconnected, cleaned, and put a dab of dielectric grease on all multi-wire plugs. Some had some light corrosion accumulating but they were pretty clean for the most part.
I disassembled the ignition switch and kill-switch, those contact points were dirty and full of old grease and dust. I cleaned them up and put just a touch of dielectric grease on them.
I opened up the regulator, it looked basically brand new inside. Regardless, I ran a piece of light emery cloth between the contact points that were touching and cleaned it out well afterwards.
I checked the voltage at the regulator after performing each check and clean. No change on the voltage at the white or black terminal, it still settles around 10.35-10.45v.
The only thing that made a difference to the voltage measurement was pulling the headlight and taillight fuses (or unplugging the lights). After that it would bring the voltage up to around 11.5v.
All of the lighting is OEM.
Nearly everything electrical is stock on the bike, with the exception of a Dynatek electronic ignition and Dynatek coils.
One other thing I noticed, in my Haynes manual, while reading the wiring diagram I noticed it calls out a "pointless regulator". There's definitely points in my regulator.
I'm struggling to figure out what exactly is upstream of the regulator that may be causing a drop in voltage. Or perhaps my regulator is just working properly anymore?
I'm running out of ideas on what to check... Are there any test I can perform internally on the regulator to see if it's working properly?
Thanks.

[kawabunga]

I was looking over a few things and noticed that the main fuse on my fuse block was looking droopy, like it had melted and sank down in the housing a bit. After having the key on for less than 30 seconds, the fuse was too hot to touch.
I fashioned up a test fuse block, using jumper wires with automotive style blade fuses and tested things again.
With the bike on, the fuse no longer gets too hot to touch.
Also, the voltage measurements at the black and white terminals of the regulator went up a little. From 10.35v with the OEM/melted fuse block to 10.90v with my test fuse block.  (all lights on, like before) That doesn't bring me up to battery voltage, but that's a solid half volt. Is that bringing me back up to acceptable use range? Or are there other things that should be looked at?
See my previous post for my testing and findings earlier in the day.

[scottly]

With a load on the battery, the voltage will go down over time. When trouble-shooting a voltage drop, sometimes it's easier to make all your measurements with the meter red lead on the battery positive. Look for a voltage drop at the black regulator wire of less than 1 volt. If the main fuse is getting hot, it has high resistance in the connections, and is a smoking gun. (pun intended)   

[bryanj]

With Dyna ignition the generator will not charge until you are in the 6000 ish rev range, these systems are power hungry and its not a big generator

[kawabunga]

With a load on the battery, the voltage will go down over time. When trouble-shooting a voltage drop, sometimes it's easier to make all your measurements with the meter red lead on the battery positive. Look for a voltage drop at the black regulator wire of less than 1 volt. If the main fuse is getting hot, it has high resistance in the connections, and is a smoking gun. (pun intended)

Testing with red lead on battery positive and black lead on white and black regulator terminals measures 1.20v. That is with my new test fuse block which no longer gets hot. I will be getting a new terminal and use mechanical circuit breakers rather than glass tube fuses.

With Dyna ignition the generator will not charge until you are in the 6000 ish rev range, these systems are power hungry and its not a big generator

So what is a guy to do then?

I currently have the Dynatek electronic ignition kit from 4into1 (which states Magna coils with 5 ohm primary resitance) with a Dynatek Dyna S ignition system installed. I was having serious issues with accurately timing my ignition with the points plate that was in there, it was inconsistent and changed with the screws being tightened, perhaps it was a bent/warped plate. I've timed a lot of points bikes without issues, but this one caused me a lot of grief over the years, which is why I went with the electronic ignition, as well as all the other reasons one does.

[bryanj]

That volt drop is too high work from battery along loom with black probe. First turn kill switch off and disconnect headlight and tail light
Start at battery lead on solenoid
Input of fuse
Output of fuse
Ignition switch red
Turn ign on
Ignition switch black
Multi black in headlamp.

Somewhere you will find that volt drop and the problem is between that point and previous test point.

Come back with results/questions.

As to dyna you are going to have to ride harder in lower gears!!

[scottly]

With a load on the battery, the voltage will go down over time. When trouble-shooting a voltage drop, sometimes it's easier to make all your measurements with the meter red lead on the battery positive. Look for a voltage drop at the black regulator wire of less than 1 volt. If the main fuse is getting hot, it has high resistance in the connections, and is a smoking gun. (pun intended)

Testing with red lead on battery positive and black lead on white and black regulator terminals measures 1.20v. That is with my new test fuse block which no longer gets hot. I will be getting a new terminal and use mechanical circuit breakers rather than glass tube fuses.

1.20 volts isn't horrible, and I don't know what you mean by a "new terminal and mechanical circuit breakers"?
What exactly are your symptoms with the engine running, as in voltage readings across the battery terminals?

[kawabunga]

1.20 volts isn't horrible, and I don't know what you mean by a "new terminal and mechanical circuit breakers"?
What exactly are your symptoms with the engine running, as in voltage readings across the battery terminals?

I found a different style of fuse block that accepts circuit breakers, so it’s not really a fuse panel, so I called it a terminal. The big bonus is that you don’t have to replace blown fuses. Once you remedy the issue you just reset the circuit breaker, just like the circuit breakers in a home. Sorry for the confusion.

I don’t have the stator in hand to test the running output the moment. It’s currently at Rick’s Motorsport for what I thought was going to be a rewind as I was under the impression that my stator was failing. (Battery was dead after a long ride late last season and it tested at the battery terminals running with very low voltage, 12.5-12.6v around 4-5k-ish rpm - I found a video of testing it last fall) Turns out it bench tested fine at their facility so I’ll have them mail it back to me so I can do further testing. In the meantime, I’ll keep searching for lost power in old wiring.

I wasn’t aware that my Dyna S ignition and Magna coils would eat up so much extra voltage. Long story short, I was chasing a timing issue and decided to upgrade that system. After your guys’ input and doing more digging, apparently the CB550 charging system wasn’t anything stellar to begin with, and swapping to electronic ignition and high output coils would further tax the system. So if there are underlying issues robbing the system of what little excess power there was to charge the battery, putting the new ignition system components on exasperated that issue. I have found one for sure so far with the melted fuse block. I’m hoping to free up a little more power yet. Probably going to try converting the lighting to LED as well. I don’t like any modern LED headlights though, I prefer the classic look of the original but if it helps prevent killing the battery every ride I might have to bite the bullet. I don’t want to go back to points so I have to find other options.

Any suggestions would be greatly appreciated.

[bryanj]

Think of it this way
1.2 volts is 10% of battery voltage
That means you only get 90% of possible magnetic field
So only 90% of possible charging output.

As stated chatging on these is marginal so nuff said!