Should the Regulator be too Hot to Touch?

[xjwmx]

I never said anything about the battery. I don't know what you're measuring, but you're not measuring the resistor. Yes, both resistors "measuring" the same means something. It means you're reading something besides the resistor. Could mean the meter is broken or not set up right.

 

[freddy3]

I'm sorry, I must've misunderstood your last reply.
If you look at the photo in my original post, I'm measuring the resistor with the meter's positive lead at one pole and the negative lead at the other. I'm not sure how else to measure a it? Unless you're talking about unsoldering the resister from the regulator first and then measuring it?
In the meantime, I'll check the DVM's battery, but it's a pretty accurate meter (Fluke).

 

[retiredgentleman]

freddy3;

I think your problem with the hot resistor may lie with the rotor. I suspect the resistor is there to give a minimum series resistance when the contacts for the regulator are open. I'm going to guess the resistor is about 5 ohms.

The rotor normally draws about 2 amps. Lets assume half the current goes through contacts and half goes through the resistor. That means the resistor normally has about 1 amp of current flow. Power dissipated in the resistor would be 1 x 5 = 5 watts.

Now what happens if the rotor winding is partially shorted out, and draws 4 amps. The resistor again gets half or 2 amps. Power dissipated in the resistor would be 4 x 5 = 20 watts (2 amps squared is 4).

So if 5 watts is warm, then 20 watts is hot

So , remove your brushes and measure the rotor resistance. I'm thinking you will find it much less than 5 ohms due to the partially shorted out winding.

When you saw the voltage vary from 13 volts to 15 volts, the rotor winding was partially shorting out and then returning to normal, and then repeating the same cycle.............magnetic field strength varing from normal to perhaps half normal.

I see a rewound rotor in your future.

 

[freddy3]

Boy, I hope it's not the rotor. I replaced that several years ago and it was an expensive bitch (and likely even more expensive now!). Do you want me to measure the resistance between the two slip rings and/or between the slip rings and the core?

 

[retiredgentleman]

Probably best to measure both ways. Since it seems to cycle, it may be difficult to measure. Use a high range on the ohmmeter to measure from slip ring to rotor body, should be infinity.

 

[xjwmx]

rg, if you look at the schematic, the resistor is out of the circuit when the contacts route power to the rotor. It's in parallel with zero ohms at that time. I pointed that out earlier and I have given him the solution to his problem, but he doesn't like it.

 

[freddy3]

xjwmx - Once again, I apologize if I misunderstood something you said. What was it that you suggested? I've asked for a few clarifications, but I don't think I've declined any of your recommendations.

 

[freddy3]

Probably best to measure both ways. Since it seems to cycle, it may be difficult to measure. Use a high range on the ohmmeter to measure from slip ring to rotor body, should be infinity.

Okay, I'll do that - measure resistance between each of the slip rings and, then, each slip ring to the core. I'll report back my results tomorrow evening.
Thanks, all, for the help with this.

 

[xjwmx]

I don't think I've declined any of your recommendations.

What have you done that I recommended? You don't want to fix your bike, you want people on the internet to entertain you. Now, your next post is about testing something that I just told you doesn't make sense. But, if you blast in the dark long enough you're bound to hit something. Hit everything and you'll eventually hit a bulls eye, in this case.

 

[freddy3]

xjwmx, I'm sorry, but, other than where I've asked you for clarification (when I didn't understand what you said or how to do something), I really don't know what you've suggested that I have not tried or done? Like you, I've certainly got better things to do than to tussle with anyone here, so I don't understand why you think that?

Really, I'm just trying to get my bike running again. I'm sorry if my lack of electronic knowledge/experience makes you think I'm wasting your time, but, honestly, to the best of my knowledge, I'm trying everything everyone has suggested (or asked for clarification).

 

[xjwmx]

I really don't know what you've suggested that I have not tried or done?

What happened when you adjusted your voltage down to 14v? You didn't do it. There was a guy here who had everyone involved in fixing his bike. Each one would tell him to try something or make some test and he would make post after post that showed he was ignoring them. They rioted on him and he left in a big huff. The one thing I know you tried that I said was measure that resistor. It was supposed to be a quick check just to eliminate it as a possibility. I told you how to do it after you said you'd had a problem doing it. You come back with a crazy reading that says you did something wrong, and you aren't interested in finding out what that was and doing it right. It was supposed to be a quick check... I'm not going to debug it anymore for you, because I think it will fall on deaf ears but you will eventually get it fixed, one way or another. Just not the neat way.

 

[retiredgentleman]

xjwmx;

I see what you say about the possibility of the current flow through the resistor to a ground within the regulator itself, i.e. contacts fused. But freddy3 said he found no indication of stuck or burnt contacts.

He also said the resistor got hot when he used an NOS regulator. The only thing common to both regulators is the rotor.

He said he measured 15.75 volts, which means the regulator is spending more time with the contacts open causing current flow through the resistor. The contacts move back and forth with current flow making a square wave . If the contacts are open more than closed then the resistor heats up.

That begs the question, why is the output voltage seen to be as high as 15.75 volts? Well, I think a bad rectifier would cause a high output voltage to be seen. freddy3 did a cleaning job on the rectifier, but it may now have become defective after more than 36 years of faithfull service.

So, its likely best to test the rotor, if its bad then replace rotor. If the rotor tests good, then its time to replace the rectifier with a couple of spiffy new bridge rectifiers.

Testing and substitution is the way to find electrical problems. freddy3 is doing a great job by substituting a NOS regulator, and by giving good testing information.

 

[xjwmx]

^I'm handin him off to ya

xjwmx;

Well, I think a bad rectifier would cause a high output voltage to be seen.

But I'll tell you, nothing that can happen to the rectifier would make the voltage go higher, only lower. If higher, they would break it that way to start with...

He said he measured 15.75 volts,

At last count he was measuring some widely varying voltage, and wasn't too intrigued by it. Maybe a bad ground on the probe. Might have clipped it to plastic...

xjwmx;

He also said the resistor got hot when he used an NOS regulator. The only thing common to both regulators is the rotor.

The entire bike, and the installer, and the possibility for adjustment is common to both regulators.

Don't assume the nos reg. is ready to use out of the box with no adjustment. I'm 90% sure all he needs to do is drop his voltage by adjusting the regulator, including the one without the screw. He adamantly refuses to test that hypothesis. That's a Ph.D. for ya.

 

[freddy3]

What happened when you adjusted your voltage down to 14v? You didn't do it.

If you re-read the first page of this thread, I think you'll see that I tried everything you suggested except for this. I tried to explain (apparently, unsuccessfully) that I didn't see any point in trying to lower the voltage on the old regulator because I had replaced it with a NOS regulator. And since the NOS regulator had no effect on the hot resistor, it didn't make sense to dabble further with the old regulator. Doesn't that make sense?

xjwmx;
I see what you say about the possibility of the current flow through the resistor to a ground within the regulator itself, i.e. contacts fused. But freddy3 said he found no indication of stuck or burnt contacts.

That is exactly right. The contacts were very clean and there were no burn spots. Still, since I had the cover off, I cleaned them anyway, but it made no difference.

He said he measured 15.75 volts, which means the regulator is spending more time with the contacts open causing current flow through the resistor. The contacts move back and forth with current flow making a square wave . If the contacts are open more than closed then the resistor heats up.

That makes sense.

That begs the question, why is the output voltage seen to be as high as 15.75 volts? Well, I think a bad rectifier would cause a high output voltage to be seen. freddy3 did a cleaning job on the rectifier, but it may now have become defective after more than 36 years of faithfull service.

The rectifier I just replaced (with the NOS part) was only ~4 years old. This same thing happened once before and, initially, I thought replacing the rectifier fixed it, which is why I got the NOS part. But when you mentioned the rotor, I also remembered that I'd replaced that as well and that may've been the thing that finally solved the problem. But, honestly, it was so long ago that I don't remember what the final fix was?

So, its likely best to test the rotor, if its bad then replace rotor. If the rotor tests good, then its time to replace the rectifier with a couple of spiffy new bridge rectifiers.

When it comes to changing the oem-style parts, I do get a bit difficult. I really do want to keep the bike stock, including the charging circuit. The only part that isn't oem at this point is that rectifier, which I believe is what caused the problem (and the one 4 years ago) in the first place! A shop I took the bike to for a new battery did something to the original rectifier and it was very shortly after that that I had the hot resistor problem (4 years ago). I'm pretty sure that, over a year or so of washings, that new-style rectifier corrodes/rusts and something inside it shorts out, which causes a chain reaction that results, ultimately, in damaging whatever it is that's causing the regulator resistor to heat up. When it comes to electronics, you guys are a bit ahead of me..

Testing and substitution is the way to find electrical problems. freddy3 is doing a great job by substituting a NOS regulator, and by giving good testing information.

Thanks, I really am trying my best with the knowledge/experience/tools I have.

 

[xjwmx]

I tried to explain (apparently, unsuccessfully) that I didn't see any point in trying to lower the voltage

You don't know where I was going with it. You're going to follow your own expertise; you don't need me. That's why I moved on to bigger and brighter things

 

[freddy3]

Not to offend anyone by my absence, but I'm calling it quits for this evening. I'll measure the rotor tomorrow and report back my results. If there's anything more you want me to check, I'll do that as well.

Just fyi: I'm doing all the tests with a Fluke 75 multimeter and I just tested some new (packaged) 220 and 100k resistors and the meter reported their values correctly. So I'm pretty confident that the meter's working to spec.
More tomorrow...

 

[freddy3]

You don't know where I was going with it. You're going to follow your own expertise; you don't need me. That's why I moved on to bigger and brighter things

Understood. Thanks for your help.

 

[Visegrippe]

Check your rotor, if it is shorted, it will draw a lot of current, make your regulator / wiring heat up, as well as drain your battery.

same symptoms i was having ('cept not quite as bad, took a couple of rides to drain the batt).

 

[freddy3]

Visegrippe, did you ever figure out what initially caused the rotor to short out?
It drained my battery, too, but I can't remember whether that happened before or after I discovered the hot resistor?

 

[Visegrippe]

it's old, it had been sitting outside for 20 years, it looks like the insulation just gave way. it was working fine untill i rode it a few times, vibes finally killed it. probably. it seems they have a tendancy to die with age.