Blowing voltage regulators

-
IIRC OP stated this all started when he replaced his single field wire alternator. Perhaps the OP should try another alternator?

the VR101 is (and Im 99% sure of this) an all electrical voltage regulator housed in a electro-mechanical style housing. the only way to "blow them would be to short the output to the alternator. (as others have said) the alt has a short in the field coil but it is intermittent that would explain the symptoms.

you can completely bypass the electrical wiring in your car by removing the field and heavy supply wires off the alternator, removing both the wires off the voltage regulator and running some jumpers.


run a jumper from one field wire of your 2 field wire alt to battery negative
run a jumper from the VR case to battery negative
run a jumper from alt case (housing) to battery negative
run a jumper from alt output ( heavy wire /Large lug) to the battery Plus
run a jumper from battery plus to the ignition side of the VR.
Run a jumper from VR field to the other field wire of your 2 wire field alt

start engine and see what you get at the battery.


@Mattax would you review my logic!

this is how I would start to be sure the alt and VR are working correctly, then I would start tracing wires and see if there are any with cuts to the insulation, kinks that might have resulted in broken strands, melted areas where wires could be touching etc

Side note about melted wires. along time ago I worked for an office building doing Fac Operations. we had a outdoor cooling tower that kept blowing its cir barker.

i noticed that it only happened a day after it rained. so I convinced the engineer to look at the wires in the metal conduit near where someone had been doing some welding. sure enough the wires inside had been heated enough to cause the entire group to be melted together and sure enough that day it was the day after a rain and sure enough the wires were wet.

moral to the story... it can happen!
 
Last edited:
Dana67Dart said:
IIRC OP stated this all started when he replaced his single field wire alternator. Perhaps the OP should try another alternator?

the VR101 is (and Im 99% sure of this) an all electrical voltage regulator housed in a electro-mechanical style housing. the only way to "blow them would be to short the output to the alternator. (as others have said) the alt has a short in the field coil but it is intermittent that would explain the symptoms.

you can completely bypass the electrical wiring in your car by removing the field and heavy supply wires off the alternator, removing both the wires off the voltage regulator and running some jumpers.


run a jumper from one field wire of your 2 field wire alt to battery negative
run a jumper from the VR case to battery negative
run a jumper from alt case (housing) to battery negative
run a jumper from alt output ( heavy wire /Large lug) to the battery Plus
run a jumper from battery plus to the ignition side of the VR.
Run a jumper from VR field to the other field wire of your 2 wire field alt

start engine and see what you get at the battery.


@Mattax would you review my logic!

this is how I would start to be sure the alt and VR are working correctly, then I would start tracing wires and see if there are any with cuts to the insulation, kinks that might have resulted in broken strands, melted areas where wires could be touching etc

Side note about melted wires. along time ago I worked for an office building doing Fac Operations. we had a outdoor cooling tower that kept blowing its cir barker.

i noticed that it only happened a day after it rained. so I convinced the engineer to look at the wires in the metal conduit near where someone had been doing some welding. sure enough the wires inside had been heated enough to cause the entire group to be melted together and sure enough that day it was the day after a rain and sure enough the wires were wet.

moral to the story... it can happen!
Click to expand...
Seems correct to me also.

I was going to suggest leaving the heavy alternator wire connected. Then after reading your story, I can see why you suggested taking it off for the initial test.
So my only suggestion is to call the metal tabs terminals.

run a jumper from one field terminal of your alt to battery negative
run a jumper from the VR case to battery negative
run a jumper from alt case to battery negative
run a jumper from alt output ( heavy wire /Large lug) to the battery Plus
run a jumper from battery plus to the ignition side of the VR.
Run a jumper from VR field to the other field terminal of your 2 wire field alt

start engine and see what you get at the battery.
 
Every legitimate question on this site, results in an informational prick waving contest of epic proportions. I receive a lot of info here....and I'm very thankful for that. It's just sad that simple questions can't be answered here anymore.
 
Care to elaborate? Which question in particular ended up with dick waving?:welcome::popcorn:
helliphinon8 said:
Every legitimate question on this site, results in an informational prick waving contest of epic proportions. I receive a lot of info here....and I'm very thankful for that. It's just sad that simple questions can't be answered here anymore.
Click to expand...
 
helliphinon8 said:
Every legitimate question on this site, results in an informational prick waving contest of epic proportions. I receive a lot of info here....and I'm very thankful for that. It's just sad that simple questions can't be answered here anymore.
Click to expand...

Until you start paying me (and the literal "me," the "us") our imagined consultation fees, we are "working here" for free. Nobody is paying anybody to spend time here. And you might keep in mind that not all the "simple" problems here turn out to be that simple. Also, "we" can't see what YOU are dealing with. We don't know what's in your mind, what you have checked, or what you think you have checked and made a mistake, thus skipping a potential cause. A lot of us are just plain getting old. At some point we start to forget. I'm truly sorry we cannot be the perfectly organized wealth of information, always correct, always spot on.
 
This is a information sharing forum it is up to readers to sort it out. Lots of interesting posts and problems, what REALLY aggravates me is when the OP
solves the problem(s) and does not share.
 
Any thoughts? I've had 2 VR's go out, same failure at the fusable link. These were both NAPA VR32's.

20200101_175234.jpg
 
66jim said:
This is a information sharing forum it is up to readers to sort it out. Lots of interesting posts and problems, what REALLY aggravates me is when the OP
solves the problem(s) and does not share.
Click to expand...

I will not call out this forum any more than any of the rest I frequent but when it comes to the repair action found to correct the problem, the large majority of them were self induced due to poor work practices or flat out not knowing how a system truly works....many folks will not return to the scene of the crime sporting egg on their face....
 
sprue said:
Did you find an answer on this? I blew the same wire on mine.
Click to expand...
Are you talking about the fusible links?
One or both?
They melt when there is too much current drawn through them as explained here
Blowing voltage regulators

Knowing which one (or both) you can look for what caused that.
if it doesn't make sense - ask.
 
bigaadams said:
I will not call out this forum any more than any of the rest I frequent but when it comes to the repair action found to correct the problem, the large majority of them were self induced due to poor work practices or flat out not knowing how a system truly works....many folks will not return to the scene of the crime sporting egg on their face....
Click to expand...
No answer? Egg on the face!
 
Mattax said:
Are you talking about the fusible links?
One or both?
They melt when there is too much current drawn through them as explained here
Blowing voltage regulators

Knowing which one (or both) you can look for what caused that.
if it doesn't make sense - ask.
Click to expand...
The fusible link for the upper contact melted. So if I'm reading correctly the problem is not enough resistance in the alternator and replacing the fusible link would not solve the problem. Might as well buy one of those new alts with the built in regulators.
 
sprue said:
The fusible link for the upper contact melted. So if I'm reading correctly the problem is not enough resistance in the alternator and replacing the fusible link would not solve the problem.
Click to expand...
Correct.
sprue said:
Might as well buy one of those new alts with the built in regulators.
Click to expand...
Whoa! Hang in there. There's some potential problems with that solution.

Maybe I should have written "mostly correct". It could have shorted before the alternator.
With the fuse to upper contact blown, we know two things.
1. The electromagetic coil in the regulator wasn't pulling very hard. In other words, the voltage was low.
2. Too much current went through the regulator because it found an easy path to ground.

So here's where to look next.
a. The connecting wire from the regulator to the alternator's 'field' terminal. If any part of that wire touched a ground, even briefly, while the key was in run, that would melt the fuse.
b. At the alternator, if any part of the field circuit grounded. Can try to check with a multimeter. We can walk you through that.
Visually, check the field terminal (the one green wire plugs into) and the brush and brush holder. The brushes and brush holders are easy to replace.
If the slip rings or rotor windings are grounding that might be best to have fixed at a shop.
 
Last edited:
This field wire could have caused a short if it contacted the alternator housing even if it still had the connector cover on it.
upload_2020-1-23_17-4-32.png


The field terminal on the left must be isolated from ground.
upload_2020-1-23_17-10-13.png


It connects to a carbon brush. The brush holder is non-conductive. These are easy to take out and check.
upload_2020-1-23_17-12-40.png


upload_2020-1-23_17-13-21.png


If the ground brush is removed first (on right in above photo) there should be no continuity between the field terminal and the housing.
 
Just to complete the picture, here's what the slip rings and rotor look like.
upload_2020-1-23_17-27-27.png
 
Last edited:
just had to have my voltage regulator replaced - apparently at some point a hangry mouse got into my dash - no idea how long the situation existed before failure.
 
It very possibly could have grounded on the case. I also have no clue what this third wire is supposed to connect to.

20200124_210312.jpg
 
helliphinon8 said:
Any thoughts? I've had 2 VR's go out, same failure at the fusable link. These were both NAPA VR32's.

View attachment 1715446393
Click to expand...

Too much current in the field circuit. Another cause, other than something shorted/ shorting, is TOO MUCH FIELD CURRENT. There is a procedure in the service manuals to measure that. It could be a partially shorted alternator field (rotor.)

If you have not, I would pull the alternator apart and give it a good inspection. Look for cracked/ loose/ other problems where the brushes might be grounding out, as well as checking field current.

What is with the wire coming out of the alternator Is that yours?
 
67Dart, It's not coming out of the alternator it's just sitting on top. I think it used to be the temp sensor which has a different wire now.

I also ran a wire off the connection at the resistor in order to get 12V to the the carburetor's automatic choke. That wouldn't change the voltage at all but it would split the current between the carb and the regulator/field. Could that mess it up?
 
sprue said:
I also ran a wire off the connection at the resistor in order to get 12V to the the carburetor's automatic choke. That wouldn't change the voltage at all but it would split the current between the carb and the regulator/field. Could that mess it up?
Click to expand...

In a roundabout way, it will / may cause OVER charging.. I've posted a bunch about voltage drop in the ignition feed causing overcharging because it feeds the voltage regulator low voltage. So if you put extra load on that circuit point, it will drop further. However the factory did the choke just that way. This problem is why I advocate "for a simple fix" to cut the ignition (IGN1 or ignition run) coming out of the bulkhead, feed a relay coil, and then connect the load contacts to the engine bay end of the wire you cut. Feed the relay with a large fuse/ breaker off the starter relay.

But for later LOL. I'd worry about this problem now
 
67Dart273 said:
In a roundabout way, it will / may cause OVER charging.. I've posted a bunch about voltage drop in the ignition feed causing overcharging because it feeds the voltage regulator low voltage. So if you put extra load on that circuit point, it will drop further. However the factory did the choke just that way. This problem is why I advocate "for a simple fix" to cut the ignition (IGN1 or ignition run) coming out of the bulkhead, feed a relay coil, and then connect the load contacts to the engine bay end of the wire you cut. Feed the relay with a large fuse/ breaker off the starter relay.

But for later LOL. I'd worry about this problem now
Click to expand...
I didn't quite follow all that, but I was thinking of just redoing the whole harness with this Speedway Universal 22 Circuit Wiring Harness
 
^^^^^ agree, do not run the electric choke from the ballast. Original wiring compounds the issue for the charging system. Like said do a mod or find a better way to feed the choke power!
 
sprue said:
It very possibly could have grounded on the case. I also have no clue what this third wire is supposed to connect to.

View attachment 1715458222
Click to expand...


That violet/purple is most likely the temp sender wire!

You clearly have the old wiring syndrome. Start budgeting the cash to replace some or all of it. I recommend at a minimum the engine harnesses!
 
Everywhere you see a crack in the insulation you can bet the wire is corroded another 4” at least.

If you want custom, then your bet and ability to get the right solution. You want reliability, buy a new stock plug and play harness from M&H provided from YearOne or maybe Classic! JMO!

Also if that violet is grounding to the Alternator case it is hurting the dash Instrument VR! Isolate that for sure!
 
Last edited:
You must log in or register to reply here.
-

Back
Top