TR2/3/3A Another Amp Meter & Regulator Question - TR3A

[SteveBones]

Hello,

I wanted to start out by saying I noticed another thread regarding Amp Meter gauges issues. I wanted to post my own so I can be specific on what I am trying to figure out. My car is a TR3A that I have now back on the road after sitting in a garage for 10 years. You all have been extremely helpful in getting me thru some other challenges including correcting the distributor timing issue a few months back. The car is running great except...........


The issue
-----------

The TR3a gauge amp meter needle is moving or really "swinging or spiking" past the + 20 amp range and back past zero. When I start the car the Amp meter is steady and showing approximately 5 amps. After a short time or when I increase the rpm's on the engine, the amp meter needle then starts to "jump" with quick swings.

Condition of the car
----------------------

I replaced the voltage regulator with the Moss version that was tested prior to shipment. I also replaced the generator. The wiring harness was replaced as well by the previous owner and is in good condition.

What Have I checked (Did I do this correctly?)
-----------------------------------------------------

I measured the voltage from the voltage regulator including the regulator itself and the cut out (great suggestions on this from the other post). I used a digital volt meter and measured based on what is recommended in Haynes manual for the regulator. Going by memory, I call the Haynes manual said the regulator voltage range should be between 16.1 and 16.5 at 50 degrees F. Another publication suggested putting a thin card board piece between the cut out points so the reading will remain steady. I have not tried this with the cut out, but did see a change in the reading so I was not able to confirm the actual regulator voltage. Any suggestions on measuring the regulator voltage range would be much appreciated. As required I also disconnected the 2 wires connected to A and A1 and connected together using a 12 gauge wire to connect.


What is the Real Issue?
-------------------------

I am really trying to figure out why the amp meter needle moves so dramatically. Again the reading is fine when the car is first started but then starts spiking from what I am guessing is a current spike. Any ideas on where to look to isolate and fix would be much appreciated.

Thanks & Happy Holidays!

Steve

 

[TR3driver]

Do the swings steady out if you increase the engine rpm further? What effect does turning the headlights on have?

The paper in the cutout contacts is a substitute for disconnecting the wires from A and A1; there is no need or reason to do both. Either way, the result is to disconnect the battery from the charging circuit, so that you can better observe the regulated voltage (and not have current flowing through the series winding which would affect the regulated voltage). But I would resolve the "jumping around" issue first, before trying to make any adjustments.

I don't understand your comment about "did see a change in the reading". Depending on your DVM, you may have to rev the engine up higher than suggested in the book to get a steady reading and even then it will jump around a bit. Just set so it remains mostly within the window given.

 

[SteveBones]

Randall,

Thanks for the helpful response. Please see below for my comments.

Do the swings steady out if you increase the engine rpm further? What effect does turning the headlights on have?

The swings do not steady out when increasing the engine RPM. I have looked at the swings with the headlights on. I will check this tomorrow and let you know.

The paper in the cutout contacts is a substitute for disconnecting the wires from A and A1; there is no need or reason to do both. Either way, the result is to disconnect the battery from the charging circuit, so that you can better observe the regulated voltage (and not have current flowing through the series winding which would affect the regulated voltage). But I would resolve the "jumping around" issue first, before trying to make any adjustments.

My Response - Good info regarding the paper in the cutout contacts. I also appreciate the explanation on why the A and A1 wires are disconnected. Most importantly, I agree with focusing on the "jumping around" issue before attempting to make any adjustments.

I don't understand your comment about "did see a change in the reading". Depending on your DVM, you may have to rev the engine up higher than suggested in the book to get a steady reading and even then it will jump around a bit. Just set so it remains mostly within the window given.

Thanks for the response regarding the DVM reading. I was not sure what to expect. This is the first time I have tried taking measurements on the regulator and cutoff and was not sure what to expect.

One other item. When the engine is running at 2K RPM, not only is the amp meter needle "jumping", I can also hear and feel clicking from the voltage regulator unit with the cover still on. I expect it is the cut off clicking on and off. This is happening every few seconds. Based on where things stand, I am expecting that the regulator voltage will be fine. I am wondering if the cut off voltage adjustment is off and this is what is causing the amp gauge needle to swing and the voltage regulator unit to be clicking. I am not sure if this is normal or not.

I will go back and do the following:

1) Measure the regulator voltage with A and A1 wires removed from the regulator and wired together. Run the engine RPM to 2K or more before measuring.

2) Check the amp meter swing with the head lights on to see if the needle swing goes away or improves.

3) Also measure the cut off voltage.


Thanks for the help.

Steve

 

[TR3driver]

If the cutout relay is opening and closing, I think there must be a fairly serious problem with either the control box or (more likely) the generator. Might be worth removing the cover and watching to see what is happening. But the ammeter is jumping mostly towards the + side, correct? Does the dash light flicker?

FYI:
When you first start the engine, the control box monitors the output voltage from the generator with it disconnected from the battery. Once the output voltage rises high enough to begin charging, the cutout should close. Once it closes, the voltage (aka shunt) winding will always see battery voltage which should keep it closed. (It takes more voltage to close it in the first place than to keep it closed once it has moved.) Thus once it has closed, it should only open when current starts flowing back into the generator (because the generator isn't turning fast enough to match the battery voltage). There is another coil that monitors the current to/from the generator.

Oh, one other thing to check : Remove the wire from the F terminal, and slip a piece of paper into the regulator contacts (the ones with the screw and locknut on top), then measure the resistance between the F and D terminals (ignition off). It should be around 60-65 ohms. If not, there may be a problem with the "points resistance", located inside the base of the control box. I'm not certain what effect an open points resistance would have, but it might let the cutout drop out under some circumstances.

I tend to place more faith in this document https://docs.google.com/open?id=0B2H2NJt34OffNTc3ODkwYzAtYjRlYS00NDNmLWI0YTYtNjY5ZjQxZTA2NGFm than the Haynes manual.

 

[CJD]

This website is doing it to me again....4th try

Steve,

Just wondered what the charge state of your battery is? If it is low, or you have cranked a lot beforehand, it may be normal to see 20 amps when revved. These meters are undamped, so they bounce a lot even when everything is working properly.

If the "jumping" is abnormally bad, a bad armature winding comes to my mind. When the generator spins over the bad winding (or a dirty spot on the commutaor), the voltage will go dead momentarily. A lot of test voltmeters are damped, so the rapid drop may not show on the meter, although it will on the undamped ammeter. The onboard voltage regulator only looks for the peak voltage, so it will not care about the dead spot as the generator turns...and the bouncing will be worst when the generator is turning at the resonant frequency of the spring in the ammeter, and could even dampen out to nothing at some speeds.

John

(Finally took it)

 

[SteveBones]

Hi Randall,

Thanks for the additional comments. I briefly looked at the document and it shows great detail. I will definitely check it out and let you know when I have an update on what I find.

Steve

If the cutout relay is opening and closing, I think there must be a fairly serious problem with either the control box or (more likely) the generator. Might be worth removing the cover and watching to see what is happening. But the ammeter is jumping mostly towards the + side, correct? Does the dash light flicker?

FYI:
When you first start the engine, the control box monitors the output voltage from the generator with it disconnected from the battery. Once the output voltage rises high enough to begin charging, the cutout should close. Once it closes, the voltage (aka shunt) winding will always see battery voltage which should keep it closed. (It takes more voltage to close it in the first place than to keep it closed once it has moved.) Thus once it has closed, it should only open when current starts flowing back into the generator (because the generator isn't turning fast enough to match the battery voltage). There is another coil that monitors the current to/from the generator.

Oh, one other thing to check : Remove the wire from the F terminal, and slip a piece of paper into the regulator contacts (the ones with the screw and locknut on top), then measure the resistance between the F and D terminals (ignition off). It should be around 60-65 ohms. If not, there may be a problem with the "points resistance", located inside the base of the control box. I'm not certain what effect an open points resistance would have, but it might let the cutout drop out under some circumstances.

I tend to place more faith in this document https://docs.google.com/open?id=0B2H2NJt34OffNTc3ODkwYzAtYjRlYS00NDNmLWI0YTYtNjY5ZjQxZTA2NGFm than the Haynes manual.

 

[SteveBones]

John,

Really helpful comments as it helps with trying to figure out what is going on. So to explore your comments further, and if I understand this correctly, this is what I am thinking:

First off the issue is not with the amp meter voltage level, but really the frequency and level of jumping from the amp meter. I refer to the needle jumping vs bouncing because the needle looks to be reacting to a very sudden current spike. The needle is not only moving in one direction but jumping and swinging 20 amps.

I am wondering if it is the generator, would I be able to isolate and verify via the test of the regulator portion of the control box. This is all new to me, but if disconnecting the wires to A and A1 on the control box, and the amp meter is steady at less than 5 amps, would this mean that the generator is working correctly? Not sure if this is correct. This is the result I witnessed when testing the regulator voltage level yesterday. One item I have not done and will need to is check is the generator itself to see if it working correctly. Currently I am wondering if the cut out is out of adjustment and is the reason why it is "switching" on and off which is causing a current spike and is the reason why the amp meter needle is jumping. I am not sure and learning as I go. Thanks for the response. It really helps me in trying to understand how the recharging system really works.

This website is doing it to me again....4th try

Steve,

Just wondered what the charge state of your battery is? If it is low, or you have cranked a lot beforehand, it may be normal to see 20 amps when revved. These meters are undamped, so they bounce a lot even when everything is working properly.

If the "jumping" is abnormally bad, a bad armature winding comes to my mind. When the generator spins over the bad winding (or a dirty spot on the commutaor), the voltage will go dead momentarily. A lot of test voltmeters are damped, so the rapid drop may not show on the meter, although it will on the undamped ammeter. The onboard voltage regulator only looks for the peak voltage, so it will not care about the dead spot as the generator turns...and the bouncing will be worst when the generator is turning at the resonant frequency of the spring in the ammeter, and could even dampen out to nothing at some speeds.

John

(Finally took it)

 

[SteveBones]

Update on 2 areas including:

1) From the link provided by Randall for trouble shooting, I was able to complete tests 1-4 that cover the generator. All results where positive and expected for a good working generator. I will need to follow up (hopefully tomorrow) on the remaining tests focused on the control unit

2) I also followed up on a couple of helpful questions from Randall. At idle where the tach is showing 1500 rpm, the amp meter reading is steady. I believe the tach reading is approximately 500 rpm higher than the actual engine rpm though not confirmed. As long as the engine remains at idle, the amp gauge remains steady. This includes the gauge needle slowly moving to zero which is expected as the generator recharges the battery.

When I increase the engine rpm to show 2000 on the tack, this is when the amp meter starts "jumping". Looking at it again today, I noticed it is actually jumping or spiking past the + 30 amp level. If I run the engine to the 2000 rpm showing on the tach for 30 or 45 seconds, even after the rpm level returns back to show 1500 rpm, the amp meter continues to swing for another 30 or 45 seconds before "settling" to approx 5 amps with a steady reading.

If I increase the rpm to 2K for one or 2 seconds, the amp meter will "jump" as described before, but when the rpm is back at idle showing 1500 rpm, the amp meter will "settle" to a stable 5 amp or less reading after only one or 2 seconds.

I will be away from the forum until sometime tomorrow and will check back when I return.

This is another one of those exploration exercises where all the "fun" is in figuring out how to trouble shoot and isolate. I greatly appreciate the valuable help. Without it, I would not be able to figure this out while also using a few brain cells in a constructive way.

Thanks,

Steve

 

[CJD]

I am curious what the voltage shows between the battery posts when you see the 30+ amps...

My generator is still the original, and it is only good to about 20 amps. If you only see 14 volts or less, I am leaning towards an overly sensitve ammeter. If the voltage is spiking, along with the ammeter, to 15v or higher, then I think we need to concentrate on your voltage regulator.

Also, when the ignition is off, does the ammeter needle go to 0?
John

 

[Brinkerhoff]

Check battery. Nothing will ruin a generator like a battery with a bad cell. It will cause the generator to overwork and overheat. Check the ground strap to the engine for tightness and cleanliness, as well as the battery terminal connections. Kevin

 

[SteveBones]

John,

Good questions. Here is what I am thinking. The swing or spike from the amp meter to 30+ is not a steady reading. I expect that the current amount is less than 30 amps. The swing I believe is caused by a sudden "burst" of current based on the sudden movement where the needle looks to "jump". The document link that Randall provided outlines a series of tests to run that helps isolate the issue. I completed the first 4 that focus on the generator which looks good. The remaining tests focus on the control box (regulator and cut out) in addition to the wiring that connects the recharging system. I agree that the issue is with the cut out not working correctly. From the document, I expect to be able to confirm and determine if this can be solved via adjustment vs replacement. Before starting this post, I was not really sure what was causing this.

I needed to replace the generator because it was also original, the armature (sp?) had pieces missing where the brushes meet up (the communicator?). I partially rebuilt the original, and will finish it later and use as a spare. The price for a new armature from Moss is reasonable, and the local parts and machine shops helped with removing the original bearing. Part of the what I enjoy from doing some of the work myself, is all the help and people I meet along the way that share the same passion for old vintage cars. Thanks for the help and suggestions.

Steve

I wanted to confirm that with the ignition off, the ammeter drops or move back to 0.

I am curious what the voltage shows between the battery posts when you see the 30+ amps...

My generator is still the original, and it is only good to about 20 amps. If you only see 14 volts or less, I am leaning towards an overly sensitve ammeter. If the voltage is spiking, along with the ammeter, to 15v or higher, then I think we need to concentrate on your voltage regulator.

Also, when the ignition is off, does the ammeter needle go to 0?
John

 

[SteveBones]

Kevin,

Thanks for the suggestions. The battery is new so I am good there. Good suggestion regarding the ground strap. My previous car that I purchased a while back had not been running and needed major work. After getting it all back together, the starter would be slow to move and the battery ground connection would heat up. It took me awhile to figure out it had to do with the ground strap to the engine either being loose or not connected.

Thanks,

Steve

Check battery. Nothing will ruin a generator like a battery with a bad cell. It will cause the generator to overwork and overheat. Check the ground strap to the engine for tightness and cleanliness, as well as the battery terminal connections. Kevin

 

[TR3driver]

This is all new to me, but if disconnecting the wires to A and A1 on the control box, and the amp meter is steady at less than 5 amps, would this mean that the generator is working correctly? Not sure if this is correct.

With the A & A1 wires disconnected, the generator and control box are basically isolated from the battery and hence cannot charge at all. You should see only a few amps of discharge on the ammeter, indicating that the ignition is drawing current from the battery. If you see any charge at all, there is something wrong with the wiring (likely that the wires to the ammeter are reversed). And since the generator isn't connected to the ammeter, the ammeter reading tells you nothing about the generator or control box condition.

At this point, I think what you have are components that are basically working, but there is an intermittent short or open some place that is aggravated by engine vibration. Maybe the ground wire to the control box is loose? However, I would go ahead and complete steps 5-9 (part 2) of the tests in the booklet, as they include the cutout checks.

 

[SteveBones]

OK - I have an update regarding the control box. I finished up to test #8 on the extremely helpful document provided by Randall. The test confirmed that the regulator itself is set correctly and the generator is also working as it should.

I did find an issue with the cut off unit based on test # 8. The result should be where the voltage measurement starts at the battery level, which I measured at 12.9 volts, and increases in 0.5 to 1 volt increments up to the regulator voltage setting which I measured and adjusted to 16.2 volts as recommended per the document.

The actual result I measured with the cut out contacts connected was zero which is one of the results listed in the document. The recommendation is to clean the cut off contacts so there is an actual closed circuit when they are connected. I can not recall what was recommended to clean the cut out contacts so I will need to check this out. I plan to follow up on this tomorrow.

From my perspective this was a great exercise. Not only was I able to confirm what is not working and a recommendation to fix, I was also able to confirm what WAS working. It beats having to go through the random part replacement exercise.

Thinking back, I replaced the voltage regulator box before the generator. The generator was original. When I pulled it out and inspected I found one of the brushes completely worn away so that all was left was the wire itself hanging free, and a couple of pieces of the ammerature (sp?) had fallen off. I am not sure if this might have caused the issue with the new voltage regulator cut out. At least now I know what is causing the issue with the amp meter gauge needle "jumping". I am thinking that worse case I will need to replace the voltage regulator in order to get this resolved.

Steve

 

[SteveBones]

With the A & A1 wires disconnected, the generator and control box are basically isolated from the battery and hence cannot charge at all. You should see only a few amps of discharge on the ammeter, indicating that the ignition is drawing current from the battery. If you see any charge at all, there is something wrong with the wiring (likely that the wires to the ammeter are reversed). And since the generator isn't connected to the ammeter, the ammeter reading tells you nothing about the generator or control box condition.

Thanks Randall, I understand this now. I also wanted to confirm that the amp meter did not show any charge when running this test. I did not realize at the time that when A1 and A are disconnected, the battery and generator are not "connected".

At this point, I think what you have are components that are basically working, but there is an intermittent short or open some place that is aggravated by engine vibration. Maybe the ground wire to the control box is loose? However, I would go ahead and complete steps 5-9 (part 2) of the tests in the booklet, as they include the cutout checks.

I thought so as well regarding any loose connections. When finishing the generator tests with the leads removed, I made sure the brass nuts were tight (this is the older type generator). I also noticed that the wire tab connector to the D and F tab locations on the control box were a bit loose and fixed this as well. Unfortunately this did not resolve or improve what I am seeing from the amp meter.

 

[TR3driver]

The actual result I measured with the cut out contacts connected was zero which is one of the results listed in the document. The recommendation is to clean the cut off contacts so there is an actual closed circuit when they are connected.

That's interesting. I have always wondered how that would be possible; assumed it was a misprint/mistake in the booklet. The 'A' terminal is connected to the battery through the ammeter, so if the voltage at that point is significantly below battery voltage, there will be a huge amount of current flowing somewhere. Zero volts is going to let the smoke out quicker than you can measure it!

Also, with the circuit to the battery complete, the voltage is never going to rise as high as the regulated open circuit voltage. Since even a fully charged battery will take a good deal of current at 16 volts, the current (series) winding on the regulator will, in effect, lower the regulated voltage.

a couple of pieces of the ammerature (sp?) had fallen off.

Do you mean the copper segments where the brushes ride? That is the commutator. Likely the damage was done when the brush twisted out of the holder (which also crushed the brush). It is possible that the cutout contacts could have been damaged by the same event. If it was the 'hot' brush and the bare wires shorted to ground, the resulting fault current could have done in the cutout; but I would think you'd see some damage in the yellow wire to the generator as well.

 

[SteveBones]

That's interesting. I have always wondered how that would be possible; assumed it was a misprint/mistake in the booklet. The 'A' terminal is connected to the battery through the ammeter, so if the voltage at that point is significantly below battery voltage, there will be a huge amount of current flowing somewhere. Zero volts is going to let the smoke out quicker than you can measure it!

Good point. Since this measurement is at the cut off (and not the regulator), the result to me means that the cut off, which is acting as light switch to turn on or off the flow of current between the generator and the battery. So the regulator is working but the "circuit" is not complete because the cut out points need to be cleaned. I recall reading something where the cut off (switched off or open) is needed when the generator current level is lower than the battery. Without the cut off points open, under these conditions, the fully charged battery would otherwise loose its charge as the current would flow from the battery to the generator. I need to think about this some more as I am not completely sure. You are definitely bringing up some very good points.

Also, with the circuit to the battery complete, the voltage is never going to rise as high as the regulated open circuit voltage. Since even a fully charged battery will take a good deal of current at 16 volts, the current (series) winding on the regulator will, in effect, lower the regulated voltage.

Good points. I need to think about this. I was thinking that the higher voltage allowed by the regulator would result an increase in current coming from the generator to the battery to recharge. As the battery is recharging, then the regulator voltage level would decrease or which is "regulating the level of voltage needed based on the charge state of the battery. I am not sure if I understand this correctly, and will need to think about it a bit.


Do you mean the copper segments where the brushes ride? That is the commutator. Likely the damage was done when the brush twisted out of the holder (which also crushed the brush). It is possible that the cutout contacts could have been damaged by the same event. If it was the 'hot' brush and the bare wires shorted to ground, the resulting fault current could have done in the cutout; but I would think you'd see some damage in the yellow wire to the generator as well.

Yes, I was referring to the commutator. I could not remember what it was called. Thinking about this, when I first installed the voltage regulator with the original generator, when idling at night, I noticed sparks of electricity coming from the inside of the generator looking through the end where the F and D wires connect along with where the brushes are located. When I took the original generator apart, I noticed spots of what looked like splattered solder that appeared to get hot, become liquid, and where spun off the armature where it solidified. So it looked like something was going on (and heating up) in a way that was not how the generator was designed to operate. This could be the reason why the cut off is not working or specifically why the cut out points are not working. I will check this out later today

Thanks again for the comments. I am really learning quite a bit on how the various recharging items really work (or should be working).

Steve

 

[TR3driver]

When I took the original generator apart, I noticed spots of what looked like splattered solder that appeared to get hot, become liquid, and where spun off the armature where it solidified. So it looked like something was going on (and heating up) in a way that was not how the generator was designed to operate.

Yup, thrown solder is a fairly common problem. At least in my experience, it usually results from having the regulator mis-adjusted, or a battery with a shorted cell (as Kevin mentioned). It doesn't take much more than the rated current (19 amps for the early unit, later units 22 amps) to overheat the armature. The generator will easily produce more, so it is only the action of the regulator that keeps it from burning itself up.

Usually, there are also one or more armature windings that are shorted to the armature (insulation breakdown), so even re-soldering the wires won't fix it.

 

[SteveBones]

The problem is solved. The jumping amp meter gauge needle was caused by a loose wire under the dash. The loose wire is the white with red wire connected to the starter button. I am now on to another item tied to the wiper motor that I will post on another thread. Thanks everyone for the helpful suggestions. Randall suggested it might be a loose wire. I was looking for the loose wires inside the engine compartment yesterday and did not even think to check behind the dash until today.

Steve

 

[TR3driver]

Cool, glad you solved it.