Checking voltage regulator

JOB

Member
I just had the generator on one of my stationary engines rebuilt. (brushes and bearings) The amp. gauge still reads zero. How would you test the voltage regulator to see if it is working?
 
(quoted from post at 19:59:10 10/23/13) I just had the generator on one of my stationary engines rebuilt. (brushes and bearings) The amp. gauge still reads zero. How would you test the voltage regulator to see if it is working?
nsufficient details.
 
I kind of thought that generators were pretty much
all the same.

This is on a 1965 Ford power unit. The generator
has the Field, ground and the armature terminals
on it. the regulator is behind the sheet metal so
it is not real visible. It does have four
terminals on it. Armature, field and ground, the
fourth terminal going to the amp gauge. From the
amp gauge to the starter solenoid where the
positive connects. I was guessing this is the same
as all the older tractors.
 
"I was guessing this is the same
as all the older tractors."

WRONG guess. Troubleshooting procedure will depend upon whether it is a "A" system or a "B" system.

Terminal markings on gen and reg are the same, functionality is NOT.
 
In the event the Generator and VR are Class A circuits, my Troubleshooting Procedure below in Para 5 tells you how to effectively by pass the VR function by dead grounding the gennys FLD post to see if she charges then to determine if non charging is the genny itself fault or a VR or another problem.

If its a Class B system (some Fords and some Masseys I believe) its a different test by which you full field the genny DONT USE MY A METHOD FOR CLASS B SYSTEM

John T
John Ts Class A Troubleshooting
 
I learn something new everyday. I thought it might be as simple as putting a meter from this wire to that one and checking the current going through.
 
As John said most Fords (Autolite) will be a B circuit system while most Delco units will be A circuit. Personalty I have never seen different but every time I use an absolute I get shot down, LOL.
The difference between an A and B type is basically which end of the field (F) circuit is grounded and which end is fed voltage from the battery. The A type is grounded by the regulator and fed internally while the B type is grounded. internally and fed from the regulator. Important to know because a basic system test is to give the field full voltage. Good trouble shooting guides are as easy as searching you topic heading but add "generator"
Some things you can check. Does the ammeter even work? Put a volt meter on the battery and check voltage while running. Should be mid 13s-14 if 12V and 7s if 6V. Check grounds. The genny, and regulator both must have good grounding. Did you polarize it after you installed? It should be OK if they ran it on a machine but have seen it not be.
 
What side of the ampere gauge do you connect the wire from the regulator? - or +. I always thought the + was the battery side of the amp gauge?

The sheet metal of the engine house was painted this past summer, that is what the voltage regulator is bolted to. There is a ground wire from one of the mounting bolts. Where that ground wire goes to ground I do not know.

I thought it would be a simpler fix that this I will need to find out where wires go instead of relying on the way it was wired when I got the engine. Electrical is not one of my strong points.
 
(quoted from post at 12:55:45 10/24/13) What side of the ampere gauge do you connect the wire from the regulator? - or +. I always thought the + was the battery side of the amp gauge?

The sheet metal of the engine house was painted this past summer, that is what the voltage regulator is bolted to. There is a ground wire from one of the mounting bolts. Where that ground wire goes to ground I do not know.

I thought it would be a simpler fix that this I will need to find out where wires go instead of relying on the way it was wired when I got the engine. Electrical is not one of my strong points.
965? Should then be 12volt negative ground. In that case, Battery+ goes to Ammeter Negative terminal and ALL loads/gen/VR output(BATT) go to ammeter Positive terminal.
VR ground should connect to generator ground.
 
It depends on if its Pos or Neg ground. If an ammeter registers bass ackwards, all you do is reverse the leads. If on a tractor etc that has a correct wired ammeter if you turn lights or ign etc on when she's not running, the ammeter should swing over to the - discharge side but then if running and the genny works it will swing to the + charge side and if it does opposite of that simply reverse the leads. The ammeter is just an in line series passive device to register current flowing INTO/charging the battery or out of discharging.

Regardless and to standardize things REGARDLESS OF POLARITY I tell people theres ONLY ONE wire on the SUPPLY SIDE of the ammeter and it wires to the hot UNGROUNDED battery post. On the other LOAD SIDE theres often TWO WIRES, one to loads like lights and ignition, the other to the BAT terminal on a Voltage Regulator.

To work BOTH the gennys case frame and the VR case frame must be grounded i.e. connected to the frame grounded battery post or frame ground connection.

On some trucks/cars/tractor wiring diagrams I've seen on NEG ground systems the ammeters + wires to battery + and loads and gennys output (BAT on VR) wire to the - of ammeter.

If its an A system my Troubleshooting Procedure in Para 5 will tell if non charging is a genny versus VR or other problem.

John T
Troubleshooting
 
I currently have the amp gauge wired backwards, I
will change. If I read your post right the voltage
regulator itself (not one of the terminals on the
regulator) grounds to the ground terminal on the
generator???
 
Somewhere I saw "is the amp gauge good?" Do they go bad and is there a way to test it to find out?
 
I wouldn't worry about re-wiring ammeter unless you see a load indicating charge (instead of discharge). Just connect a headlight bulb or any substantial load to the non- battery side of the ammeter & watch indication.
Yes, on your VR ground question, ground is the case.

If you are interested, I can't tell you how to test the regulator without more equipment that about 99.44% of tractor owners are likely to have available, but by process of elimination, I can tell you how to make it charge without VR, thus proving generator is good (just re-built, so I guess you know it is good) and that problem would then be VR or wiring.

And my procedure does not matter whether it is "A"-ckt or "B"=ckt.
 
When I picked up the generator from the shop, I was told the brushes were stuck away from the commutator (I think that is the right term) and the bearings were shot. He said it looked like the generator had been out in the weather for awhile. So that is why I am wondering about the regulator. Maybe the inside of that is all corroded up?????

It is easy to change the wires around on the amp gauge. When I was running it I did not see a charge going backwards through the amp gauge.
 
Sure they can go bad, Ive seen many where the needle is mechanically stuck (rusted) and doesn't move. However they don't often go bad such as an open circuit. As long as they are continuous they still can pass current even if the needle is stuck and cant move. An "ideal" ammeter is zero ohms.

One test is to pass a magnet across its face and see if the needle moves back n forth. Another test is an ohmmeter and it should be continuous and read very low ohms.

Par 5 of my troubleshooting procedure is an easy way to see if non charging is the fault of the genny or VR or other causes...for a Class A system

To be safe Id polarize the genny, see my procedure for how.

John T
Charging Troubleshooting
 
Many years ago I welded on a truck with an AC buzz box and de-polarized the generator. Never did figure out what was wrong with it until many years later. Did not have a place to get help full friendly advise like this site.

This generator was just gone through by a re-builder that has done a lot of work for me over the years, I am banking that this generator has the polarity correct. I am a little bit afraid of messing something else up.

I will re-wire my amp gauge. The regulator is in a hard to get at spot, will take that off and look inside. Make sure the regulator case in grounded to generator and see what happens.
 
Watch the ammeter when the engine is cranking.It should move from zero to 4 amps discharge as the ignition points open and close.On a tractor with lights turn on the lights you should see a discharge of 10 amps or more.
 
The amp gauge I can make the needle move negative with a magnet, to the ten amp line. It will not move from zero to positive at all.

An ohm meter says 01.2, is that low for ohms?
 
"This generator was just gone through by a re-builder that has done a lot of work for me over the years, I am banking that this generator has the polarity correct."


That's not necessarily so. He could have polarized it at Neg ground like late model cars use orrrrrrrrr the could have polarized it at Pos ground like many old tractors used

NEITHER IS RIGHT OR WRONG it can be polarized correct at Pos or Neg. But if you hook it up and start it and the genny was at opposite polarity from the way you wired it ITS POSSIBLE TO FRY THE VOLTAGE REGULATOR.

"I am a little bit afraid of messing something else up."

YOU DO NOT MESS UP A GENNY BY POLARIZING IT TO MATCH YOUR SYSTEM it can work at EITHER polarity... But if its at the wrong polarity because you were afraid to polarize it correctly to match your system YOU CAN MESS THINGS UP (the VR)

You can still polarize the genny even if the VR is hard to get to. Simply use a jumper wire etc to momentarily flash jump from the hot ungrounded battery post to the gennys ARM post (for a Class A system) The genny is what gets polarized NOT the VR

John T
 
See if it moves if you reverse (swap North and South ends) of the magnet?? Its still possible the ammeter needle may be rusted/stuck I just cant say from here

The 1.2 ohms don't sound bad, an "ideal" ammeter would have 0 ohms but that's not been made yet.

REGARDLESS of the ammeter put a volt meter on the battery and setting it should read around 12.6 but if coupled to a good working charging system at fast RPM it should rise to at least 13 and up to 14 volts depending on battery and genny and RPM

John T
 
I had the amp gauge wired wrong. It is now wired correct. The engine is a stationary power unit so there is no lights, just the ignition system. I will start it today (Saturday) and watch the gauge.
 
John, I should have got this done sooner but another job and weather interfered. I did the voltage check and I get less battery volts when it is running that before. So I would say something is amiss. I would bet it is the regulator. I never did take it off and apart.

As for the magnet and the amp gauge, the magnet I used was at the end of a pick up tool so no north and south poles. another gauge I found will only go positive with two different magnets.

I think I will just spring for a regulator.
Thanks for your help
 

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