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Tractor Talk Discussion Forum

Generator/voltage regulator problems.

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MBU

03-27-2007 21:57:46




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I posted this in the Massey Ferguson section and didn"t get a response. So maybe someone here can help, as it is a problem not necessarily dependent on tractor type...

I have a MF 65 Diesel tractor. The generator is a three-brush type.

The ammeter shows that when I start the tractor the system is discharging about 10 amps. However, once the tractor gets started the ammeter show it charging about 10 amps, but within a minute, the ammeter starts jumping between -20 to +20 on a plus and minus 30 amp scale. There is no load on electrical system like lights etc.

Is my voltage regulator a problem or what?

Thanks...

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souNdguy

03-28-2007 08:05:26




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 Re: Generator/voltage regulator problems. in reply to MBU, 03-27-2007 21:57:46  
i got a question.. you said it was a 3 brush job.. 3rd brush gennies usually have a cutout realy only.. and have an adjustable brush holder on the back of hte genny..

the 2 brush gennies have the vr..

so which you got?

is it a circuit or b circuit?

never mind.. I'm guessing worn brushes or tall mica.. pull it down and see if the mica needs to be undercut ( hacksaw balde.. )

Soundguy



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MBU

03-28-2007 13:37:06




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 Re: Generator/voltage regulator problems. in reply to souNdguy, 03-28-2007 08:05:26  
SoundGuy,

Not too sure what you mean. The generator has 3 brushes and a voltage regulator. I am not aware of any "cutout" - would you mind explaining further?

Thanks...



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soundguy

03-28-2007 14:11:23




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 Re: Generator/voltage regulator problems. in reply to MBU, 03-28-2007 13:37:06  
Lots of 3 brush jobs just have a cutout relay. ( to prevent backflow of current into genny when it is not running ) - A VR will have a cutout built into it.

I have seen some that do use a voltage regulator.. I was just wondering if that was an oem setup on yours, or one changed out.

Soundguy



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MBU

03-28-2007 17:50:32




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 Re: Generator/voltage regulator problems. in reply to soundguy, 03-28-2007 14:11:23  
Soundguy,

Okay...I see what you mean now! I'll check that out.

I was just going by the schematic in my manual and assumed it represented a 3 brush generator. To me the 3 brush generator is just too old to be on this tractor, but that's what it is! Perhaps it was replaced at some point in time by my father and the parts guy gave him this one. This has been a problem for a long time and it goes thru a battery about every year. Thought is was about time to get it fixed! Since it is a small tractor I don't use it much but other than the battery problem it 's runs great. It has a Perkins diesel and it runs forever on a tank of fuel. Great for those small jobs!

Mike

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Gerald J.

03-28-2007 08:58:45




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 Re: Generator/voltage regulator problems. in reply to souNdguy, 03-28-2007 08:05:26  
After I rebuilt the generator with new brushes and pulley and polished the commutator, I added an ammeter on my gas JD 4020. It bounced from peg to peg. I ascribed that to a slow regulator but I couldn't tell whether the generator was doing me any good (I could see a slight spark at the brushes as if it was working), but I knew I had to put a charger on the battery for many morning starts. And battery life was short, only a year. Expensive for the 3EE battery.

Since a new regulator was $35, I ripped off regulator and generator and put on a 10SI internal reegulator alternator with a special small wide pulley. It charges correctly and rapidly, I got three years from the new side terminal battery (from wally world) sitting out on the new step. I kept the generator and regulator for restoration should I do that some eon, but in the mean time I've not had to put a charger on it in years.

Some of the new auto store aftermarket regulators look like they are electromechanical but are solid state and should be a drastic improvement over the original style regulators.

And for a few projects, I've built my own regulators that worked very well.

Gerald J.

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MBU

03-28-2007 07:25:36




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 Re: Generator/voltage regulator problems. in reply to MBU, 03-27-2007 21:57:46  
Thanks Guys!

I will test out your suggestions and get back with you sometime today or tomorrow!



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John T

03-28-2007 04:42:24




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 Re: Generator/voltage regulator problems. in reply to MBU, 03-27-2007 21:57:46  
MBU, Yeppers you could well have a VR problem (The VR's internal relay contacts might simply be dirty or corroded or sticking or mis adjusted or its not well grounded) and below is a test to determine whether the problem is generator or VR related (you simply by pass the VR functions, see below). However, other things like A LOOSE CONNECTION OR A POOR GROUND OR THE VR ISNT WELL GROUNDED can cause similar problems. Make sure the belt is good n tight (maybe it slips then heats up???) and remove n clean n wire brush n reattach all the VR and genny and grond connections. CHECK EASY SIMPLE THINGS FIRST LIKE A LOOSE OR BAD WIRING CONNECTION OR GROUND OR A LOOSE BELT.

Possible genny problems could be,,,,, ,, the commutator is burned or pitted or the segments are uneven (insulation needs undercut) causing the brushes to bounce,,,,, ,,the brushes are worn,,,,, ,the brush hold down spring assemblys are stuck or corroded and the brushes arent being held down tight against the commutator AGAIN see below for the genny versus VR problem troubleshooting.....

TROUBLESHOOTING CHARGING SYSTEMS

ARE YOU SURE THE AMMETER IS WIRED CORRECT AND WORKS????? If you turn the lights or ignition on (if coil ignition not a mag) when she’s not running, the ammeter should swing over to the - discharge direction, does yours??? Are BOTH the ammeter terminals reading hot battery voltage?? They MUST !!!!! ! There’s but one wire on the ammeters Supply (from battery/starter) terminal while its other Load terminal wires to the BAT terminal on a Cutout relay or VR PLUS wires to feed loads like lights or ignition, unless where a 4 terminal VR is used where lights n ignition are fed from the LOAD terminal on the VR.

To Polarize the Generator, first temporarily dead ground the Gens Field post to case/frame, then momentarily flash jump a wire from the Cutout Relay or VR's "BAT" terminal over to its GEN (or ARM) terminal and you ought to get a small spark. Same things accomplished by momentarily flash jumping a hot wire (BAT terminal on Cutout Relay or VR or starter post etc) direct to the Gens ARM post to get the spark.

TROUBLESHOOTING A CHARGING PROBLEM IN CLASS A DELCO TYPE SYSTEMS

1) For a good working Gen to get to and charge the battery, it has to have a path usually from the Gens ARM post,,,,, ,,,,to and through the Cutout Relay (between its GEN and BAT terminals, regardless if on a VR or Relay),,,,, ,,,up to the Load (NOT to battery) side of the Ammeter,,,,, ,,,to and through the Ammeter,,,,, ,,,,from BAT side of Ammeter to ungrounded battery terminal, often via the starter lug post. Is yours wired that way or equivalent ??? The ammeter should read hot battery voltage on BOTH terminals, does yours??? Even if an ammeter were stuck (but still continuous) as RPM increases the battery voltage should rise from 12.6 to near 14 volts and/or the lights glow brighter (half that on 6 volt systems). Have you tried that in case the ammeter isn’t working right?????

2) If the above is so, the BAT terminal on the VR or Cutout Relay MUST ALWAYS READ HOT BATTERY VOLTAGE. Does yours??? If not, the Gen cant get to and charge the battery.

3) The Gen to VR (if it has one) wiring is as follows:

BAT on VR to ammeters load (NOT battery) side

ARM (or GEN) on VR to Gens Armature post.

FLD on VR to Gens Field post.

(L) Load (if you have a 4 wire VR) up to BAT supply input terminal on switch to feed loads like lights and ignition.

WIRING ON CUTOUT RELAYS: They wire BAT side to ammeters Load terminal,,,,, GEN side to gens Armature post. On cutout relay systems, the Gens Field post is wired to the light switch where it gets a dead ground for high charge or a resistive ground for low charge. Therefore, there must be a good connection from the Gens Field post up to the switch PLUS the switch is good and it’s well grounded !!!!! !!

4. THE GEN AND VR OR CUTOUT RELAY MUST BE WELL GROUNDED AND THE BELT GOOD N TIGHT. If any doubt, run a ground wire from the grounded battery post or clean solid frame member direct to the Gen and see what happens????? ????? ????? ????? ????

NOW, if the Gen and VR are grounded,,,,,all is wired correct,,,,, ,,BAT terminal on VR or Cutout Relay is HOT,,,,, ,,Belt is tight,,,,, ,,,Ammeter is good n continuous n works but she wont charge, have you had the batteries tested lately????? Is there electrolyte above all the plates and no cells have a gray or milky appearance????? A bad battery may not accept a charge you know!!!!! !! If the battery checks okay, proceed below to see if its a Gen or VR problem (AFTER you have insured the wiring per the above)

TO DETERMINE IF ITS A GEN OR VR OR CUTOUT RELAY PROBLEM

5. a) VOLTAGE REGULATOR SYSTEM: With the tractor running, temporarily ground the Gens Field post to case. If she charges then but NOT otherwise, the VR may be bad, or a wires missing from VR's Field post to the Field terminal on the VR, or the VR isn’t well grounded.

b) IF IT’S A CUTOUT RELAY SYSTEM and she charges only if you dead ground the Field but NOT otherwise, its either a bad switch or the switch isn’t well grounded or else the wires bad or open from the Gens Field post up to the switch. INSURE THAT GOOD SWITCH GROUND AND WIRING

6. If she still don’t charge, leave the Field grounded and jump a wire across from the VR or Cutout Relays BAT terminal over to its GEN terminal (jump by passes the cutout relay) and see if she charges. If then but not otherwise, a VR's cutout relay isn’t working correct (maybe points burned/carboned) or a Cutout Relays NOT working or not wired correct.

7. With the 2 steps above, you have basically by passed the VR or Cutout relays functions, so if she still don’t charge, you're left with a bad battery or wiring or the Gen itself.

8. MOTOR TEST. You can Motor test the Gen. If its grounded and you remove the belt and apply hot battery voltage direct to its ARM Post and have the Field Post dead grounded to frame, it should motor n run well (Armature n Brushes and Commutator likely okay). Then, if you next remove the Fields ground and it speeds up some, the Fields probably good. If it passes both those tests, it should charge, and if not, it may be a wiring or battery or grounding problem. The hot battery voltage may be taken off the VR's BAT terminal or the starter post or the battery itself for this test.

9. Typical Gen problems may be the brushes are worn down or the hold down spring assemblies are stuck/corroded/dirty and arent pushing the brushes tight down against the commutator. Check those things out. Worse may be bad fields or armature etc. Air and WD 40 etc can clean and free them, the hold downs must be free n snap and hold the brushes DOWN TIGHT and they cant be worn down too low.

SUMMARY: Check the wiring,,,,,the grounds,,,,, insure BAT on VR or Relay is hot,,,,, ,check battery (maybe load tested and Specific Gravity checked),,,,, ,,,good tight belt,,,,, ,insure ammeter is continuous (BOTH sides HOT),,,,, see if battery voltage rises above 12.6 (half that for 6 volt system) and/or light glow brighter,,,,, ,,,do the Field and cutout relay VR by pass checks,,,,, ,,insure the Gens brushes arent worn down and the hold down springs are free n clean and push the brushes down tight,,,,, ,,,,,check the connections,,,,, ,,,try the Gen Motor Test to see if its good.

You may just have a bad battery or bad ground or connection if the Gen and VR or relay are okay. Good Luck n God Bless, let us all know.

John T Nordhoff in Indiana, retired electrical engineer who usually lurks over on the Mother Deere pages instead of over here on the "dark side" lol

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MBU

03-28-2007 22:08:57




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 Re: Generator/voltage regulator problems. in reply to John T, 03-28-2007 04:42:24  
John,

I appreciate all the time you spent on your reply - that must have taken awhile!

I"ll test as per your instructions.

Thanks…

Mike



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Walt Davies

03-28-2007 09:39:49




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 Re: Generator/voltage regulator problems. in reply to John T, 03-28-2007 04:42:24  
HA! you forgot that maybe the needle is loose on the Amp gage.
Walt



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MBU

03-28-2007 13:33:35




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 Re: Generator/voltage regulator problems. in reply to Walt Davies, 03-28-2007 09:39:49  
Walt,

I wish! I bought a new meter and it does the same thing.



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Bus Driver

03-28-2007 04:41:18




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 Re: Generator/voltage regulator problems. in reply to MBU, 03-27-2007 21:57:46  
My suspicions would be the generator brushes, the regulator itself, and the grounding of the regulator mount.



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