Welcome! Please use the navigational links to explore our website.
PartsASAP LogoCompany Logo (800) 853-2651

Shop Now

   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver

Attention Forum Users: On the 28th of December 2023 at 9:00am Central Time, we will be taking the forums down for maintenance while we prepare the new forums for your use. Please click here for more information.

Tool Talk Discussion Forum

Mutli meters - generator troubleshooting

Welcome Guest, Log in or Register
Author 
AB

05-29-2007 21:18:53




Report to Moderator

Electrical novice here. I have rewired a 1952 vintage model 77 oliver gas and had the delco generator rebuilt at local shop. 6v positive ground system. New amp gauge, coil and VR also. I did polarize and got spark. I get a negative reading on amp gauge when I turn on the switch but after tractor starts I do not get a positive reading on the amp gauge. Do I need a meter to troubleshoot and if so can you recommend one? Thanks!

[Log in to Reply]   [No Email]
John T Correction

05-30-2007 11:16:43




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 05-29-2007 21:18:53  
OOPS Silly me, I missed the important word NOT in your post i.e. you mean shes NOT swinging over to Pos charge after she starts. This is wayyyyy y more then you need but it saves me a ton of time to copy n paste my entire Troubleshooting Procedure for non charging: Try the easy simple things first like a good tight belt and the grounds and connections all being good and then in Para. 5 it tells how to determine if non charging is a Voltage Regulator or a Generator problem. A cheap analog Volt/Ohm Meter can come in handy but a lot of the tests below ONLY requires a simple 6 and 12 volt DC test lamp.

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

[Log in to Reply]  [No Email]
AB

05-31-2007 00:40:19




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to John T Correction, 05-30-2007 11:16:43  
Thanks,
I used your procedure last week to polarize the genny. I guess I need a meter/test lamps. I was thinking the ampmeter wasn't working but if it goes to negative with the switch on I would assume it's OK? Now I'm thinking the genny or VR isn't right, even though I've had them rebuilt?



[Log in to Reply]  [No Email]
Gene-AL

05-30-2007 08:17:26




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 05-29-2007 21:18:53  
AB,
Is it possible that you have the Voltage Regulator output wire (Bat or L) connected to the wrong side of the Ammeter? There should be only one wire on the Ammeter side that connects to the tractor battery, usually at the starter or solenoid battery cable. The Ign Switch, light circuit (if any), and VR output should ALL be wired to the other connector on the Ammeter.

Your charging system may also be working correctly by charging direct into the battery without the current first passing through the Ammeter to give a 'Charge' indication. In this case, the Ammeter would always show a 'Discharge' whether the charging system is working or not.

If I have guessed right, based on your description, all you need to do is move the one wire coming from the VR from the battery side to the opposite side on the Ammeter.

If my guess is not right, then it sounds as if you need to carefully recheck your wiring and the charging components. An inexpensive analog (with a meter movement) Volt/Ohmmeter is usually sufficient for troubleshooting tractor electrical systems. The archives here are full of suggestions to diagnose trouble.

[Log in to Reply]  [No Email]
AB

06-01-2007 20:38:49




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to Gene-AL, 05-30-2007 08:17:26  
I moved the one wire to opposite side of ammeter like you suggested. I got a slight positive charge on the ammeter with switch on and tractor not running. With tractor running it did not make a difference. This is getting aggravating - thanks for trying to help.



[Log in to Reply]  [No Email]
Gene-AL

06-02-2007 11:31:14




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 06-01-2007 20:38:49  
AB,

Sorry, I may have misled you.

May I have one more shot at your problem?

You may have a 4-terminal voltage regulator with 3-terminals in a row on one side (L, Bat, F (or Fld), plus a 4th terminal (Gen) underneath on the base.

In this case, you should have these connections:

1. Gen on base of VR to A or Arm on generator.
2. F (or Fld) on VR to F on generator.
3. Bat on VR to Ammeter (one wire). The opposite connection on the Ammeter is wired only to the Starter switch (or Solenoid) which is also the battery (-) cable.
4. L (load) on VR, wire to Ignition switch, and to the lights fuse holder.

The voltage regulator must also have a 5th (grounding) connection from its metal base to the tractor mounting bolts in order to work. Some may have an all-metal base and mounting bracket combined which provides the ground. Others have rubber vibration-isolation mounts and MUST have a grounding strap (or wire) between the metal base of the voltage regulator and the bolts which mount the regulator on the tractor.

Might be worth a look...

[Log in to Reply]  [No Email]
Gerald J.

05-30-2007 08:03:42




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 05-29-2007 21:18:53  
Goose the engine speed. A generator doesn't charge at low speeds. Needs to run faster than that. It should intially show + on the ammeter and then if it has a voltage regulator it should taper down to zero after running a while if the voltage is right.

Gerald J.



[Log in to Reply]  [No Email]
AB

05-31-2007 00:27:30




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to Gerald J., 05-30-2007 08:03:42  
Ampmeter gauge does not respond to throttle/engine speed. That's what I'm trying to figure out - Ampmeter gauge responds to switch on in negative fashion but not in a positive when tractor is running.



[Log in to Reply]  [No Email]
John T

05-30-2007 04:49:08




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 05-29-2007 21:18:53  
AB, If it aint broke dont fix it as they say. I agree with CENTAUR. Assuming its a battery operated coil distributor ignition (NOT a Magneto)it should draw approximately 4 amps or so when you turn on the ignition switch which should (if all wired correct and points closed) be - discharge on the ammeter and if she starts up then shows + charge, SOUNDS OKAY TO ME.

John T



[Log in to Reply]  [No Email]
CENTAUR

05-29-2007 22:12:49




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to AB, 05-29-2007 21:18:53  
If you have a distributor and not magneto ignition you will get a negative draw indication on your ammeter while the points are in the closed position.If so put a insulator between the points and see if you still get a negative draw indication on your ampmeter. CENTAUR



[Log in to Reply]  [No Email]
AB

05-31-2007 00:29:39




Report to Moderator
 Re: Mutli meters - generator troubleshooting in reply to CENTAUR, 05-29-2007 22:12:49  
Yes, I understand the negative draw with the switch on/tractor not running. Trying to figure out why I don't get a positive charge when engine running.



[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:


TRACTOR PARTS TRACTOR MANUALS
We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home  |  Forums


Copyright © 1997-2023 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy