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#390391 - 06/06/17 04:47 PM ammeter needle swinging wildly
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
The 6 volt original generator on my '32 is putting out just over 8 volts, headlights are steady, don't flicker, all seems normal but my ammeter gauge needle swings wildly back and forth from discharge to charge. Reads 0 at idle with no loads, but upon acceleration it goes crazy. Sometimes it settles around 10 amps but not for long.

Is the generator normally grounded through it's engine bracket starter motor and or through the fan belt adjustment arm that bolts to the timing cover ? If so, maybe that's my problem. The bracket on the engine block and the one on the timing cover have been freshly painted. Maybe the attachment points and bolts should be shiny metal ? Thanks guys.
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#390398 - 06/06/17 05:45 PM Re: ammeter needle swinging wildly [Re: hardaground]
Junkyard Dog Offline




Registered: 11/23/01
Posts: 28629
Loc: Eagle Point, Oregon
Polarize your generator and see if that corrects the problem. If not check the points on the cut-out to see if they are vibrating. Also, you could have a weak brush spring in the generator which would also cause the problem.

When you have that issue, have someone press down on each brush in the generator one at a time and see if that corrects the problem.

laugh wink beer2
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#390405 - 06/07/17 01:55 AM Re: ammeter needle swinging wildly [Re: Junkyard Dog]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
I polarized the generator. Cut-out points were cleaned up a little with carb cleaner and look secure. I couldn't ascertain if they were vibrating when running.
Anyway the needle stopped swinging, appeared to give proper readings but after a second or two, it returned to zero, unless I pulled the headlight switch and then she read discharge. With all loads off my voltmeter read only 6.42 at the generator when revving above idle. It was 8.4v approx before I went messing around tonight.
Maybe I solved one problem but caused another. Unknown how. I didn't check brush tension yet. Maybe the cut-out is kicking in and out erratically ?
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#390406 - 06/07/17 02:19 AM Re: ammeter needle swinging wildly [Re: hardaground]
Chipper Offline




Registered: 11/22/01
Posts: 16632
Loc: The Great State of TEXAS
The 6.4 volt reading suggests only minimal generator output if any. Might be just enough to close the cut-out points (or points closed when generator was polarized and not re-opened) so essentially you are reading battery voltage. Would definitely check the spring tension on the brushes and clean armature and maybe brushes. Also visually check to see if mica between armature segments might be a bit high.
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#390416 - 06/07/17 11:36 AM Re: ammeter needle swinging wildly [Re: hardaground]
m006840 Offline



Registered: 11/30/02
Posts: 4706
Loc: merrimack nh
I think you need to take another trip to N.H. to have your generator rebuilt and the cut-out checked or replaced.
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#390419 - 06/07/17 12:18 PM Re: ammeter needle swinging wildly [Re: m006840]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
If after a few more tests, I may just do that. bonk
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#390437 - 06/07/17 04:52 PM Re: ammeter needle swinging wildly [Re: Chipper]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
I re-traced my steps from last night. Re-polarized, poked around inside, brushes were firm, commutator felt smooth/shiny. Fired her up and the needle steadied out, no more looking like Dolly Pardon running a marathon. Gauge read normal, approx 14 amps underway, 8.5 v at high idle. I'm leaving it alone for now.

I did hear a hum like an angry hornet inside the cut-out last night when I was fiddling with the points.. Maybe its sticking ? There's a 20 amp in-line fuse in the batt wire further downstream under the dash. Once in a while it blows. Another mystery…..Anyway, I have no immediate things to break….errrr I mean fix right now. carbana
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#390439 - 06/07/17 05:41 PM Re: ammeter needle swinging wildly [Re: hardaground]
Junkyard Dog Offline




Registered: 11/23/01
Posts: 28629
Loc: Eagle Point, Oregon
14 amps is too high of an output. Adjust the third brush on the generator to bring the output down to 10 amps.

Sounds like re-polarizing the generator might have cured your ammeter problem.

The cut-out should not hum or buzz.

laugh wink beer2
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The Mangy Old Mutt

"If It's Not Junk.....It's Not Treasure!"

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#390440 - 06/07/17 05:44 PM Re: ammeter needle swinging wildly [Re: hardaground]
m006840 Offline



Registered: 11/30/02
Posts: 4706
Loc: merrimack nh
Does this mean you will be at Sturbridge this Saturday? Even though it seems to work OK right now from what you have described I would get the generator professionally rebuilt ASAP. Also you need to find out what causes the fuse to blow-sounds like a short happening somewhere-which will cause the ammeter needle to bounce. The 32 originally only had one 20 amp fuse on the light switch as far as I know so it would be good to know if/or why another has been added.
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#390460 - 06/08/17 12:03 AM Re: ammeter needle swinging wildly [Re: hardaground]
Chipper Offline




Registered: 11/22/01
Posts: 16632
Loc: The Great State of TEXAS
I suspect you didn't have a good contact on the cut-out points. A tiny bit of crud or loose wire can cause them to not contact or oscillate (causes the buzz).
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#390463 - 06/08/17 01:44 AM Re: ammeter needle swinging wildly [Re: m006840]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
I'll dial the 3rd brush back a bit but first want to see where the needle stays when on the open road. I can always turn on the headlights to bring it down if it stays at 14 amps.

There's a 20 amp in-line fuse between the starter post and the negative post of the ammeter. Maybe starting the engine with 12 volts 3 weeks ago weakened it, then it just blew. Slow blow fuse ?
The original 20 amp fuse is, like you said, on the lighting switch, post "B". Perhaps the prior owner felt if the genny cut-out points malfunctioned and closed during the night, the wires would overheat and melt since that circuit is always hot. I installed a battery cut-off switch when I fist bought the car and never leave it live unattended.

Yes, Sunday, not Sat. I intend to be at Sturbridge. C'mon down. That Olds guy Brito should be there too in his '31. laugh
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If it ain't broke…..fix it 'til it is.

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#390464 - 06/08/17 01:56 AM Re: ammeter needle swinging wildly [Re: Chipper]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
I suspect you're right. The points were dirty and the insulation is questionable on one internal wire.
_________________________
If it ain't broke…..fix it 'til it is.

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#391175 - 06/24/17 12:49 AM Re: ammeter needle swinging wildly [Re: hardaground]
hardaground Offline

Oil Can Mechanic

Registered: 11/02/14
Posts: 590
Loc: Connecticut
Does the use of a battery cut off switch require polarizing a 6v generator each time the cut-off is used ? The cut-off is on my ground (neg) battery post.

My needle decided to jump around again after I used the cut-off. It returned to normal after I again polarized the genny. Coincidence ?
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If it ain't broke…..fix it 'til it is.

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