No amps from mag post. Where to start?

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Model T Ford Forum: Forum 2017: No amps from mag post. Where to start?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Thursday, July 13, 2017 - 05:43 pm:

Finally got the family T 1920 started. 6v and it idles well. But, when we switch over to mag, it dies. We put a multimeter on the mag post while running and get NO amps on AC or DC.

I have no history on this engine, so have no idea if mag ever worked.

Where to start investigating or troubleshooting?

I've read about lint on the contact and no charge on the magnets, but don't want to start without a plan of action.

Motor and hogshead are in the car. There is a wire from the mag post to the dash area switch or amp meter, so I'm presuming it worked at one time in the last 95 years.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Thursday, July 13, 2017 - 06:29 pm:

Robert - I'd be the last one to give any advice on anything electrical, however, being as "electrically challenged" as I am, I'd do the really simple stuff like check for lint on the mag post, then I'd check for excessive crankshaft end play, and if those are okay, I'd then be looking for advice from those who are much less "electrically challenged" than me,....FWIW,.... Harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By john kuehn on Thursday, July 13, 2017 - 07:10 pm:

Remove the mag post and ck for any lint or any thing causing no contact between the post and the lead button on top of the mag ring.
It could also be no contact in the ignition switch.
With the engine off turn the key back and forth several times. It might clean off the contacts inside the switch plate to get a connection. Sometimes this will work.
Carefully ck the switch before ruling it out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Thursday, July 13, 2017 - 07:31 pm:

Robert you should be checking for ac voltage at the Magneto post voltage not amperage. Any DC voltage put to the Magneto post will neutralize your magnets


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, July 13, 2017 - 09:17 pm:

With the engine off and the wire off the mag post, take a resistance reading from the post to ground. it should be close to a direct ground. If it tests open, you have either a bad connection between the post and the magnet or the magneto windings are open. If you read an open, take the post off and make the same measurement from the button at the top of the magneto. If you get close to a direct ground, you might have discharged magnets. You can find other posts on the forum on how to re-charge the magneto in the car.

If you have excessive end play in the crankshaft, your magneto could be too far from the coils to give you a good working magneto, but even then, you should get some amount of AC voltage with the engine running fast.

Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Thursday, July 13, 2017 - 10:24 pm:

Great. Thanks for the starting point. I presumed, maybe incorrectly, that if we check voltage from the mag coil contact, that would eliminate any issues with wiring or key switch. If we get a reading at the contact, but when switching the key, the motor dies, I would suspect wiring/switch/ampmeter issues.

I'll be away from the T for the weekend and will jump on it on Monday.

Thanks for the starting point.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Wednesday, July 19, 2017 - 03:10 pm:

OK, with the engine off and the wire off the mag post, we connect one side of the multimeter to the post and one terminal to the negative battery terminal for ground. We get 2.37 ohms.

What does that mean? Do we have some open issues, or do we proceed with magnet charging?

Is there anything to remove or check on the underside of the post while the hogshead is still installed? Or, is any service to the mag parts inside the hogshead limited to removing the hogshead?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, July 19, 2017 - 03:25 pm:

You can remove the mag post while the hogshead is in place and check it for lint. You can also do an in-car magnet recharge without removing the hogshead. But you get a better charge with it off and charging each magnet individually (or in pairs). The very best charge is with the engine out, flywheel removed, and each magnet pole charged individually.

The third option is an opportunity to check for cracked/broken magnets that can lead to disaster.



Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Wednesday, July 19, 2017 - 04:08 pm:

Robert, you did not say if your multi-meter was digital or analog, with a dial and pointer needle.

Digital meters do not work well for measuring Magneto voltage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, July 19, 2017 - 04:11 pm:

Your test shows that the magneto is not open. It is either normal or it might be grounded somewhere in the ring. Next test with the wire off and the engine running, use an analog AC voltmeter and test for AC voltage from magneto post to ground. If you get voltage, try testing across a 12 volt light bulb with the bulb connected between magneto post and ground. You should get no less than 6 volts AC at idle and the voltage should increase with speed. It should get up near 30 volts AC at high speeds. If you get voltage but the voltage is low, you have either or both too much endplay in the crankshaft which moves the magnets away from the magneto coils or you need to recharge the magnets.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Wednesday, July 19, 2017 - 04:41 pm:

It is not the preferrred type, we understand that. But some readings are better than none. We are proceeding towards zapping magnets. Looking for jumper cables and/or battery cables to connect our three 12v batteries to do this.

We put our meter on the War Wagon prior to this and, got readings from 5 to 30 at various speeds on the meter, so we feel it can be used to get us operational. And then tweek coils and plugs and magneto down the road.

TO THE DRIVEWAY!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas Mullin on Wednesday, July 19, 2017 - 06:55 pm:

Robert, be careful that you follow one set of magnet recharging instructions, there are at least two different versions out there.

This image is from Murray Fahnstock

magnet recharge

Also, this link has more information: http://www.mtfca.com/discus/messages/50893/77160.html?1230876615


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dufault on Wednesday, July 19, 2017 - 07:20 pm:

Robert,

Regarding your statement:

It is not the preferrred type, we understand that. But some readings are better than none.

This is from a previous thread:

" By Warren Mortensen on Wednesday, May 09, 2007 - 06:06 am:
Best to use an analog meter when testing the mag unless you're using a high-end digital meter. Most of the digital meters I've seen are subject to RF interference from the ignition and the reading will be all over the place.

By John F. Regan on Wednesday, May 09, 2007 - 08:57 am:
Warren:
The problem you are talking about is NOT related to the cost of the meter per se. I have seen labratory grade meters do the same. It is just VERY IMPORTANT to use an ANALOG type meter when making measurements on a T when the engine is running. All readings using digital meters when engine is running is likely to produce jibborish.

By VRay on Wednesday, May 09, 2007 - 10:34 am:
John is right about the meters. I have both a Fluke and a $3 Harbor Freight digital. Both jump all over the place while my analog stays nice and steady. I think it is the meter response time, but I really do not know.

Starting a car on magneto can be frustrating. It took me a long time to learn how to do it. To keep the frustration and the tired arm to a minimum I usually switch to battery for hand cranking to start then switch to mag for running.

By Bob Cascisa in Poulsbo, WA on Wednesday, May 09, 2007 - 03:46 pm:
A great source for a GOOD analog meter is tBay. Many Simpson 260 and Triplett 630 analog multimeters go for $10 or less. These are great field use instruments.

Be_Zero_Be

By Chuck S. Lebeda on Wednesday, May 09, 2007 - 10:49 pm:
Fellows: I have a digital meter, that may be my problem in readings off the mag. QUESTION: This is a 1923 T and it does not have an Amp Meter next to the switch. Behind this blank is the dimmer resistane/dimmer circuit. In post 1178300562, Kenneth posted the wiring diagram; my T is not wired quite this way at this dimmer circuit. But the 'dimmer circuit' looks like a small coil of wires with three wires wired into it. It was covered with industrial goop. Does this circuit ever go bad? It appears to be a coil of wires (all rusty) about the size of a small spool of thread. Where can I get this type of 'dimmer resistance'? Ron, I am working on what you emailed, but may not get to it until weekend. Thanks, Chuck.

AND THIS IS MOST IMPORTANT:
By John F. Regan on Wednesday, May 09, 2007 - 10:53 pm:
Vray:
The problem is NOT the response time. The problem is that all digital meters have this circuit called "sample and hold" which takes a sample of the voltage, resistance, current...whatever and then holds it in a charged up capacitor while the digital circuit does a "successive approximation" to determine the value. All of this takes place many times per second but if there is any spikes of noise or "transients" as they are called, this process gets screwed up and the output is jibberish. Shielding helps and it WOULD be possible to design a digital meter for exactly this application but it really wouldn't tell you any more than a decent analog meter since one really doesn't need 1% accuracy to see if the varioius voltages in the T are OK for normal use.

Bob's recommendation is RIGHT ON.

The Triplett 600 series was a most prized Christmas present from my mom when I was 15 or so. It just blew me away to have such a fine measurement device for my ham radio projects. Alas mine got broken but I have another and still like it a ton. The Simpson 260 has been the work horse of almost every major company in the U.S. at one time or another. I suspect you will still find them in some company labs. Those clearly would be a great meter(s) to own.
Showing my age.

There is some very good information posted there - years ago -
Please do be careful "zapping the magnets" and pay attention to what Tom just posted. Your problems might get worse with a mis-step.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Thursday, July 20, 2017 - 09:36 am:

Well, they didn't get worse, but they didn't get any better. We do have an analog meter and get no amps from the post. We removed the post, no lint, the button and insulator appear in good shape. We reinstalled and get no volts from the post with engine running on battery. We used three 12v batteries fully charged and tried in two seperate procedures, one zapping two magnets 90 d apart and then testing and once just zapping one magnet and testing.
Still no volts on mag post with engine running at low and fast idele.

Appears we may have an issue that can only be determined and correct during the next engine removal.

A busy day yesterday, but not a very good nights sleep.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James Spadafore on Thursday, July 20, 2017 - 12:07 pm:

I didn't see it suggested yet, but have you tested the mag post itself? I had one that was grounding internally to its housing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 07:02 pm:

Are you sure you even have magnets installed? If you went by the directions and zapped it, then you should get something.
You need to hit it at least 3 times 90 degrees apart. make sure you pay attention to the compass each time when you set the engine. You are not charging one or two magnets, the zap is magnetizing all the magnets each time, but to get a stronger charge, you hit it 3 times 90 deg. apart so the other magnets are closer the the source.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eyssen - Abilene TX on Thursday, July 20, 2017 - 09:53 pm:

Do the Tom Carnegie charge. Horizontal magnet screws and hit it with the voltage. Easier than compass I am told.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Thursday, July 20, 2017 - 10:27 pm:

We did check continuity of the post while out of the car to make sure it was carry current. Did not put it back in and check for continuity from button to top of post. Something to check.

Are there magnets in the car? I don't know. Can I see or teel them from the hogshead, or do I need to remove the starter and feel them on the ring gear?

We zapped one magnet. Nothing
We zapped two magnets, 90 apart and nothing.

I was under the impression that using fully charged car batteries to do the zapping, the more I zapped, the less battery I was using and might actually start drawing down the charge. And, I would think if I got a volt or two, I would think I was on the right track and then fine tune the procedure to get at least 6 volts. I got absolutely nothing right now.

I'm taking the T to someone tomorrow that has forgottten more about T's than I'll ever learn and maybe he can shed some illumination on this.

I won't leave you hanging.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, July 20, 2017 - 10:59 pm:

You are not zapping the magnets, you are building electromagnetic field in the winding's on the coil ring. There is no zapping one or two magnets, the field is built up in the whole coil ring affecting all the magnets on the flywheel. If there is a break some place before the end of the coil ring there will be no place for the current to have a path to flow in so there will be no recharging of any magnets. If one of 16 the coils is grounded around the ring then only the magnets adjacent to the good winding's might get recharged, ex from the contact on the coil ring to which ever coil is grounded.
If those are the cases the whole exercise is moot, the magneto is for all intents and purposes, is dead.
One end of the coil ring is at the button at the top, the other is grounded to the coil ring frame which in turn is grounded to the engine/frame.
This will sound goofy but it is best to have the car pointed east/west esp if the magnets are weak. If pointed north/south the north pole magnet force will over ride the compass and can give a false reading. If the magnets are so weak as to not be able to generate current, not sure how you are finding the north and south poles of them? If there is enough magnetism and you are able to find north/south then there should be some out put how ever weak.

(Message edited by redmodelt on July 20, 2017)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, July 20, 2017 - 11:32 pm:

I expect your 1920 has a starter. It could be that at some time someone tried to pull the starter without first removing the Bendix. That can damage the coil ring and render the magneto dead, no matter how well charged the magnets are.

Yes, you should be able to see whether there are magnets. They're on the flywheel, in front of the ring gear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas Mullin on Friday, July 21, 2017 - 10:49 am:

Here's what the stationary field coils look like (courtesy of Martin Vowell)

field coil

And, here is the rotating part attached to the flywheel.

magnets

Matching the compass needle with one of the magnet poles is crucial to making this work.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Friday, July 21, 2017 - 05:55 pm:

Well, I promised an update, so here it is. Not good news for me. It appears that we were doing everything we could correctly, but there is a short ground in the circuit and, therefore, no way to charge the magnets. Everything that we could test and inspect from the inspection cover on the hogshead appears to be good and working, not not a complete circuit.

One guess was the external oiler may be shoring out on the mag post, but that was not the case. And, since at one point in time, this car had a 23v battery to help a poor starter or starting condition, it is a good possibility that someone pulled the starter out without removing the bendix first and there is where our isue lies.

In any event, it is a pull the engine problem and that will have to wait until winter when we have the time and space to do so. I'm making a list of other things to address at that time.

Thanks to all who took the time to help walk me through the process and terminology.

The War Wagon still runs and we've a few WWI memorial events lined up this fall from Ft. Benning, Camp Shelby, the WWI museum in KC and Ft. Riley. So, all is good in the T world.


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