[AT] EVENING UPDATE

Mon May 11 20:30:40 PDT 2020

OK, here is what I’ve seen on the magneto for my Cub. There should be a small reading from the coil wire to the magneto case when connected to the screw. I’ve read that it’s correct, but don’t quite understand why since this would indicate a grounded circuit to me. I believe it has something to do with the points and condenser that are also attached to the screw and there is a bleed circuit that doesn’t affect normal operation.  I’ve measured from the screw to the case with everything disconnected and there is no continuity, it only shows up when everything is connected.

As far as no continuity between the coil wire and the center contact, there should be a reading This is nothing more than a very long wire wound around a metal core. No reading would indicate an open circuit which means there’s a break in the circuit. Now the break could be in the coil itself. OR....

The wire from the screw is disconnected from the coil itself, which you may be able to fix with a little solder. OR...

There is a break in the wire itself, which again you should be able to fix.

Take a probe from your meter and push it into the wire right at the point were it enters the coil. Measure from there to the end of the pigtail wire. Continuity means good wire. No continuity means break in the wire, or your not making good contact were you inserted the probe. You may want to strip a little insulation off of the wire at the coil to ensure you get a good contact. You can always patch it with some heat shrink or RTV. Also, you may be able to see the solder joint where the pigtail connects to the coil. If so put the probe there.

Next check from were you inserted the probe to the center contact. No continuity means a break in the coil, which is not repairable, or the pigtail wire is disconnected from the coil. You may be able to peel back some of the coil insulation to get to where the wire attaches, and if disconnected, resolder it. You won’t damage the coil as long as you don’t knick any of the coil wire. If you have to pull a little of the coil wire out to solder, that’s OK, just carefully scrape the varnish off of the wire before you solder.

One more thing would be that the center contact is not connected to the other end of the coil, but I would doubt that since it’s essentially molded into the coil body and I don’t see how it would become disconnected without the coil  possibly being severely mishandled or dropped.

I realize that my magneto and your magneto are slightly different designs, but their basic operation should be the same.

Good luck.

Carl
----- Original Message -----
From: STEVE ALLEN <steveallen855 at centurytel.net>
To: at at lists.antique-tractor.com
Sent: Mon, 11 May 2020 22:32:58 -0400 (EDT)
Subject: Re: [AT] EVENING UPDATE

OK, gents:  here is what I found tonight:

The condenser has NO continuity between its case and the terminal.  With the wires removed from the screw terminal on the points, the two parts of the points have NO continuity between them.  

For those familiar with WICO X mags, the points are connected together by a screw that holds the spring for the moving point in an insulated block on the frame of the lower, non-moving point.  Two wires are attached to that screw.  One comes from the condenser; the other comes out of the coil.  THAT wire in my mag has continuity with the case of the mag.  There is NO continuity between it and the center contact on the coil itself.  

If the condenser is bad, continuity between its center terminal and its case is NOT the failure mode.  

The points have continuity between them when open ONLY when the wire from the coil is attached to them.

That's all I know new tonight.

The "original" Steve Allen

----- Original Message -----
From: STEVE ALLEN <steveallen855 at centurytel.net>
To: at at lists.antique-tractor.com
Sent: Mon, 11 May 2020 17:39:06 -0400 (EDT)
Subject: Re: AT Digest, Vol 28, Issue 7

----- Original Message -----
Message: 7
Date: Sun, 10 May 2020 19:53:23 -0500
From: Phil Auten <pga2 at basicisp.net>
To: at at lists.antique-tractor.com
Subject: Re: [AT] Project Updates '49 A, '51 A, and '47 B (STEVE
	ALLEN)
Message-ID: <168f1f90-8d7a-1eef-e95e-28fb0fa7e41b at basicisp.net>
Content-Type: text/plain; charset=utf-8; format=flowed

'49A - If your points are clean and reading .5 ohms when closed and .7 
ohms with cardboard separating the points, your points are shorted. With 
the cardboard in, they should read an open circuit, and .5 ohms when 
closed says your contacts aren't making contact well. If you took those 
measurements with the points installed, disconnect them and retest. If 
the points read 0.0 ohms closed and open circuit with the cardboard in, 
then the problem is elsewhere.
'49 A: I forgot to mention, if the points measure correctly outside the 
distributor you may have a bad coil.

Phil in TX

Phil,

Remember that the points set in a Wico X mag is two separate pieces.  If I take them off, I can screw them back together and check for continuity, BUT:  while mounted in the mag,
the fixed one is in contact with the case of the mag, and the other, the one that moves, is in contact with the terminal of the condenser.  Now, let me speculate here:  
the terminal in the condenser does not touch the case of the condenser, right?  So, the two points should not have continuity because the one is connected to the terminal 
and the other is "connected" (through the case) to the mag case.  UNLESS there is continuity inside the condenser.  I do not understand condensers well at all, 
but *SHOULD there be continuity between the case of the condenser and the terminal of the condenser*?  
If not, that may well be my problem (per Cecil).  I will investigate tonight.

BTW, I know that the shaft is turning and that the points are opening and closing:  I have verified that much by turning the crank.

The "original" Steve Allen
Who is avoiding the local Menards

_______________________________________________
AT mailing list
AT at lists.antique-tractor.com
http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com