Cold Solder Joint – Cyl 1 Coil

[John Gragg]

So I’m cleaning up my points and when I go to pull the set from cyl #1 I check the coil Primary and Secondary numbers. Primary is great, almost immediate zero.  Secondary bounced around several times on both sides, until I noticed the cold solder. I was getting readings in the 10s of millions and a TON of bouncing around.

Once I pushed hard on the solder joint everything settled down and I was getting good readings in the 9K range.

My question is: Aside from the plug wire lead, what type of connection is under that ugly solder joint? If I remove the solder, am I praying there is a lead coming from the coil or am I pretty sure there is something there, I just need to put down a better solder joint?

 

Pic Attached.

 

 

Thanks!

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12
57 Johnson RJE-19M
57 Johnson RDE-19

[aquasonic]

Hi John. These solder joints are hot solder joints and are common to the “horseshoe coils” from the 1940’s.

I suspect that the high resistance readings were likely caused by a little oxidation on the solder joint preventing a good connection to your ohm meter. When you pressed a little bit harder, you found that you did have a connection. It’s likely fine.

Under the solder joint is the coil button. The solder makes the connection from the button to the plug wire. I would not advise to disassemble the connection unless you need to put on new plug wires, but if you do use the heat of the solder gun to disassemble.

I have successfully soldered some of these connections, but the windings are very delicate, and too much heat from the solder gun can ruin the coil. My first attempt ended badly, but successive attempts have been successful.

Hopefully this helps, and you can go forward to the next thing to maintain.

 

[frankr]

I believe the term “cold solder joint” refers to a poor soldering operation familiar to electronic techs to mean not enough heat was used to provide proper flow of the molten solder, OR the joint was disturbed before the solder cooled.

John, I’d suggest simply re-soldering it properly.  Not much to lose.

I’ve wondered how the internal connection was made between the button and hair-thin coil wire, but don’t know the answer.

[seakaye12]

Are you getting appropriate resistance values from the spark plug end of the wire?  If so I personally would leave it alone.  I suck at soldering an would most surely ruin the coil.

[John Gragg]

I should have been more clear. The joint is loose and ugly. When I press my probe to it firmly, the joint moves. It has pock marks and a rough surface. In my experience, a good solder (like the one on my other coil) is smooth and shiny. This one is a prime example of either a cold solder or a dirty solder. Possibly a contaminated attempt at a solder or a ‘fix’. After my post I did more research a finally found a picture of what these coils looked like before they were connected to the plug wire. As aquasonic mentioned above, the ‘button’ is likely my issue. Since the solder moves, I’m assuming the button is damaged and moving as well. The reading fluctuated so badly I’m pretty sure this coil is toast. That said, I have a quality soldering iron and will be attempting a repair today. I will ask here, but will also start a new thread. Anyone have any experience with sourcing new plug wires?

P.S. just today realized using the ‘reply’ button notifies the respondent of my reply. Does it notify everyone who replied to me, or just the person that I used the reply button on?

Thx!

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12
57 Johnson RJE-19M
57 Johnson RDE-19

[aquasonic]

John, that coil may be fine. As Frank stated, it’s probably a bad solder job. I haven’t ever seen a coil button that moves, but who knows. Other not applying to much heat at the coil button, the other challenge is holding the wire steady enough until the hot liquid solder solidifies. Strip the end of the wire back the minimum amount to make the connection. Maybe 3/16″ or so. Use rosin core solder, with no flux. I tried flux with the rosin core, and it didn’t work for me. I believe the solder has the flux included.

Regarding plug wire, you need 7 MM copper core wire. I have purchased 100′ rolls for around $50.00, but I work on motors frequently. Not many auto supply places carry this wire anymore, but a few still do. Someone pointed out that it was available online from a lawnmower supply also. Ebay and Amazon should have smaller quantities available. Four feet should be plenty for your motor to do both wires.

[John Gragg]

So I, unfortunately, was correct. This coil is toast and someone has tried to make it work. I removed the solder very carefully and pulled the plug wire away from the coil. There was no wire coming from the coil, just a tiny pin hole where the ‘button’ should be. Used my magnifying glass to try to find something there, and no dice. Common sense says there needs to be an electrical lead coming out of the coil, so to test this I removed the solder from the good coil. Yes, inside of the solder ‘button’ is a wire coming out of the coil. Soldered it back in place and tested. Back to zero on Primary and 7.65K on the Secondary.

Went back to the problem coil and dug a little further, removing a bit more of the solder. Just a hole in the coil, no wire. Although this motor appears to be very much unmolested, someone has tried to effect a repair and missed the mark.

Luckily, I sourced a used coil last night and (I hope I didn’t get ripped off) two new replacement coils. An old post on this site gave me the superseded part number for the original number.  Don’t remember the original number, but the new number is 375189 (580084 comes to mind?). I guess these coils were put in a multitude of different motors of that era.

Aquasonic – Thanks for the reminder. No flux (flux equals acid, acid is bad). I have the rosin core solder, so all is well there!

Thanks!

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12
57 Johnson RJE-19M
57 Johnson RDE-19

[Mumbles]

I’ve dissected a few old coils in the past to see what makes them tick and have found there is usually a small braided wire going from the solder terminal to the end of the secondary winding wire.

The secondary wire is so fine you would need a powerful magnifying glass and hands of a surgeon to track it down. Then you would have to figure out how to remove the insulation in preparation for soldering without breaking it. This is why it was probably fitted with a braided lead during manufacture.

I think this is a Pal/Ranger style coil and you can see the braided lead going to ground.  The solder terminal has a similar lead.

 

1 user thanked author for this post.

John Gragg

[jeff-register]

Another way is to clip a straight pin in your meter lead & ground the other meter lead. See if you can get around a steady around 5000 ohms poking around the hi volt terminal. If you get good resistance try to solder a dab of  solder to the tab & recheck. Warning don’t over hear the connection & use a wet sponge to clean the tip of the soldering tip, then get a fresh drop of solder on the tip, then attach the connection using the top of the wire to heat from the wire down. That will keep the heat away from the coil. Just enough to melt & get off fast to cool the connection fast Your picture shows a braded wire also. Do the coil have 3 wires coming from the coil or 2 wires. Count the hi-voltage terminal also?

[John Gragg]

Hi Jeff,

Are you looking at the picture mumbles posted, cuz my pic does not show any braided wire, only the spark plug wire?

 

John Gragg
RIverside, CA

Just starting in the hobby, please be patient.

48 Sea King 5hp GG9014A
49 Sea King 5hp GG9014A
48 Johnson TD20
49 Johnson TD20
54 Johnson QD15
55 Johnson CD12
57 Johnson RJE-19M
57 Johnson RDE-19

[Author]

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