# ZW Transformer Repair



## limitwheel (Jan 8, 2011)

The secondary coil on my ZW transformer has a break in the winding. I can see that it's a clean break. 
My 1st question is, can I rewind the secondary coil using regular bare wire or does it have to be insulated?
2nd question is, The wire on my secondary coil has what appears to be a square cross section. Could I use round wire? 
3rd question Is this wire clear coated so as to insulate the wire? 
4th question is what would the wire gauge be, 12 or 10 gauge?


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## NIMT (Jan 6, 2011)

If you can see the break why not repair it? Just use a piece of kapton or polymide tape under the break and solder the break? 
Yes the wire is insulated. The square windings do effect the amout of windings, the workings, and the final ratio!


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## limitwheel (Jan 8, 2011)

Thanks for the quick reply,
I didn't think that repairing the break was possible. I figured that there would be more breaks coming. 
Would I just put that tape under the break and then solder the broken ends together?


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## NIMT (Jan 6, 2011)

I'm no transformer expert, but as long as clean off the ends, the kapton or polymide tape will help keep the heat away from the other windings and insulate the connection from the other wires. With the right soldering iron, flux, and solder you should be able to get a solid connection. 
Others on here might have a better repair Idea though.


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## T-Man (May 16, 2008)

There are only two ends. A break on the outer end is easy, you can unwind it a turn to get the slack needed to solder it. On the other hand if the inner lead breaks then unwinding a turn is not possible. Transformer wires are large normally smaller gage wires break. Be sure to scratch the wire clean of lacquer first.


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## gunrunnerjohn (Nov 10, 2010)

I'd fix the break, rewinding the core is not easy, hand winding will almost surely not work as well as it was done originally. I think the Kapton tape will do the trick just fine. If the windings get hot enough to melt solder, you have a more serious issue anyway! 

FWIW, I've hand wound a number of coils and a few transformers, it's very tedious work to get them to look decent. Yes, the wire is enamel insulated wire, it's most certainly not uninsulated!


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## servoguy (Jul 10, 2010)

The wire is insulated with enamel and the enamel in the area where the rollers ride is removed. Repairing the break is going to depend on where it is. If it is in the area where the rollers ride, you may have difficulty in making a repair that doesn't interfere with the operation of the rollers. Now I am wondering what caused the break.


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## NIMT (Jan 6, 2011)

limitwheel,
If you need some kapton or polymide tape just send a PM. I have a ton of both!


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## tjcruiser (Jan 10, 2010)

OK, guys ... you've intrigued me ...

What, exactly, are Kapton or Polymide tape??? Sounds like something diabolic out of a Superman movie!

I've never heard of those before ... clue me in on what they do, typical applications, etc.

Thanks,

TJ


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## gunrunnerjohn (Nov 10, 2010)

tjcruiser said:


> OK, guys ... you've intrigued me ...
> 
> What, exactly, are Kapton or Polymide tape??? Sounds like something diabolic out of a Superman movie!
> 
> ...


They're very thin tape that's very strong and has a high temperature adhesive. Used a lot in the aerospace industry.

Here you go TJ, right from the horse's mouth. 

Kapton Tapes



> Kapton Tapes are made from DuPont Kapton™ HN general purpose film with silicon adhesive. They have been used in applications at temperatures as low as -269°C (-452°F) and as high as 400°C (752°F). DuPont™ Kapton® polyimide films have set the industry standard for over 45 years in high performance, reliability and durability, with a unique combination of electrical, thermal, chemical and mechanical properties that withstand extreme temperature, vibration and other demanding environments. Kapton® polyimide films make innovative design solutions possible in a range of industries including consumer electronics, solar photovoltaic and wind energy, aerospace, automotive and industrial applications. Kapton Tapes have a high dielectric strength. Silicon adhesive protection leaves no residue. They conform to MIL-P-46112, TYPE I


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## tjcruiser (Jan 10, 2010)

Thanks John, guys ... cool (or should I say HOT) stuff. I've never seen that before. Duly noted.

Thanks,

TJ

===

Search hits:

high heat tape


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## gunrunnerjohn (Nov 10, 2010)

I've used this stuff for many years, it was a staple supply for aerospace electronics. Not much room, temperature extremes, and we needed reliable insulation. I use it now for when I have close quarters installing electronics into locomotives.


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## servoguy (Jul 10, 2010)

Sounds like it might be a good substitute for duct tape?


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## NIMT (Jan 6, 2011)

Kapton tape is a staple of decoder installs! I have rolls anywhere from 1/4" wide to 1" wide. It also makes an excellent straight line paint mask that leaves no residue behind! I also have nylon tape that is excellent for isolating rub points and making a quick slip bearing!


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## gunrunnerjohn (Nov 10, 2010)

Kapton tape and duct tape are totally different, and aren't really good substitutes for each other. Duct tape conforms to odd surfaces better. For instance, I'd never try to tape fiberglass ductwork with Kapton.  The nice thing about Kapton is it's very thin, so it doesn't take up a lot of extra space.

What I'd like to find is some of the Teflon tape we used to use for aerospace stuff for a reasonable price, that's another handy kind of tape to have around.


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## tjcruiser (Jan 10, 2010)

Just as a sidenote there, John, I woudn't recommend duct tape for any duct work. Sounds crazy, but the duct tape will surely degrade over time. Instead, I would recommend a metal foil tape made for duct applications. It'll last eons before any peeling or degradation.

TJ


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## gunrunnerjohn (Nov 10, 2010)

I actually do use the foil tape for the ducts, but duct tape was originally created for ductwork.


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## Big Ed (Jun 16, 2009)

gunrunnerjohn said:


> I actually do use the foil tape for the ducts, but duct tape was originally created for ductwork.



I was thinking the same thing.
Duct tape for duct work.

Evolution = foil tape.


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## gunrunnerjohn (Nov 10, 2010)

Foil tape for foil work?


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