Post war ZW Transformer

[Boscoed]

Hello. The ZW I'm using is nearly older than I at 63+. i had it serviced about 7 years ago. Ran great until tonight. I dedicated the B controller to my accessories. All was well then kaplooie. Everything went dark.  The remaining three controllers work fine.  Any ideas as to what happenned? What should I look to fix?  Thanks.

[lionelsoni]

Broken wire or wire connection, or broken carbon roller.  You can check the roller without opening the transformer.  When you turn the control slowly, you should be able to feel a subtle "notching" as an intact roller rolls over the exposed wires of the secondary winding.

[ADCX Rob]

The common failure is at the binding post.

[cwburfle]

As Rob wrote,, the common failure is the binding post, probably the "U" terminal. inside the transformer, all the "U" terminals are connected together. Try moving the "U" wire to the next terminal.

 

[ChiefEagles]

lionelsoni

Broken wire or wire connection, or broken carbon roller.  You can check the roller without opening the transformer.  When you turn the control slowly, you should be able to feel a subtle "notching" as an intact roller rolls over the exposed wires of the secondary winding.

Bob is probably right.  If you have used the handle continously, the roller over 7 years is probably warn.  If you leave the at a set voltage and have another off/on switch [as I do], then it is a wire.  I had one [I have several] that suddenly started dropping voltage afteer heating up.  Thought it was the coil breaking down.  Got a replacement coil.  As I was getting ready to replace the coil, found a solder joint that had suddenly gotten loose.  Resoldered it and all is fine.  Do a little exploring.

[Boscoed]

Wow, my first time using this Forum and the speed of replies is great.  Thanks for your help.  The roller seems fine, I do feel notching, so I'll open'er up and see what I can see. I hope it's obvious and something I can fix without setting my hair on fire. Thanks again Gents!

[cwburfle]

A ZW transformer will usually continue to work with a broken or worn out carbon roller. The holder drags across the coils.
That said, it is a very bad idea to use a transformer with defective rollers. Having the holder drag across the coils is going to cause damage over time. 

[gunrunnerjohn]

My vote is the wire on the binding post, I've seen a number of those cheap crimps fail.

[Boscoed]

Gents, well, I opened her up and discovered that the positive terminal (binding post) was broken and the lead had seperated. I'm now out to find a binding post that I can easily attach. It seems the original has some uique way of connecting the lead. I need a simple post that can accomodate a nut.

[papa3376]

Parts dealers carry repair binding posts.  Good luck.  George

[lionelsoni]

You can use an 8-32 machine screw with a ring lug inside the case under the head for the wire and a nut on the outside.

[TrainLarry]

The binding post was riveted in place. You can get the replacement part, T-159 and rivet it, or a T-159R that has a screw and nut to hold it in place for ease of replacement. Both available here.

Larry

[cwburfle]

I recommend the bolt-on post. I have both types on hand, as well as the tools to install them. I only use the rivet type posts on transformers that don't have the clearance for the nut.

I find that often the most difficult part of the repair is removing the old post. My best recommendation is to take your time, and work it out. The shaft inside the plate is sometimes distorted, making it hard to remove.

[ChiefEagles]

cwburfle

I recommend the bolt-on post. I have both types on hand, as well as the tools to install them. I only use the rivet type posts on transformers that don't have the clearance for the nut.

I find that often the most difficult part of the repair is removing the old post. My best recommendation is to take your time, and work it out. The shaft inside the plate is sometimes distorted, making it hard to remove.

Agree.  We use the same at "Miss Edna's" [Todd's].