I have a postwar 275-watt ZW purchased from an estate sale and noticed that the A throttle is not giving any power.  Looking under the hood, the roller does need to be replaced but it is not down to the bare nub like some of the other rollers on the opposite end...yet those throttles produce the correct voltage.  

The "A" wire from the post seems well connected to the post and to the point where it is soldiered to the throttle gadgetry.  

Also, the plug does get warm after only having it plugged in for a few minutes and the prongs are hot to the touch.  While I have not noticed any cracks in the cord, I assume the plug needs to be replaced?

Any thoughts?

Greg

Original Post

if your plug is getting warm chanced are some of the wire strands are broken I would either change the whole cord or at least change  the plug with a new one then retry n plug in again  

certified MTH ASC tech and train repairs august 2019

repairs down to component level on all electronics

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For the lack of A output - check the A output against other "common" outputs on this ZW instead of against the "common" output in physical line with the A output. It is not uncommon that within the ZW the strip of metal connecting the 4 common outputs together becomes disconnected from individual "common" outputs.

MED posted:

For the lack of A output - check the A output against other "common" outputs on this ZW instead of against the "common" output in physical line with the A output. It is not uncommon that within the ZW the strip of metal connecting the 4 common outputs together becomes disconnected from individual "common" outputs.

This.  I've wound up repairing ZWs by removing the posts that have broken off the bus strip and replacing them with 4-40 bolts through the strip, held down with nuts on the outer case... 

GEDC1629

(note the nuts on the upper terminals) 

Mitch 

It's crackers to give a rozzer the dropsy in snide!

 

Remember, SCROUNGE!

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If the rollers are worn way down, STOP USING THE TRANSFORMER!  If you score the windings with the arm and short them, the transformer is trashed!  Replace the rollers, it's a pretty simple job and will preserve your investment.

Thanks for the helpful hints folks!  I found the issue after dissecting the transformer and discovered the "A" post wire to the throttle terminal had broken off.  I was able to solder it back on.

My next question...I noticed that the secondary coil has some "wiggle" room and hangs pretty close to the primary coil.  I vaguely remember someone telling me that it would be problematic if they touch etc...

So, I was able to stick a thin piece of plastic at the top of the metal "core" and underneath the secondary coil which raises it slightly.  (Pictures are attached).

I have not tried to operate it yet (because I am waiting on some parts to be delivered), but was wondering if what I did is safe?  

As always, thank you in advance for your wonderful insight!

Greg

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I would not operate it until everything is checked out. First thing I would do, besides replacing the rollers, is to replace the cord, even if it was replaced at some point it still likely needs to be replaced. I would also inspect the internal wiring, from the pictures that wiring is original, and some of them may be frayed or cracked and could cause a short. I love the ZW, but it is still quite old and things decay over time. 

The person who dies with the best toys dies a happy person

bigkid posted:

I would not operate it until everything is checked out. First thing I would do, besides replacing the rollers, is to replace the cord, even if it was replaced at some point it still likely needs to be replaced. I would also inspect the internal wiring, from the pictures that wiring is original, and some of them may be frayed or cracked and could cause a short. I love the ZW, but it is still quite old and things decay over time. 

Thank for the pointers.  I did replace the cord and will also install a modern circuit breaker.  All of the other wiring seems to be good shape.  Right now, my main concern is making sure the piece of plastic I installed beneath the secondary coil is safe and won't melt or cause harm to the unit.

Over the past two or three years I have probably repaired or renovated over 50 ZW transformers and have yet to come upon a situation where the clearance between the primary and secondary coil is an issue.

I totally agree with John in his above reply that you don’t want to operate the transformer with worn down or broken rollers. Having the roller arms alone against the secondary will give you the voltages, however in a short period of time the arm can scratch through the secondary coil insulation and cause a short circuit.   If and when this happens about all you can do is strip the ZW of reusable parts and put them in your parts bin. 

 Replacing the rollers is quite easy to do and can be done in just several minutes. If someone is not familiar with how to do it, the first thing they do is remove the roller arm,  grind off the head of the roller pin, remove the pin  and remove the roller.  Then they replace the roller and pin and figure out someway to peen over the bottom of the pin to secure it in place.   Then they reinstall the roller arm. Very, very time consuming. 

 Here is how I do it. First take a pair of needle nose pliers and crush the roller. The roller is made of an easily crushable material. Then I take a pair of diagonal wire cutters and snip the pin in the middle and then it is easy to remove.  Then install a new roller and pin and then take a pair of needle nose pliers and squeeze the bottom of the pin. The pin is hollow and it’s easy to squeeze and if you squeeze it flat it will never come out of the roller arm holder.

 You want to get all of the crushed roller and the old pins out of the bottom of the transformer so I tip it over and work them to one edge then turn it upside down and shake everything out.

Good luck on bringing your ZW back to life and if you have any questions that I can answer I will be happy to. My email is in my profile.

Jim

 

 

 

 

O Gauge Jim posted:

Over the past two or three years I have probably repaired or renovated over 50 ZW transformers and have yet to come upon a situation where the clearance between the primary and secondary coil is an issue.

I totally agree with John in his above reply that you don’t want to operate the transformer with worn down or broken rollers. Having the roller arms alone against the secondary will give you the voltages, however in a short period of time the arm can scratch through the secondary coil insulation and cause a short circuit.   If and when this happens about all you can do is strip the ZW of reusable parts and put them in your parts bin. 

 Replacing the rollers is quite easy to do and can be done in just several minutes. If someone is not familiar with how to do it, the first thing they do is remove the roller arm,  grind off the head of the roller pin, remove the pin  and remove the roller.  Then they replace the roller and pin and figure out someway to peen over the bottom of the pin to secure it in place.   Then they reinstall the roller arm. Very, very time consuming. 

 Here is how I do it. First take a pair of needle nose pliers and crush the roller. The roller is made of an easily crushable material. Then I take a pair of diagonal wire cutters and snip the pin in the middle and then it is easy to remove.  Then install a new roller and pin and then take a pair of needle nose pliers and squeeze the bottom of the pin. The pin is hollow and it’s easy to squeeze and if you squeeze it flat it will never come out of the roller arm holder.

 You want to get all of the crushed roller and the old pins out of the bottom of the transformer so I tip it over and work them to one edge then turn it upside down and shake everything out.

Good luck on bringing your ZW back to life and if you have any questions that I can answer I will be happy to. My email is in my profile.

Jim

 

 

 

 

 

bigkid posted:

I would not operate it until everything is checked out. First thing I would do, besides replacing the rollers, is to replace the cord, even if it was replaced at some point it still likely needs to be replaced. I would also inspect the internal wiring, from the pictures that wiring is original, and some of them may be frayed or cracked and could cause a short. I love the ZW, but it is still quite old and things decay over time. 

Thanks, I should have mentioned in my previous message that I did replace all of the rollers.  (You are correct in that it is easy which is why I probably overlooked it in the message. LOL)

I wanted to give an update on a succefully finished project!  I installed a new plug and rollers, got all of the components to the transformer back to their correct spots, added a fast-acting circuit breaker and screwed the top back on.

Each post produces the correct voltage and the circuit breaker trips within 2 seconds!

Thank you to everyone who gave me advice and pointers on how to get the "beast" working properly again!

Greg

Totally agree...I'm planning to use the ZW to power a tradional "vintage" postwar layout.  While I thoroughly enjoy my TMCC/Legacy layout, there is just something about being able to operate a function or task at the flip of a switch...not having to memorize numbers or the pattern of keys to press to uncouple or turn on a block etc.  I'll go to this layout when I am yearning for a "simpler" time LOL!

Gregcz1 posted:

Totally agree...I'm planning to use the ZW to power a tradional "vintage" postwar layout.  While I thoroughly enjoy my TMCC/Legacy layout, there is just something about being able to operate a function or task at the flip of a switch...not having to memorize numbers or the pattern of keys to press to uncouple or turn on a block etc.  I'll go to this layout when I am yearning for a "simpler" time LOL!

With postwar equipment and mechanical E-units that breaker will be fine.

Santa Fe, All the Way

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