ZW Issue Diagnosis?

After unplugging the ZW, remove the four screws that hold the top on and look inside.  There are carbon rollers that roll on the transformer windings tapping off the various voltages as you move the handles.  These rollers can wear out.  Or if the arm the rollers are attached to gets hot it can loose its spring.  If this is the problem, you need to fix it so as not to damage the transformer windings.  There are several threads on this site that explain how to change the carbon rollers. 

You should use external breakers or fuses on the ZW, not to exceed 10 amps under any circumstances, since the internal breakers are not reliable.  If the rollers overwear and the bracket cuts the windings, you have a real problem, so I suggest not using it until you've checked the innards.

RJR is correct, I would NOT use that until you check what is going on.  If you use the correct technique, you can replace the carbon rollers easily without disassembly other than taking the top cover off, I've done a bunch of them that way.

Thanks for the info everyone!  I pulled the cover off and took a couple pictures.
Haven't looked for the instructions on how to fix the rollers, but from what I can see, the brackets are not close to cutting the windings, but I'm no expert.

 

The outside handles' rollers don't roll - they slide.  The inside ones still roll.

 

Is there anything in here that I should be concerned about?

 

Thanks in advance, Dave

Are the rollers still round in appearence? If so they may just need cleaning and a small drop of lube at the rivot. If the rollers are pitted or really bad in shape they need to be replaced. You can use a sturdy diagonal cutting pliers to cut them off and cut the old rivot out, replace both the roller and rivot at the same time. Also clean the contact area on the inside of the ZW really good, do not use any spray can stuff as it may eat the varnish off the copper windings of the coils.

The rollers should be cheap enough to buy, around $1.00 to $2.00 each and $1.00 for two rivots. Most Lionel parts dealers have these in stock as they are a common item to go bad.

 

Lee Fritz

Do not move ha ndles.  Stuck rollers will da mage windings.  (Posted from smart phone)

If you go with external circuit breakers try to buy them from Mouser Electronics, very reasonable for prices. An 8 amp 50 to 75 volt breaker should do well for most needs with the postwar ZW. Put the breaker in series bewtween the terminal screw and the track on the A, B, C & D outputs.

The ZW's internal breaker is 15 amps and is wired in with the common terminal posts, so you would have to have a major short for the ZW's breaker to kick-in and interrupt power.

 

Lee Fritz

Looking at your photos, I offer do not use this ZW any longer.  I have four of them and each one has had all the carbon rollers replaced.  As Gunner points out, a simple task and parts are available from Jeff Kane, The Train Tender, NY....I buy a good deal of parts from him very reliable...Replace all four Carbon rollers and their pins. The external circuit breakers a are very good idea as well....

 

hope this helps...

 

JZ

The rollers are badly worn. They are easy to replace without further disassemble.

  Search and you will find threads about roller replacement.

 i would also clean the contact area on the coil. I would start with alcohol and use fine sandpaper lightly if necessary.  Don

Alcohol can dissolve the coatings on some "enameled" wire. While it might be fine on transformer coils, I wouldn't take the chance.

I suggest using odorless mineral spirits.

Slightly moisten a rag, and wipe the bare coils where the rollers make contact.

You need to check the spring pressure . When they heat up they lose there spring. In your pic you can see the it turned blue from the heat. Look at the other arms and compare the pressure, the one that is blue may have lost it's spring.    

your comment about

"Im no expert", concerns me.

I would give you the same advise

Calssic Toy Trains Magazine gives.

Live it to a qualified Electrician.

If you are not comfortable

and unsure, let the pros mess with it.

Some one trying to "fix" something electrical may end up with

a bigger mess than they bargained for.

Electricity is nothing to mess with.

My Dad was an electrician for 40 yrs and he taught us the

finer points of giving that field(no pun intended) the respect

it desreves.

I agree with Brad, I'd consider replacing the arms as well, those really look like they've gotten very hot!  You can see if they still offer plenty of pressure, similar to the inside arms, but they are certainly getting hot! 

 

Popi's comment deserves some consideration as well, this may be a case where you want to consider getting someone that is experienced in these repairs involved.

Absolutely correct!  Those arms must be replaced.  There has been very bad overheating. 

 

With all due respect, Popi, what makes you think that a qualified electrician would be qualified to take apart a ZW?  Wiring a structure is different from internally repairing an appliance.

 

For full protection for a ZW, all wires that go to the U post should be run through a single fuse or breaker, NTE 10 amp rating, as well as putting fuses or breakers in the A,B,C,D circuits.  Reason:  Say you have 8-amp fuses on each of these 4 circuits.  You could still have 32 amps flowing, which is a hazard, since the ZW shouldn't pass more than about 10 amps max.

Actually, I'd make the single breaker a 15A unit, as the ZW should be able to supply around 220W if it's in good condition.  At higher power outputs, the voltage out is only in the 16-17 volt range, hence the 15 amps for the common.  At 10 amps, you're limiting yourself to 160-170 watts total output.

John, I disagree with you on that. Maximum output voltage of a ZW is 20 volts. At 220 watts, you're pulling slightly over 10 amps. I take that as the maximum current that should be allowed through the windingsregardless of the voltage applied. I'm sure that you would agree with me that you can safely pull 30 amps from a ZW at a6 volt setting.

The maximum voltage of a ZW is 20 volts, that's with no load.  I've loaded one up to 8.9 amps using four 75W 8 ohm resistors, the measure voltage was 16.9 volts under load.  If I had another of the resistors, I could have probably gotten it to around 11 amps, and even if the unit maintained 17 volts output, the VA output is 187.

 

We'll have to agree to disagree on this point.  Remember, you don't want the breaker tripping before you get to at least 210-220 watts output, it's really there to provide protection for the transformer.

 

Actually, I would disagree.  I don't think you can NOT pull 30A from a PW-ZW under any reasonable condition safely.

The only reason I mentioned that is because my Dad was an

electrician AND CTT always refers such questions to the Pro's

and they emphasize that that is NOT a do it your self project.

 

Fires happen very easyly if you do not know for sure what you are doing.

better to be safe, than sorry.

I would recommend against putting any oil on the rollers.  There should be enough graphite in the carbon to adequate lubricate. The oil will just harden and may smoke or burn in the presents of the arcing there may be between the rollers and windings.  If the rollers do not turn freely, investigate for a mechanical problem.

I don't think you can NOT pull 30A from a PW-ZW under any reasonable condition safely.

 

Your double negatives are throwing me.  Together, they mean you think you can safely pull 30 amps from a PW-ZW.  Tain't so.

 

A PW-ZW is rated 275 watts (not continuously).  The faceplate max voltage is 20.  This works out to 13.75 amps.  Old Lionel recommendation was don't exceed 75% of this continuously.  That's 10.3 amp.  I submit that this is the maximum that the secondary windings can carry continuously without overheating.  If you set the output to 6 volts, that does not increase the carrying capacity of the secondary winding.  While the transformer itself may stay cool, the bit of secondary winding between the end and the roller will get overly hot if this is exceeded. 

 

Popi, I have wired up several homes n the family.  You'll have to excuse me if I lack the confidence in the "professional" electricians.  One of my sons bought a new townhouse from the builder.  A GFI in the kitchen was wired backwards, so it did not protect receptacles downstream.  A second son bought a used home.  We renovated the kitchen.  After being driven almost nuts, I found the electrician was feeding the kitchen outlets from each end of the string, from a different 20-amp breaker on the same side of the line.  A third son, whose hot tub I had 220-volt wired many years ago, had his house renovated.  The renovator's electrician altered the wiring to the hot tub, using thinner cable, and caused the motor to burn out.  I submit that the average electrician has no idea what's in a ZW.  Having done this task, it calls more for mechanical skill than electrical.

 

I agree with David re oiling the rollers.  Oil is generally an insulator, and his point about it carbonizing is well-taken.

I believe the ZW rating is 275 input,not output. With the inefficiency of the transformer I think at best you could get 220 out of it. At 20 volts that is maybe 11 amps. I fuse or breaker mine for 10 amps.

 

Not sure what to use on the rollers,maybe graphite very sparingly.

 

Dale H

Dale, in the 1940's & 50's Lionel produced a Bantam book "Model Railroading."  I still have a box with most of its pages loose (don't know if I have all the pages, or if they're all from the 1st or 2nd edition).  I recall that in it Lionel applied a 75% factor to the rated wattage for continual use.  That comes close to your calc.

 

Used books are availabe at:

http://www.ebay.com/sch/sis.ht...y+Train+Manual+1953+

Lionel+Bantam+Books+%23F1152

 

These rating are funny.  For years, I had only a single type R, 100 watts, from which I ran a #224 & a #736 locos, a #97 coal elevator, and a pair of 022 switches (4 bulbs at 5 watts each), and some lighted accessories.  The type R (which I still have) never comnplained, although clearly I was pulling at or above its rating.  I was very happy when my parents gave me a ZW one Christmas (it still powers a portion of my layout).

Are you guys talking about breakers on the individual outputs or a single breaker on the Common U terminal like the one inside the ZW?

I'm talking about the single breaker on the common, IMO it should be more than 10A.  Obviously, I'm in the minority, but I still believe that.

 

Breakers on the individual outputs should be sized to match the maximum expected load.

I think I should put a 15 amp breaker on the Common, but in reality I only have 10 amp breakers on the A and D outputs.  One ZW runs two loops that both have 2343 twin-motor trains, but no lighted cars.  One loop has a 5% grade.

I agree Dale, I'd never call on one output to deliver more than 10A, however the common is shared by all outputs, as you well know.

Thanks to all.  I'm not using the ZW until I, at a minimum, get new rollers installed.  Set of 4 on order.  The arm spring tension still seems very good - feels equal on all 4 arms...but not with any scientific quantification.

The color of those arms is troublesome.  With color like that it must have lost some tension, and I wonder if it would create a oxide film that would be resistance.

 

Frankly, Dale, I haven't put a breaker on the U circuits either.  Just lazy, I guess.

 

 

Well, the color is only at the top, if it has plenty of "bite", I suspect it'll be fine.  I'd be more concerned about really cleaning up the arm after removing the old roller so there is good contact between the roller rivet and the arm.

Those control arms are brittle. Lionel warned its service stations not to bend them.

When you go to replace the rollers, be certain to read the Lionel service manual pages. Look on page one of the linked document set for tips (item 6). These are instructions for a ZW-R, but the tip applies to any ZW.

 

http://pictures.olsenstoy.com/searchcd31.htm?itm=672

All IMO;clean the arms where they hold the rollers, Change the rollers , and clean where they contact the windings. Then test, My bet is this will fix it. Don

I think Gunrunner is right on with his talk

about breakers. I havent had trouble with any ZWs,

But I have seen cases and even fixed one were the breaker

would blow for no apparent reason.

I replced it with an electronic breaker I picked up at Radio shack.

 

You want to know how I tested the new breaker??????

You can't bend them an excessive amount, but I've done about a dozen PW-ZW roller replacements, and I've never had to take the arms out.  I also never broke one.  You can tell when you're getting too much tension on it.  You just need to get it far enough away from the windings to easily replace the rollers.

I believe that the material I referenced does not recommend removing the arms.

I don't remove the arms to replace rollers either.  

The thought is a good one, but in this case the pro the repair should be referred to would be a certified Lionel repairman (repairperson?  Stupid political correctness!), not an electrician.

If you do need contact arms, I have some. These are in good condition.

 

Gene

 

wheeler359@gmail.com

 

But I have seen cases and even fixed one were the breaker

would blow for no apparent reason.

 

Beats the more common alternative, not blowing.  An advantage of the external breakers is that they must be manually reset, rather than resetting themselves.

While I agree that such repairs are not for everyone, I think it's also a mistake to assign "God like" powers to someone just because he works in a repair shop.  I've gotten plenty of really bad repairs at factory authorized and trained repair shops, it's the way it works many times.

 

I think the replacement of the carbon rollers is well within the capabilities of folks that are handy with basic hand tools and is willing to ask for guidance.  Look at some of the very complicated layouts that are built and displayed here, there's a lot more places to have a fire in a large layout than rebuilding the transformer.

 

I think our mission should be to assist folks in such tasks and not try to convince them that it's over their head.

Seems like John & I agree again.  I know some people who need an electrician to screw in a light bulb (or think they need one), while others can look at any problem and quickly analyze and cure it.