My PW ZW measures 5v off of the 3rd from the left “U” (COMMON) terminal when connected to ANY of the A-D terminals, with all throttle controls in the OFF position. My measurements are below in volts:
.All Throttles OFF
A B C D
U1 0 0 0 0
U2 0 0 0 0
U3 5 5 5 5
U4 0 0 0 0
A Throttle Maxed B Throttle Maxed
A B C D A B C D
U1 20 20 20 20 0 0 0 0
U2 0 0 0 0 20 20 20 20
U3 5 5 5 5 5 5 5 5
U4 0 0 0 0 0 0 0
I think there’s been some serious rewiring done inside your transformer. Notice that in your tables above A, B, C, and D always have the same voltage. I think this means that the roles of the A-to-D terminals have been swapped with the U terminals, which are the only ones that should be connected together internally.
How the 5 volts is getting on the U terminal (that I think should really be the C) is not clear to me. It’s not coming directly from the 8-volt fixed secondary winding. When you move the C handle slightly, does it not jump from 5 directly to 8 volts? That and the fact that it goes up to 20 volts when you turn it all the way on would suggest that some resistor(s) or lamp(s) is connecting it to some source, perhaps something in the pilot-light circuit, or added components. Someone may have wanted a voltage that would not go to zero, to keep an e-unit from stepping.
I think a look inside is in order.
The U terminals should all be joined together inside by a copper strip. Any U terminal not joined to the copper strip may have fallen off or has been removed & re-wired. A & B power supply wires should by on one side and C & D wires on the other side.
Like Bob N. mentioned I too think that somebody rewired your ZW. What about voltage from other U terminals to U 3, the one that you get 5 volts to any A thru D terminal?
This may not be your problem but I will throw this in. A couple of common ailments that I have found on postwar ZW’s is for one of the A thru D wires coming off inside the transformer at the terminal hookup point. The second most common problem with the ZW is from age & use, the roller wheels inside get flat or are pitted and won’t allow full voltage to get thru.
While inside with the lid off and power plug removed from the wall, clean the area that the roller wheels make contact with.
Lee F.
“While inside with the lid off and power plug removed from the wall, clean the area that the roller wheels make contact with.”
What would you use to clean the windings? I am always concerned about causing damage there.
lionelsoni - I checked the C-U3 connection, and as you stated, with a slight movement of the C handle, the voltage jumps from 5 to 8v.
There was also a question posed by phillyreading as to power measured across the other 3 COMMON to U3. U1-U3, U2-U3, & U4-U3 showed no voltage.
Ques #1 - Assuming that the Lionel repair guy does not have your collective insight, what should I tell him is my problem…C throttle won’t close?, check U terminals internal connections to each other?, Would that be enough (or correct)?
Ques #2 - If I were to use the ZW “as is”, but only use A-U1, B-U2, & D-U4 as separate power sources, what would be the downside?
Thanks again for the help!
I would ask him to rewire the transformer according to the Lionel schematic.
Without knowing exactly how the transformer has been rewired, I couldn’t say.
Pull the cover off and look to see if the roller is returning to the off position, its possible that the shaft has slip. I 've repaired a couple off zw’s that had this problem.
Bill
I mis read your post, I believe You have a wiring problem.
Bill
Take your readings again, this time with a load.
It sounds like there is a rivet or stray wire strand catching the “C” arm or ring/lug inside the case.
It would be a mounumental task to re-wire the “U” posts of a ZW, especially the “B” & “C” terminals. A quick visual inspection should dispel that theory.
Rob
Here’s a link that may be of some help to you.
http://www.tranz4mr.com/site/ZW_Page/ZW_Page.html
check it out
JoeJ
Rob, he says the transformer doesn’t like having the U terminals connected together. If it hasn’t been rewired, then it must be either that he has mis-identified the two rows of terminals somehow or that someone has re-labeled them so cunningly that he didn’t notice. As I said, it’s time to look inside.
It appears that the owner of this transformer may have his post labeling confused. I notice that when the “A” throttle is maxed, he lists the U1 terminal at 20 volts across a,b,c,d, It appears that what he is calling the "U1’ terminal is actually the “A” terminal. What he is calling the A,B,C,D terminals are actually the common “U” terminals. And so on.
The A through D terminals are on the bottom row, closest to the base of the transformer. The four “U” terminals are closest to the top. Technically, it would be possible to rebuild a ZW with the “U” posts across the bottom, but it would be a lot of work. I cannot imagine why someone would do it.
My guess on the five volt minimum on the “U3” (probably the “C” terminal) is the wiper arm is out of alignment, and won’t go to the off position.
I recommend having someone who is familar with the innards of a ZW look at it.
By the way, if you connect the hot terminals together, and set the output to different voltages, you will have a dead short with no circuit breaker to protect the transformer. It wouldn’t take long to ruin the transformer doing that.
My firm belief too.
Rob
Well, first of all thanks to lionelsoni, phillyreading, boxcarbill, joey1575, ADCXRob, & cwburfle for your comments. Although I searched the CTT archives & other sites (Olesenstoys,etc) before I ever made my original post about the ZW, I SCREWED UP BIG TIME! While my original measurements were made correctly (and yes lionelsoni, I know where the common posts & A-D are located on the ZW), I accidently transposed the voltage measurements betwwen common & A-D when I placed the data in my post. After several suggestions to my original post, I rechecked the voltage measurements, but still did not catch the transposition error. Again my apologies.
With reluctance, I “opened-up” the ZW tonight, mainly because you guys all seemed to think that this was the right thing to do. When I did, I found that the wiper arm for throttle C does not clear the copper windings when in the OFF position (like the other 3 throttles do). Is this something I could adjust or should I have the Lionel repair guy do it? Tom Bell - Zephryx
I doubt the wiper-misalignment hypothesis. The voltage that he sees at the bottom of the scale is 5 volts, whereas the voltage on the variable winding ranges from 8 to 20 volts. There is no wiper position that could get 5 volts off that winding. He also reported, in response to my suggestion, that the voltage jumped abruptly from 5 to 8 volts as he started to move the handle. All of that is consistent with a wiper in the right place but connected to some compliant source of 5 volts. When the wiper falls off the low end of the variable winding, you see 5 volts; but everywhere else you see the normal voltage from the low-impedance variable winding.
Whether the posts have been swapped, relabeled, or mis-identified, the result is the same. All three possibilities seem individually unlikely: Swapping is a lot of work, though not as herculean as it could be. Relabeling is difficult to do without leaving evidence. And mis-identification seems implausible given the clarity of the original markings. But I think one of these must have happened.
Here’s why I’m not so skeptical about terminal swapping: My type-Z transformers have the identical T-159 terminals, several of which have come loose. The repair is easy. I just put an 8-32 screw into the hole from inside the case and a nut on the outside. I can imagine someone who has had some terminal failures giving up on the T-159s, going wholesale to screws, and swapping the rows accidentally when unable to see the labels from the inside of the case, or deliberately to make his outside wiring neater.
Well, I’m still puzzled about two things. You said, “When I loop wires to connect the COMMON from post-to-post, then turning on ANY throttle causes the ZW to hum loudly.” This doesn’t seem to be explained by a data mix-up. Is this still true?
And I am surprised that you are getting that 5 volts. I could understand a consistent 8 volts at the bottom of the scale; but 5 seems to require only the very slightest touching between the roller and the winding, or perhaps some conductive carbon dust nearby. Is that 5 volts always there at the lowest position? And is it always the same voltage?
(My previous post was written before I read the one above it. I’m having a really hard time posting anything on this forum this evening.)
It’s always a good idea to have a newly acquired used transformer checked out before using.
That said, I think you should ask yourself how you are going to use the transformer. Many folks either don’t use the inner control dials at all (B and C), or use them for accessories / lighting. In those cases, there isn’t a need to turn the power off, and you can leave the transformer alone.
Fixing this problem is probably going to entail quite a bit of dis-assembly of the controls on the “C” side.
When the subject of Lionel transformers come up, I always like to mention that the internal circuit breaker does not do a very good job of protecting the transformer, or anything else. As I posted earlier, it only protects circuits running through the common terminals. If you accidentally create a circuit between any two of the “hot” posts (a,b,c,d), it is unprotected. Also, the breaker is slow to trip, and it can take a lot of power. Enough to melt insulation, and to generate enough heat to burn fingers and such. So I always recommend putting an external breaker on every “hot” post. I use postwar Lionel #91 adjustable magnetic circuit breakers. When properly adjusted, they trip instantly. Lionel also made a #92 non-adjustable bi-metalic circuit breaker. They trip much faster, and must be manually reset. Not as good as a #91, but better than nothing. Some folks use fuses or breakers purchased from electronic supply houses.
Lionsoni - I rewired loops of wire connecting the 4 COMMON terminals & they worked fine with any of the throttles on, so I must have used the A-D terminals the first time! Another screw up (maybe now you can understand why I was reluctant to open up the ZW). The Commons appear adequately connected to each other internally with a copper strip, & when I repeated the measurements that I originally posted, results were the same as before (excluding my transposition error). The 5v is a repeatalble 5v on my multi-meter and always availabe from the C terminal.
Also, this ZW was bought new by my Dad, and I only know of it going in for repairs once, and that was to repair the C throttle which had stopped working. The ZW worked fine after that, but was always used for Christmas layouts & then stored for the rest of the year. We never used a voltmeter back then, but I never suspected any problems with the C throttle.
So my “final” questions again:
#1 - If you believe me that the C wiper does not clear the windings in the OFF position (the other 3 throttles clear the windings & contact a vertical metal strip), could I adjust that myself without a special tool?
#2 - Given that I intend to use the ZW for accessories (turnouts, UCS’s, lights, etc.), again what is the downside to using A-U1, B-U2, D-U4 as separate power sources & just leave C-U3 alone?
Thanks for everyone’s help. I tried to make my original post as accurate as possible, but your collective responses showed my errors & even got me to take the cover off of the ZW.
Tom Bell - Zephryx
Tom
If the handle has slipped, its more likely to have slipped on the outside between the dial and the shaft. This would require removal to fix. If you live close to Norwalk Oh. I can help.
Bill
You say that the wipers “clear the windings & contact a vertical metal strip” in the off position. This doesn’t seem right. They should be on the metal strip in the fully-on position. Here is what the transformer itself looks like:
The metal strip on the left should be fully on (20 volts). The off position should be off the winding and resting on the plastic area on the right. Take another look and see whether that isn’t how yours works.