This is my first post here so please bear with me! I have just started to try to get my father's Lionel trains, mostly postwar and a few prewar items, working again to be ready to share with my son who is almost old enough to appreciate them as I did when I was a child. (In those days they were stored at my grandparents' house a continent away from my house so I only saw them once a year!) I am starting with the ZW transformer and 671 loco with 2046W tender.
So far I have successfully replaced the crumbling power cord and two worn rollers on the transformer. I only have a cheap digital ammeter/voltmeter so I am unable to make very accurate measurements. Also the loco isn't working yet so I can't test it loaded, though I have got the whistle cleaned and working.
I think probably both of the rectifiers are shot. When I engage the whistle switch the relay clicks on enough to kick the motor and sound the whistle, and then immediately comes off again until I release the switch. On both sides (A-U and D-U) I get correct variable AC voltage close to the marked amount when the lever is engaged and the whistle switch is off. When I turn the whistle switch on I get a continuous additional 5V from the compensating coil as expected. However, I don't see the DC component at least on my meter. I see a spike as I move the whistle switch on or off, then it returns to ~0. This corresponds to the whistle's behavior of course. Is that what you would expect to see if the rectifiers were both non-functioning? Is there any option I should try other than replacing them? I am hesitant to take the lever assembly apart but I guess I will have to if I need to replace the rectifiers. On both sides, also, if I push the whistle switch all the way to the end of its travel then I lose power, I assume as the contacts 'fall off' their seats. Is that expected, or is that something I could probably adjust and fix if have to take the whole thing apart anyway?
The other unexpected behavior is that I see leakage between the A-U and D-U circuits. What I mean by that is that A-U full on gives 20V, A-U nearly off gives 6-7V, then fully off (roller off the coil) the voltage jumps up, and becomes proportional to the position of the D-U lever. With D-U fully on, A-U in 'off' gets around 15V, going down to 4.5V with D-U fully off. The same is seen on the D-U side. However, when I measure the resistance across A-U I see 1MOhm when it's off (independent of the measured voltage), dropping down to a few Ohm (variable) when it's on the coil. This is all being measured with no load on the transformer. I don't remember my high school electrical engineering very well; given the high resistance when the lever is off, should I just not worry about the phantom voltage?
Thanks!
Michael.
I suspect that the "phantom voltage" problem has to do with your digital meter. They have very high input impledance, which allows them to measure voltage capacitively coupled into an "off" transformer circuit. You should be able to get a more useful voltage measurement with a load on the "off" circuit. Practically any incandescent lamp will do. An actual locomotive will for sure.
Something similar may be happening with your whistle control. It is designed to deliver a full half-wave voltage when you first move the control. This gives a strong DC component to pick up the whistle relay. Then, as you move the control farther, it shunts the rectifier with a low resistance, intended to restore much of the AC. But when there is no locomotive load, the DC component from the rectifier can be substantially attenuated. Get your locomotive working and try it with the locomotive and the tender on the track.
Bob Nelson
Thanks very much for the quick reply! It sounds as if I was being too impatient :) I will wait until I get the locomotive working and hope it just works; and then report back either way.
I was able to get the 671 loco running last night, and as you suggested the transformer seems to be working fine: no operational problem with leakage, and the whistle stays on. The E unit is sticking though, so back to maintenance. Thanks again.
I'm glad to hear your ZW is working!
E-units often have that problem, which many attribute to a magnetized magnetic circuit. I doubt that is the cause, because the AC solenoid current makes the e-unit into a virtual de-magnetizing machine.
My experience is that the pawl wears notches into the crotches between the ratchet teeth, which then prevent the pall from falling when the solenoid is shut off. If you can see or feel the notches, you can probably remove them with a moderate shaving of the plastic teeth with a sharp knife.
I had a chance to open it up and take a good look last night and couldn't see any notches etc. The pawl almost never sticks in the 'up' position. The problem is that it takes a lot of power to lift up. Below 12-14V, the motor keeps running in the same direction but above that the pawl finally lifts and turns the ratchet. Because I was testing with the unloaded locomotive, I wasn't hitting enough voltage. As I turn the power up and down enough to run at a reasonable speed it just stays in the same direction. But if I 'surge' the power full on, it does reliably stop, then restarts in the opposite direction. Maybe this is another problem of 'unit testing' without a full train, and I won't have an issue in practice because I will be using more power.
What is the expected voltage at which the pawl will lift? The mechanism doesn't feel at all stiff when the e unit is removed from the locomotive. When I squeeze the sides it gets a little harder to turn, and when screwed in there is a bit more resistance, but it's pretty easy to lift with a small tweezer stuck in. I lubricated the ends of the wheel axle a little and it seems to have helped marginally.
I’d agree about the E-Unit, the teeth on the drum often do get notched. Personally, I’m more inclined to a file to remove these notches, but to each their own. I also like to thoroughly clean the solenoid, to make sure that it has as little resistance as possible. I don’t think I’ve owned a single lionel loco with a mechanical reverse unit that worked properly when I got it. Generally, giving the shaft of the solenoid inside and out a thorough cleaning will send you in the right direction. I have on a few occasions lightly oiled the surfaces of a particularly sticky E-Unit mechanism, but this was only a temporary measure to help the unit loosen up, and I don’t reccomend the practice, as it can and will attract dust, and once some dust gets stuck to the oil, the unit will start acting up again.
"Unless bought from a known and trusted dealer who can vouch otherwise, assume every train for sale requires servicing before use"
It sounds like a sticky e-unit to me. You should be able to cycle the e-unit at a voltage low enough that the locomotive, even with no cars attached, doesn't move or is just barely moving on the track. Certainly, the e-unit should be working at 12-14 volts when you push the Direction lever on the ZW. Since you've already lubed the ends of the e-unit drum you may want to consider cleaning the solenoid itself. You might try using electronic contact cleaner, or, if you're brave enough you can pry the e-unit apart and give everything a good scrubbing. They're a bit tricky, but you sound talented enough to handle the job, and there are a couple of "how-to's" on YouTube to guide you through it. Bad comes to worse, there are electronic replacements available, but then you don't get that sweet "hum" that many of us still enjoy. Good luck!
I'm feeling pleased with myself now. After disassembling and reassembling the unit a few times getting no closer to understanding the problem, I finally noticed that the plastic body of the coil is cracked, leaving the coil at a slight angle off vertical which was why the pawl wasn't moving smoothly. I discovered that pushing against the side of the coil to close the crack helped, so I stuffed a couple of wedges of plastic between the coil and the housing, and now it's reliably switching at low voltage!
Lionel specified that the e-unit should switch at 7-8 volts.
7-8 volts? Didn't know that. Thanks, Bob!
And, misard, glad to see you found the problem. Your solution reminds me of something I'd do, at least in the short term. You may want to consider a permanent fix at some point now that you know what you need for parts. Good luck with the loco!
I am using 2 throttles on a zw, and common neutral to the running rails, with one of the interior rings powering switch motors. I may want to migrate to dc power, so do I use 3 rectifiers? And I believe I have to disconnect the whistle relays? Is any of that correct?
If you're comfortable with opening up the ZW and servicing it you may be well served by replacing the antiquated rectifier disks with stud rectifiers like a 1N1183R. They fit into the opening the old discs used and give you a clean durable DC that improves the operation of the whistle. You can find parts and instructions on-line and on YouTube.
Even though the input terminals (~ and ~) of bridge rectifiers that you might connect to the output terminals of your ZW share a common connection (through the ZW's U terminals), there will be no common among the rectifiers' output terminals (+ and -). You will at least have to gap the outside rails at the block boundaries and strictly enforce no running over those boundaries when the blocks are powered from different rectifiers. Even in that case, you still will not be able to operate the switch motors from the same transformer's rectified accessory voltage unless you disable any non-derailing feature.
The simplest way to get what you want is to use a separate transformer and rectifier for each load, whether a track block or turnouts and accessories.
(BTW, a neutral is a kind of common, but the kind of common we're dealing with here is not a neutral.)
Bob, I just installed diodes in my new old ZW which now puts out about 12 volts DC in position 1 and no DC voltage in position 2. I've read that this can happen and suggestions seem to be to reduce the nichrome resistor value to up the position 2 voltage or to increase the resistor value to up the DC voltage in position 2. Do you have a recommendation on this and if so do you suggest a value and a wattage rating?
The voltage leakage between ABC and D goes away if any load is present such as a light bulb train etc.It has no amperage so it isn't usually an issue.
Kent Schwarz
Transformer sales and repairs
www.tranz4mr.com
tranz4mr@tranz4mr.com
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