Lionel SW Transformer

[Anonymous]

I have this “SW” model transformer that’s got to be close to 40 years old if not older and I think it might be going, is there any way to test it to see if it is or not? When I’m running my trains on it, the “B” train works fine, but my “A” train seems to lag at different times. I switched “A” and “B” and got the same thing. I thought it might be the track (“O” gauge bought in 58) so I tried it on a friends setup and still got the same effect. Does anyone repair these?

[ben10ben]

What sort of trains are you running on your loops?

Keep in mind that any power device will have an internal voltage drop depending on the load exerted on it. Generally speaking, a two motored engine will draw more power than a one motored engine, and can motors draw less power than older style Lionel open frame pullmor motors. The amount of power drawn also depends on the force required to move the tran it's pulling at a given speed, as well as any additional light bulbs and other devices drawing power off the transformer.

To lessen this voltage drop, it's advisable to use fairly large wire. 14 or 16 gauge is usally preferable, although larger sized wires most certainly can be used. You also need to make sure your engine is well lubricated, along with your rolling stock wheels.

What you've described doesn't really sound like a troublesome transformer.

[Anonymous]

I have 14 gauge on there right now, my Grandfather for years swore by old telephone wire, maybe he was onto something because he never had a problem. [:)]

I wish I could remember the name of everything right now. One train is a 30’s something Marx Mercury with 7 tin cars attached on a small oval loop (6 straight and 8 curves on old O gauge). The other is a 1958 Lionel 2-4-2 with 5 cars attached (4 plastic/metal, 1 all metal flatbed). This one is running on a larger loop of about 10 curves and about 11 straight on old O gauge. The larger loop is “A” and the smaller is “B” and the transformer is an old Type “SW” duel controller transformer by Lionel with the whistle button. Both trains have been serviced (one 1 month ago and the other 8 months ago) and both trains and all rolling stock got lubed again before I started running them.
I have switched “A” and “B” so that the small track was “A” and put the Lionel on there and got the same result, I put the Mercury on there, same result. I switched everything back (“A” to larger loop) and put the Marx Mercury on it and got the same result.
I even dropped the cars and ran with just the engines and it didn’t matter, same result. But the “B” side of the transformer doesn’t show problems like this. Could it be that the transformer itself isn’t bad but maybe something inside is just worn out?

[ben10ben]

Okay, I understand now. I thought you said that when you reversed them, you got the same results with the B handle that you got with the A handle.

You may have a problem with your transformer, then. It could be that the wiper arm that slides across the coils is dirty or corroded, or there might be a cold solder joint in there somewhere. If you're not comforatable dealing with it yourself, your best bet is to take it to a dealer that services old transformers.

[Anonymous]

I think this is something I could do, any "dangers" I should look for when opening it up?

[lionelsoni]

Terminal U is the common, which should be connected to the outside rails of both your loops. Terminal A is a variable voltage that is connected through the whistle control and should be connected to the center rail of whichever track might have a train with a whistle, if any. Terminal B is a fixed 19-volt accessory voltage, relative to terminal U. Terminal C is a fixed 14-volt accessory voltage, relative to terminal U. Terminal D is the other variable voltage, which should be connected to the center rail of the other loop.

[wrmcclellan]

tme1972,

This is a pretty simple transformer. There are 2 wipers on top that contact the same windings on the transformer secondary. So if one thottle is working, then the problem is with the other throttle/wiper assembly.

You did not say if it is erratic when you set and leave it at one voltage or if it is erratic when adjusting voltage.

To take it apart - first carefully pull the two handles off.

Then remove the 4 large screws on top and lift the case off.

Now you can see under the top plate where the two wipers are. You can also easily see the top of the secondary windings. Check the bronze wipers for stiffness (they are pretty stiff and have a dimple on the end that contacts the secondary coil). Check the windings where the wipers rub and look for burned wires (if the wires are fried, not much you can do about this). Clean the coil with a soft cloth first. Some alchohol could be used if necessary - don't soak it.

What I am not sure of is how to remove the wiper assembly. The manuals seem to imply that the lower washer can be removed, but on mine it is riveted (using the extension of the wiper shaft). It may be possible to unsolder the wire that goes through the top plate (via a plastic tube) and maybe the wiper assembly will slide out of the hole it is in.

The other thing to check is this wire that goes to the wiper assembly (underneath the top plate) to see if it is loose or as Ben says - a cold solder joint. You can get to this without removing the wiper assembly.

BTW - when you say A and B, do you mean right and left respectively?

Regards,
Roy

[lionelsoni]

Before you take it apart, is it wired to the track correctly?

[Anonymous]

Because I couldn’t remember the name of this set earlier, its number 1590, 4 car freight set with “Pennsy’s” 2-4-2 red striped loco.
I just went and double checked the wiring against the manual because now I’m second guessing myself here. According to the instructions and “lionelsoni” it is wired correctly with the “U” post going to the outside rail of both loops.
What I was calling “A” is the right side of the transformer or “AU” as it states on the top of the unit and “B” is the left side or “DU” as is stated on the top of the unit.
I really appreciate everyone’s help here with this, especially you “wrmcclellan” for taking the time to give me directions on how to pop this open and what to do once I get there. [;)]
I guess that the problem isn’t so much as its erratic; first and foremost it’s a power drop off at the part of the loop farthest away from the transformer (on smaller loop as well as larger loop). I connected an old Marx lamp post via a lock on and with the voltage set and no train running the light flickered like mad. I have 2 other lights and they both did the same thing. I’m about to get a voltage meter and check what the “high” voltage is at “full throttle”. But again, this is only affecting the right side (AU posts).
Still think it might just need some attention inside the case or am I looking at something bigger?
If this transformer is going, what do you all recommend that I go to considering the age of these 2 trains?

[lionelsoni]

Open the transformer. If one side works, there is hope for the other. The A side has the whistle circuit in series, so that may be where the problem is, perhaps in the whistle-control switch. If that's it and you can't fix it for some reason, you can just remove the whistle circuit and wire around it, since I think from your other postings that you don't have any whistles anyway. Here is the service information:
http://pictures.olsenstoy.com/searchcd31.htm?itm=665

[Anonymous]

lionelsoni it’s funny that you mention about the whistle switch. Since this was my Grandfathers set and me being a little kid at the time, I was under strict orders to never pu***hat button. Well we all know how kids are so I pushed it and pushed it, he’s been gone for 20 years now and when he passed I started to listen and baby these things. But I remember that whenever I did pu***he button everything would get brighter and the train would really start to roll, almost like it got a burst of more power. Should that happen? Or could this be related to the problems I am having now? Oh and thanks for the link to the service manual, I’m going to open it up Saturday morning, I sure hope your all here then in case I goof!![:)]

[lionelsoni]

The increase in voltage is normal and deliberate. It was meant to compensate for the loss in voltage from introducing the rectifier that produces the few volts of DC that operate the whistle relay and for the additional load of the whistle motor. The amount needed depends on the locomotive, the load of the train, the track voltage, and so on; and Lionel tended to overcompensate, leading to the familiar speedup.

[stuartmit]

 The lower variable range here, 0-14 v runs my 773 better than the AU conbinaction on the RW. The greater wattage capacity is with the SW.  even at lower voltage the 773 performs better