From: calinski@calspan.com (Peter Calinski)
Subject: Help with a Lionel Transformer
Organization: Calspan Advanced Technology Center
Distribution: usa
Date: Sun, 13 Dec 1992 01:38:34 GMT

I have an old (1950's) Lionel transformer model "TW".  It seems to have 
developed two problems.

1 The current limit doesn't seem to work.  If you short something (eg a wheel
  goes off the track), it delivers full current and over heats.

2 The speed control won't reduce the voltage to zero.  It only goes down to
  5.5 Vac or so. The transformer wiper goes all the way to the end so it isn't
  a mechanical problem. There seems to be another wire off from the wiper that
  is delivering the 5.5 Vac.

If someone has the whole answer, that would be great but in the meantime, if
anyone can answer some of the following questions, I can start thinking about
a solution. (A full description of the Transformer follows the questions.)

a) How do they do current limiting?  There appears to be circuit breaker type
   devices that are temp. activated but they don't seem to work.  They stay
   engaged even under a direct short.  There are 2 of them but neither seems
   to be in the speed control circuit. (I can't trace the circuit without
   drilling out some rivits. I would like to avoid that if possible.)

b) There is an odd device. It consists of a copper colored disk held against
   a bracket.  The bracket has a wire on it and the center of the disk is 
   connected to the whistle switch.  What is it/What does it do?

c) What is the principle used for the whistle?  The whistle switch seems to 
   increase the output voltage by 7 or 8 Vac. 

d) Is there anywhere I can get info on this transformer?

Thanks in advance.

DESCRIPTION OF TRANSFORMER FOLLOWS

It is labeled TYPE TW,  175 watts

It has 2 controls. One labeled "OFF 7 10 13 15 18".  The other DIRECTION to 
the left and WHISTLE to the right.

It has a light that used to go dim if there was a short on the track.  In this
mode, there was still a small current delivered to the load. As soon as the 
short was removed the light went to full brightness and full power was 
restored.

The terminals are labeled:


    C   U   A    A    D    E    F
    |       |    | 14V      14V |
    |__18V__|    |_____25V______|
            COMMON 

The speed voltage is between U and A.

There are 2 transformers inside.  The first has the speed control wiper on it.
It seems to have one secondary.  One side goes through the breaker to the left
A terminal, the other side is a bare winding that the wiper rubs on.  The top
(highest voltage end) goes to terminal C.

The other transformer appears to provide the A,D,E,F terminals but there could
be some connections between the two transformers. The second breaker could be 
in this circuit.


The light and DIRECTION/WHISTLE switch are tough to trace.  Three or four wires
go down under the transformers and to that disk device.

Well that's all I can think of for now.  I haven't used this train in 5 or 6
years.  My son is 9 now and is starting to show an interest. I would like to
promot it.  I got this train when I was about his age.

Thanks again

calinski@calspan.com
Newsgroups: rec.models.railroad