I've acquired a Lionel ZW transformer and checking the voltage, I find
that the 4 terminals all have a high voltage of 21.4. What surprises me
is that in the off positon, A and D run about 3 volts and B and C about
1.5. I would think that the 4 terminals should read 0 volts in the off
postion. Otherwise, could not the windings of locomotive motors burn
I would appreciate knowing whether my ZW is defective or typical.
Your ZW has problems. In the "Off" position, the moving contacts should be
resting on an insulating pad and not contacting the transformer secondary
winding. The B and C circuits are a direct path from the moving contacts to
the respective terminals. If you see any voltage, it means the contacts are
probably not moving off the windings. This could be due to broken or worn
carbon contact rollers, so the metal frame is rubbing on and possibly
cutting the copper windings, or it could be due to slop where the moving
contact arms are attached to the control shafts so the contact arms are not
moving all the way to the off position. These same problems could be
causing the voltage that you are seeing on the A and D terminals, but in
addition, these circuits have the whistle controls, which include a 5 volt
compensating winding to provide additional voltage to the train when the
whistle is activated. The whistle control contacts may be bent or not
returning to the normal position, providing voltage from the compensating
winding to the A and D terminals. Unplug the transformer and open the case
visually inspect these areas.
You may want to look at the origianl Lionel Service Manual sheets for the ZW
which are on line at:
Good luck, Geezer
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