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St. Paul MN 55112 |
After some use the interstage transformer failed in my radio. I purchased a P-T156 replacement winding from Antique Electronic Supply and installed it in the transformer as shown here with the original failed coil on the left and the new coil on the right. The transformer uses scrapless E-I laminations but they are not interleaved so it is easy to lift the I lamination section, slip out the old coil and slip the new coil in its place, then reassemble the transformer. My initial attempt ended up with a shorted secondary due to
contact between the secondary terminal screws and the shell of
the transformer. The windings are soldered to terminals mounted in a rubber like insulating material that has shoulders that press through the shell of the transformer to insulate the terminals from the shell. With the original coil the body of the coil forces the insulation to remain in place but with the new coil which is much shorter, the insulators would push back into the shell allowing the external screw end of the terminal to contact the shell. After a failed attempt to glue the insulator material to the shell, I finally drilled a hole in each shell between the terminals and drove a wood screw through the hole and into the insulator material between the terminal. These screws held the terminals in place and allowed the transformer to be reinstalled in the radio and to work correctly. For just a couple dollars more, it is
possible to purchase a complete transformer and avoid this
problem, but, of course, the new transformer would look
different than the original.
This picture shows the transformer mounted in the radio/ The red arrow points to the wood screw added to hold the terminals in place. A similar screw was added to the other terminals, not visible in this picture.
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