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Rubber covered wire on power transformers - Printable Version

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Rubber covered wire on power transformers - davemc - 10-24-2007

The power transformer on my 40-216 has rubber covered wire. It is currently intact (other rubber wire in the radio is falling apart). I'm sure, if disturbed, so would this wire! I also worry about the points where the wiring passes through the transformer shell. No shorts now, but ....?

I hesitate to attempt to repair it for fear of damaging the transformer. In other radios I have pulled the transformer and replaced the wiring by splicing onto the extant wires near the anchor point. I suppose I could also just apply spaghetti tubing and/or shrink tubing over the existing wires (might be a safer strategy).

What's the best strategy?

For the rest of the radio, I am only replacing rubber wiring that is damaged or is disturbed by other repairs (I try to keep the radio as original as possible).

Thanks!

- 49Stude63 - 10-24-2007

Dave on one of my Philcos I took the transformer apart and soldered in new wires, model 95/96 type unit, but if I had to do it again I would just use shrink tubing and slide it up as far as I could and shrink it.

- Ron Ramirez - 10-25-2007

You could remove the transformer, remove the "bell" (cover) where the wires come through, and sleeve every wire with heat shrink tubing. Just be careful. I tried to "repair" a 1939 Philco transformer like this once; within six months, it failed (internal short).

Rubber covered wire on power transformers - Guest - 10-25-2007

I just rebuilt all three on my 41-280 using new cloth covered wiring and they all ohmed out to the values on the schematic. I'm looking forward to powering it up to see if all went correctly. If so, it should last a long while.
Rick

- Texasrocker - 10-25-2007

If you can carefully remove the AC Trans from chassis,(orig wiring connections marked for re-install), and get 1-side (under chassis side) of the cover off you should be able to "straighten" all the wires to insure you get new heat-shrink tubing cut-to-fit all the way back to their independant orig exits from all the orig windings coming out of their respective windings. I have saved many transformers using this method that had old deteriorated "orig crumbling rubber-wiring insulation" for many yrs. Just make sure you keep up with your "point-to-point" primary ,filaments, and HV connections. If you have a variac & ampmeter on your bench, you can carefully bring up the Trans leads repair and check all independant filament & HV rectifier plate voltages on your test bench before re-installing the trans to chassis. As you know, it is also important to make sure none of your "sleeving" fails by shorting out to AC Trans metal cover after adding or saving your leads by adding new heat-shrink tubing and/or new wiring. Me no scare of re-sleeving vintage AC transformer leads, but it is a tedious-job at best and be very careful checking the HV Plate & centertap leads!! Make sure their are no-shorts whatsoever before you re-assemble the trans metal housing assembly. Good luck with your restoration!! Randal