Quote:
Originally Posted by Skywave
Perhaps I've missed something: thoughts from other members may be helpful on that point. What type of instrument did you use for those resistance measurements? DVMs, when used to measure resistance of inductors, (especially if any capacitors are involved) can give misleading results; analogue meters are preferable for that reason.
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No Al, you certainly didn't miss anything; it was purely "operator error."
I rechecked the resistances with both a 20000 ohm/volt Simpson 260 and an HP 410B VTVM and A to D read 8.4 ohms, C to E read 9.2 ohms and C to D was infinity.
I have examined the primary and secondary with a loupe and can find no evidence of another lead for that missing pin "B" feed. I am getting a strong feeling that there is a missing connection to the "B" pin. I also have observed that there is supposed to be a 1 K ohm resistor in the B+ feed to the coil which ends up providing 250 VDC on the plates of V17 and V3. There is also supposed to be a 1 K ohm resistor going to the B+ feed for transformer T4 which feeds the plate of V4. But (as you can see on my hand-drawn diagram of the underside of T3) there exists only a single 1 K ohm resistor that goes from pin "A" of T3 over to T4. I may be terribly mistaken but it seems like there should be two 1 K ohm resistors, one for T3 and the other that exists for T4. Perhaps I am missing one of them. Maybe once upon a time there was one going from pin "B" over to pinpin "D" which would supply the B+ voltage to the plates of V17 and V3. But I am fearful to rush in there and cobble together such an addition because I still wonder from where the 140 VDC on the plates is originating.