zenith: Ch= 5K02; K510

Hello,

I'm working on a zenith k510. After lots of time working in this set I can only get a volume controlable hum  out of it. The electrolitics have been replaced and all film caps. Plate voltages look to be in tolerance. To me it seams to be in the detctor stage but cant be sure. Anyone have any sugestions?

kind regards,

Bill

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I found the problem with my K510 zenith radio. It was the 2nd IF transformer. the transformer had an extra winding in it so i was able to just move 2 leads from the bad winding to the good one and the radio works great. Does anyone have more information on this type of IF can?

Kind regards,

 Bill

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The 12AT6 is a dual diode triode. Often the audio detector is drawn on left and called d' and the delayed AVC/AGC detector drawn on right and called d", however in this case the AGC is taken from audio line  and the two diodes are just wired in parallel.

When a separate AGC diode d" is used it can be fed from IF amp anode, or the d' via a small capacitor, from a separate IFT winding or tap on a shared secondary winding or a tap on the primary winding.

The schematic doesn't show the fact of a 3rd coil, but it's probably the same part as used in a more deluxe set with separate AGC detector. I've never seen a set with what in UK we would call H series valves (150mA tubes) as UK series heater chain use U series (100mA tubes). (click on the tube names to see the UK/European H equivalents).

However someone expert on Zenith or USA Radios may have a better answer.

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