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I am in the process of restoring a model 46-1226-125 Radio-Phonograph Console and have replaced all paper/electrolytic caps and several bad resistors. I now have audio with static noise. However, audio with the 6J5 removed is clean, but weaker of course. Before I dig deeper into the circuits, has anyone encountered this before and willing to share their sugestions? Also, any idea on the original resistor wattage for the power supply 1300 ohm resistor R103 (production code 125)? Thanks!
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City: Ferdinand
State, Province, Country: Indiana
Hi
Last question first: R103 is 10 watts, according to Philco's 1949 parts catalog. If this part is bad I would replace it with a 25 watt resistor. (Of course, if this part were bad you would lose B+ to most of the set, rendering it inoperative.)
Is the set producing any sound with the 6J5 in the socket? Is the 6J5 good? Check R209, C207, C208. Also R210 and R211.
Audio would have to pass through C206, R208, R210 and C208 to reach one of the 6K6GT output tubes with the 6J5 removed, and this audio would be at a low level due to taking those detours through resistors R208 and R210, a path the signal would not normally take since it is supposed to be phase shifted by the 6J5 tube and applied to both 6K6GT grids.
Check R212 and R213, also.
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Ron Ramirez
Ferdinand IN
Posts: 4
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Joined: Jun 2011
Thanks for the help. I'll go check those resistors again. I asked about the 1300 ohm resistor wattage simply because it gets very, very hot and was apparently replaced by a previous owner. It is 10 watt, but for the long haul, I will likely go with a 25 watt if I can find the right value.
With my audio generator connected to the test connector, I get clean audio to the speaker, weak as you state, without the 6J5 installed. Volume and tone seem to work fine. With the 6J5 re-installed, I immediately get noise, a crackling popping noise (bit like shot noise), in the speaker that is not affected by the volume and tone controls. However, the audio signal is present in addition to the noise, but overshadowed by the noise.
I tested the 6J5 and it appears to be well within the "good" range. So, I'll go dig some more into potential offending components. All the coupling and paper capacitors have been replaced but no mica capacitors.
Thanks again for the help, and any further ideas you might have.
Len
