The PHILCO Phorum

Tim, I'm in the middle of a 610 rebuild and maybe you can help me out. There is a 32K resistor, #42, off of the filter can #41 that riders shows going to a mica #7 and pin 4 of the 6A7, grid 2. In my chassis the resistor goes to the mica and thats it. It does not connect to the 6A7. That grid only connects to the oscillator coil. I've looked and can't find a change that shows this connection. Is that how yours is wired?

Hi Jim,
Don't have a 610 in front of me but bottom line is that grid #2 in the 6A7 must have some HV on it. This is what the 32K resistor supplies. The mica cap is to couple signal from that grid (#2 which is acting as the plate for the oscillator) over to the primary of the oscillator coil thru the bandswitch.
Without HV applied to grid 2 the oscillator section will not operate.
Hope this helps.

Hello TV Man
I restored my Philco 610b like 10 years ago it really turned out nice I restuffed the caps Also I had redo the cabinets finish

Terry, that makes sense but the pin 4 on the 6A7 in this chassis looks like there never was another connection on it other than the one to the oscillator coil. Looking at the schematic in Riders there is no direct connection to the oscillator coil from pin 4 of the 6A7. Maybe I should start another thread on this but since Tim is working on this same model I'm hoping he'll chime in on what he has found concerning this.

Jim, I've got the mica cap and the resistor going to pin 4.  I've got three 610's but only checked two of them.
Keith

and that little flex resister on that capacitor block,,,,are SOO,,sensitive ---don't touch the cloth

Hmmm, the mica in mine is connected across that 2 terminal strip with no connection to pin 4 and the resistor is connected to the point on the terminal strip closest to the 6A7.

Again, no connection to the 6A7.

Sorry guys, been away for awhile. Work started for the season so I haven't been able to spend much time at the bench lately. I just checked mine and my 32k resistor #42 does go the 6A7 and the mica you are talking about. Oh, ditto on the flex resistor. I replaced mine. It would change value as it was moved.

Maybe this will help:
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Thanks for the pictures. As you can see, in mine the mica is across that small terminal strip. On the right side of that strip I have a wire going to the front section of the selector switch and a 51K resistor to ground. What do you guys have?

I finally had a chance to escape (thank you rain!) and got back to the bench. I managed to get the tuner shaft greased and back together, installed it back on the tuner, lubed up the bearings and gave a check. Ahhh, nice an smooth . I just realized I need to get some rubber bushings to mount the tuner back on the chassis (forgot all about 'em), so back on hold til those get ordered. Tried some grommets, but they were too thin. Might as well spend the money and try to get the right parts.
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Jim, the wiring on mine matches the schematic. You got me scratching my head over yours. From your picture, things look factory wired to me. Might leave it as is and see what your results are before changing anything. That is, IF things look like it was always that way. If you have problems, THEN start checking that real close. Could be some kind of factory change. I know mine has the wire going to the band switch from the mica, then from the other side of the mica to the 6A7 grid with #42 (32k) resistor feeding the circuit.

I took your advice Tim and I now have a working 610. Turns out that the mica was connected to pin 4 of the 6A7. What I didn't know was it was connected to a tie point inside of the oscillator coil can.

Glad to hear that! I got the rubber spacers in so hopefully I can get this ready to power up.

I finally had a chance to work on this some more. Got the tuner spacers in and the tuner mounted, soldered up and ready.
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I got the tone control back in and the new power cord on. I still need to connect the speaker. She isn't far from the first power up attempt. The real fun is about to begin.
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I replaced the speaker wiring and got it reconnected. Tubes were re-tested - all test strong. Ok, now I do a very careful check of all my work.
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