The PHILCO Phorum
GE M 65 Volume issues - Printable Version

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GE M 65 Volume issues - jph14 - 10-02-2014

Started on GE M -65( I believe this is identical to RCA 221) and cannot get any volume control. I replaced electrolytics and all other caps.
The pot that was in there I believe is not the right one. According to what I see on the schematic, I need a tapped pot. I cannot find the value of the tap, I have a 250,000 k pot that has a 125,000 k tap. don't know if this is correct. Gave it a try-- medium volume, no control. Found that a 2A7 was in the place of the 2B7, put  2B7 in and volume went down but still no control (AVC here?). Am currently checking resistors and have replaced a few out of spec ones, still working on that angle, the resistor board is next. Also found 2A5 to be very weak, ordered one. Tone control was cleaned and does work.
Any ideas? Last four pages of attachment are for this radio.

RE: GE M 65 Volume issues - Radioroslyn - 10-02-2014

I'd get a new 2A5 in there and do an alignment. You may find that you got a bad IF can or just badly out of tune.
Terry

RE: GE M 65 Volume issues - jph14 - 10-03-2014

Any idea what the correct pot should be? 
Thanks

RE: GE M 65 Volume issues - BrendaAnnD - 10-03-2014

According to this schematic, it does look like a 250K with a loudness tap. Tap isn't super critical.

As far as your volume issue, check to make sure your pot has continuity (250K across the outer terminals), and check R13, 850 ohms, to make sure it's good. I suspect it's gone a ways up in value, and since it looks like a bias resistor for the tube as well as the ground return for the volume control it could be giving you problems.

Also check R10 and R11 (both 1M ohm) as these are in your AVC circuit and almost assuredly have gone up in value. I've seen these go as much as 500% high, or open.

RE: GE M 65 Volume issues - jph14 - 10-04-2014

Thanks. These three resistors were first three checked. Both 1 Meg's were way high and the 850 was over a thousand. Had the 1 meg but not the 850- replaced with a 1 K- is that ok?
The pot is checking out Ok. Waiting on the 2A5.
Thanks again. Will get back with results. Plan on looking at if cans after checking resistor board.

RE: GE M 65 Volume issues - jph14 - 10-12-2014

No real change with new tube. Wonder if pot is incorrectly wired. How should this be wired? 
Thanks,
Joe

RE: GE M 65 Volume issues - jph14 - 10-21-2014

Have replaced all resistors- almost everyone out of spec. Replaced any cracked, brittle wire. Had a little more volume but no control. Still not sure if pot is wired correctly. Any thoughts or ideas would be appreciated. Will recheck everything done so far, even recheck the tubes.
Thanks,
Joe