07-25-2011, 09:05 AM
Well, I'm almost to the point of storing this set, advertising, & searching for another 18T chassis, and starting over from scratch as it seems this chassis will continue to refuse to cooperate with me. It amazes me that I can get higher end sets like a Philco 16, 116 with all the restoration issues they could have to play perfectly, but middle of the road sets like this RCA, and little AA5's befuddle me sometimes.
Terry, I measured the resistance while turning the bandswitch as you suggested in your last reply. At most I get 4 ohms on one of the bands, the other positions, 1 or 2 ohms so apparently the bandswitch is ok. The 33K resistor you mention was changed to 56K in my run of the set, and that's the reading I get from pin 5 to ground on the 6SA7. My 6SA7 is metal, I replaced the new 68pf mica cap with another new cap, and cleaned the trimmer cap on the tuning capacitor as Exray suggested. Nothing has helped.
What stumps me is the fact that at "first turn on" after the rebuild, I HAD A SIGNAL, a small one of a local powerhouse AM station, then it faded away to nothing. Days later I turned it on again, this time no station received at all. Except for the fact I have plenty of audio and interference from overhead fluorescent lighting, this radio just DIED, and said "NOPE..I'm retired, not playing for you..."
The only possibility of something I did wrong that I can think of is that I did use some oil on the tuning cap (ball bearings in front, other turning point friction areas) to loosen it up a bit so that there wouldn't be undue stress on the old dial cord. I just wonder if some oil didn't sneak in & drip into somewhere it shouldn't have gone. I could clean it all out again, and see what happens.
There is a bit of a mystery burning smell coming from a coil, I think, but apparently the coil isn't burning out as all resistances check out.
As mentioned in my original post, my set has the added coil for push buttons. It's potted in tar and seems to get warm. I've disconnected it for the time being, but connected or not, no change, and when connected the voltages on tubes go way down to almost nothing. Disconnected, the voltages are decent as I reported in my 1st post.
So, I'm stumped and ready to search for another chassis, I guess.
Terry, I would appreciate pics of your set if you wanted to go through the effort (e-mail to ebm421 AT frontier DOT com) . My chassis might be a later version of yours though since you mentioned the 33K grid leak res., and mine has the 56K changed resistor as mentioned in the service data.
Terry, I measured the resistance while turning the bandswitch as you suggested in your last reply. At most I get 4 ohms on one of the bands, the other positions, 1 or 2 ohms so apparently the bandswitch is ok. The 33K resistor you mention was changed to 56K in my run of the set, and that's the reading I get from pin 5 to ground on the 6SA7. My 6SA7 is metal, I replaced the new 68pf mica cap with another new cap, and cleaned the trimmer cap on the tuning capacitor as Exray suggested. Nothing has helped.
What stumps me is the fact that at "first turn on" after the rebuild, I HAD A SIGNAL, a small one of a local powerhouse AM station, then it faded away to nothing. Days later I turned it on again, this time no station received at all. Except for the fact I have plenty of audio and interference from overhead fluorescent lighting, this radio just DIED, and said "NOPE..I'm retired, not playing for you..."
The only possibility of something I did wrong that I can think of is that I did use some oil on the tuning cap (ball bearings in front, other turning point friction areas) to loosen it up a bit so that there wouldn't be undue stress on the old dial cord. I just wonder if some oil didn't sneak in & drip into somewhere it shouldn't have gone. I could clean it all out again, and see what happens.
There is a bit of a mystery burning smell coming from a coil, I think, but apparently the coil isn't burning out as all resistances check out.
As mentioned in my original post, my set has the added coil for push buttons. It's potted in tar and seems to get warm. I've disconnected it for the time being, but connected or not, no change, and when connected the voltages on tubes go way down to almost nothing. Disconnected, the voltages are decent as I reported in my 1st post.
So, I'm stumped and ready to search for another chassis, I guess.
Terry, I would appreciate pics of your set if you wanted to go through the effort (e-mail to ebm421 AT frontier DOT com) . My chassis might be a later version of yours though since you mentioned the 33K grid leak res., and mine has the 56K changed resistor as mentioned in the service data.
