I am trying to restore a Silvertone model 132.881. This is an AA5 of about 1950 vintage. When I first got the set it wasn't working and the chassis was in awful shape. A few resistors had been replaced with the wrong values, the IF coil was open, and various other problems.
I have repaired the IF coil, replaced all of the tubes "twice", replaced "all" of the resistors, and replaced all of the caps except for one mica filtering cap in the detector stage. Now for the problem! The radio fires up and is fairly selective, but it has a small bit of static across the dial. After it plays for about five or six minutes the static increases and finally there's no signal anymore, only static. If I turn the set off for about five minutes and then turn it back on it will play again just as before, but this time, it plays for a shorter period of time. If I leave it off for a half hour or more, then it will play again for about five or six minutes again before fading to static. I figure the problem is heat sensitive, but I have no idea as to where to start. I'm new to radio restoration, so I'm open for any help anyone can give.

:I am trying to restore a Silvertone model 132.881. This is an AA5 of about 1950 vintage. When I first got the set it wasn't working and the chassis was in awful shape. A few resistors had been replaced with the wrong values, the IF coil was open, and various other problems.
:I have repaired the IF coil, replaced all of the tubes "twice", replaced "all" of the resistors, and replaced all of the caps except for one mica filtering cap in the detector stage. Now for the problem! The radio fires up and is fairly selective, but it has a small bit of static across the dial. After it plays for about five or six minutes the static increases and finally there's no signal anymore, only static. If I turn the set off for about five minutes and then turn it back on it will play again just as before, but this time, it plays for a shorter period of time. If I leave it off for a half hour or more, then it will play again for about five or six minutes again before fading to static. I figure the problem is heat sensitive, but I have no idea as to where to start. I'm new to radio restoration, so I'm open for any help anyone can give.
:Hi I have one of these radios myself, had the very same problem, came to find out I had bad connections on the "12BE6" tube pins and socket, I carefully cleaned the pins of the tube and put it back in, and it worked perfectly, if this doesn't fix it then try cleaning the pins of the tube and replacing the socket, that should do it.
Mark

Hi Leon

If this radio uses small IF Transformer, less than 1" square, with one adjustment on top & bottom, they have built in silver mica caps. These caps can short over time and give static. It usually gets worse as a radio heats until only static is heard.

Caps can be dug out of the base of an IF Transformer. New external caps around 100pf should be added.

Norm

:I am trying to restore a Silvertone model 132.881. This is an AA5 of about 1950 vintage. When I first got the set it wasn't working and the chassis was in awful shape. A few resistors had been replaced with the wrong values, the IF coil was open, and various other problems.
:I have repaired the IF coil, replaced all of the tubes "twice", replaced "all" of the resistors, and replaced all of the caps except for one mica filtering cap in the detector stage. Now for the problem! The radio fires up and is fairly selective, but it has a small bit of static across the dial. After it plays for about five or six minutes the static increases and finally there's no signal anymore, only static. If I turn the set off for about five minutes and then turn it back on it will play again just as before, but this time, it plays for a shorter period of time. If I leave it off for a half hour or more, then it will play again for about five or six minutes again before fading to static. I figure the problem is heat sensitive, but I have no idea as to where to start. I'm new to radio restoration, so I'm open for any help anyone can give.

AND! that mica filtering cap you didn't replace in the detector stage.... I have a Telechron radio that likes to sputter and crackle after a while, and the audio goes away. Turned out to be a mica filtering cap in the detector/audio stage...actually was a mica cap. on the plate of the 1st audio amplifier, which is subject to B+, but either way...if it isn't subject to B+ it can still cause this trouble. The way you describe your trouble, though, Norm's idea sounds more realistic. The mica filtering cap. is easier to replace, so try replacing it, but go for the IF condensers, too. Sometimes you can catch a shorting condenser in the IF section by measuring voltage. If it's on the grid side, this is difficult, but if it's on the plate side, which is the side that usually fails, you can measure the voltage at the plate, which will jump around a bit if the condenser is arcing inside.

Never overlook mica condensers. Another little wonder you'll find is that sometimes they aren't even mica. All of the supposedly mica condensers in my 630TS television were leaky and caused tons of trouble (sputterning, picture jumping, you name it). Cracked them open and they were PAPER CONDENSERS! The bakelite condensers with the colored dots are on occasion paper. There is a color code for this that is occasionally marked on the condenser. I forgot what it is. More likely, though, you have mica condensers, which do fail on rare occasion.

T.D.

Thomas:
I finally got this radio working. It was, as Norm said, a bad cap in the IF. After repairing the bad cap, the radio plays fine. In fact, I'm listening to it as I type this reply.
Leon