Hello and question about a westinghouse h-157

My first post here, just found this forum. If someone could look at a schematic for Westinghouse H-157 and tell me if the if's could could have the dreaded silver-mica migration? This radio was my dad's and it came from down south where humidity is very common. Among other things after being on for 10-15 min it starts static noise up like a nice electrical storm not enough to cover up a medium signal but certainly cover up a weak one. I've replaced the filters and all paper/wax caps and checked all resistors except the one in the if can..thanks in advance..Alan

Sounds like silver mica disease in i f transformers to me.
Bill Cahill

Bill Cahill wrote:Sounds like silver mica disease in i f transformers to me.
Bill Cahill

Thanks, but thats not the answer I was hoping for...looks like a darn hard job to me..Alan

You could try this...
When the radio starts making noise, try tapping, and, wiggling tubes. If one is noisy, that may be the prolbem.
Bill Cahill

I've got some problems with tuning cap that I haven't nailed down yet. I spray it and it plays fine but after it dries out I get a modulated hum. I can push and so forth on the cap and it will come and go..something there somewhere with the cap. Maybe with luck thats my static problem too...thanks, Alan

Check for cap to chassis grounding could be faulty, some caps have a bronze spring from cap frame to tuning shaft, maybe needs cleaning. And the obvious cap plates, not spaced right so they short. With an Ohmmeter, with the radio disconnected check rotor and stator plates for shorting during rotation.

Good news, can't be smd as the only cap in my if are the trimmer types and the cans are the larger type. I was told smd is is usually found in the 3/4 inch type can..On a long shift again today at work so no radio playing..thanks, Alan

Bill Cahill wrote:You could try this...
When the radio starts making noise, try tapping, and, wiggling tubes. If one is noisy, that may be the prolbem.
Bill Cahill

No silver mica disease..it doesn't have caps in the cans...When I short out the 6sa7 everything is quiet. Which means to me it is either that circuit or the tuning cap area. I was checking voltages today and when the hum was present I had a -8 volts or so between the chassis and tuning cap. When it sounded clear that dropped off to 0 V...I found a resistor in the osc circuit (r- thats resistance was 4x normal while warmed. When it cooled down it went back to 22K. I'll pick one up at the local Rad Shak and try that..I also subbed out the 6sa7 same noise..Thats the only spare tube I have for it..Alan

another thing to check is the vol. pot sometimes after ther warm up you hear a few pops and snorts out of one.other than that as bill says poke and tap around on tubes ,move wires a little and you may find a bad solder connection.try watching it in a dark room and see if you spot any arcs especially if it has those wafer looking tube sockets .they get a burn't spot and start arcing to ground have patience and you will find it.butch

Fixed and playing well. after cleaning the tuning cap and blowing it out with a air hose..thanks all..now to do something about the cabinet...Alan