Hi to all,
Hi Bob, long time no see.
Airline AM/FM chassis, first things first:
- filaments light?
Wiring loom between PWR supply & radio chassis, do you have the various voltages present (B+), Ground solid & OK?
There are many wafer switches, all susceptible to oxydation/bad contacts.
Have you used contact cleaner (or DeoXit) & vigorously switched back & forth many times to exercise contacts.
Oscillator test: AM band, AM transistor radio next to the Airline. can you hear an oscillator "swish" on the transistor radio when you tune the Airline 455Kc (value of the IF) below the transistor radio's frequency?
Same test, FM, difference between the 2 radios should be 10.7 MHz (FM IF).
Do you have wiring continuity (GND & Signal) from the AM detector out, FM detector out to the Audio Amp input on another of the 3 chassis?
Mica Cap disease: usual symptoms are radio works or weak reception then suddenly you hear very loud "lightning crashes" in the audio. It's totally random.
Of course in severe cases if all 3 IF's have the disease, nothing works.
Course of action: this is mainly a TV forum, here we've got AM/FM radio problems.
I would post a request on ARF in this section. Also include a photo of the AM/FM schematic.
https://antiqueradios.com/forums/vie...2cb3517a24069e
Reading about silver Mica disease, an example, there's tons of info on ARF.
IF it is SMD, Guys will advise about replacement Mica cap values for AM and FM.
https://antiqueradios.com/forums/vie...t=Mica+disease
AM IF can with SMD disease, repair by photos:
https://antiqueradios.com/forums/vie...90994&start=21
Best Regards
jhalphen
Paris/France
PS : Please send me a PM, i don't have your current Mail address.