GE 578 crackling

[superdeez]

Hi, all, I hope this is the right forum to post my question:

GE 578 clock radio. Some years ago it used to work well for a time, then it would begin to crackle and produce unintelligible audio. I replaced the tubes today (I have more free time on my hands lately) and that brought it back to life, but it is still after a time popping and giving me garbled audio. It sounds good and loud when it works, but then it again begins to make nose.

Could anyone give me a hunch where to begin troubleshooting? I have a photofact, but I'd rather not replace every component in the set if I could avoid it. Audio output transformer failure? Hard to tell from afar, I know, but I'd like to bring it back again. Clock still keeps perfect time.

[maxhifi]

Google the phrase "silver mica disease"

[JohnCT]

Originally Posted by maxhifi

Google the phrase "silver mica disease"

When I was a kid, my dad would hand me a small plastic flip open display box with two IF cans in it, and point me to an AA5 (dad hated PC work). I changed a lot of them.

"Make sure you don't mix the two up when you install them!"

"Okay dad"...


John

[jr_tech]

Garbled audio usually is caused by bad (leaky) capacitors in the audio stages.

jr

[Electronic M]

If there is any 60Hz buzz or him in the audio you should change the electrolytic capacitors too.

AA5s usually have less than $15 worth of paper and electrolytic caps in them and those caps are time bombs... Better to change them as a preventative maintenance.

[MadMan]

Wiggle all the tubes to clean the contacts. But yeah, silver mica disease.

I have a 660 clock radio, I wonder how similar they are/ aren't.