Any Radio Repair Experts out there? Proton question.

[mattl]

I have a couple of Proton 320 radios from the '80s in my bathrooms, sound fine still, clocks work well to, but...

 

One of them has a very finicky tuner, have to wiggle the tuning knob, station will come in clear for a moment then drift off again with distorted audio.  Any idea how the tuners in these work, anything I can repair?

 

Doing a bit of online research I guess these are well regarded as is the Nakamicki stereo pair I use in my bedroom, going on 30 years for both.  Think I paid $120 for the Proton, over $200 for the Nakamichi pair back in the 80s, guess I got my money's worth, but hope to get more use out of the Proton.  I don't know what is available today with the sound quality that the Proton has.  Some recent vintage Boston Acoustics have favorable reviews, but NLA.  

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[kb0nes]

I remember these radios, they were a decent table top radio.

From the description of your problem there is a fairly good possibility that there is a bad solder joint on a board. This was especially common in the areas were a larger component attaches to the PC board. They likely used paper phenolic PC board material and that stuff was none too stable. I'd inspect it closely and perhaps resolder the larger connections and go from there.

Here is a link to the service manual for what it is worth.

http://www.proton.com.tw/images/201004010928127627.pdf

 

[cfz2882]

i think the same

sounds like a bad solder joint to me too-used to fixing bad solder joint on my 1980s GM Delco car radios...

 

[mattl]

Wow - thanks!  The scope of knowledge on this site is phenomenal.  I really appreciate the schematic, will tear into it soon.