From: @noway.com   
      
   Mark Zacharias wrote:   
   > "Jack" <@noway.com> wrote in message news:jtqirc$g96$1@dont-email.me...   
   >> Mark Zacharias wrote:   
   >>> "Jack" <@noway.com> wrote in message news:jtnp3c$dcf$1@dont-email.me...   
   >>>> Jack wrote:   
   >>>>> After a week of playing with no problems, the right channel went out.   
   >>>>> It   
   >>>>> was the left channel previously. I was dismayed until I remembered   
   >>>>> that,   
   >>>>> when I reseated the output trannies, I switch them, left for right. I   
   >>>>> was further heartened when that same trick of switching off the   
   >>>>> speakers   
   >>>>> and turning the volume up to max brought the sound back. Since there   
   >>>>> are   
   >>>>> a pair of outputs in each channel, switching one of them again and   
   >>>>> waiting to see which channel goes out next should tell me which tranny   
   >>>>> is bad.   
   >>>> After switching back one pair of the output transistors, the PNP's, NEC   
   >>>> B539A's, the problem stayed in the right channel, so I replaced the   
   >>>> right channel NPN, an NEC D287A with an NTE284. It's playing fine at the   
   >>>> moment. I will button it up and consider it fixed until it tells me it   
   >>>> isn't.   
   >>>>   
   >>>> Jack   
   >>>   
   >>> If you have not cleaned the relay contacts yet - you are wasting your   
   >>> time.   
   >>>   
   >>> Mark Z.   
   >> I cleaned the relays a couple of years ago when I tried to tackle this   
   >> the first time. Buffed the contacts with 1200 grit wet/dry sandpaper.   
   >> This time I tested the relays by bridging them when the bad channel was   
   >> out. didn't help. It wasn't the relay. The problem followed the NPN   
   >> output transistor when a swapped them left to right and right to left.   
   >   
   >   
   > OK, but 1200 grit...Wow. The coating on the contacts must not be too good   
   > anymore...   
   >   
   > I've used 6000 grit in the past and even that was too much.   
   >   
   > I'm not sure swapping the transistor really revealed the nature of the   
   > problem. As I'm sure you have seen, often we do something, it seems to fix   
   > the problem, then re-occurs later.   
   >   
   > You may very well have both channels cutting out at differnt times.   
   >   
   > I'm getting in on this late... have you cleaned the front panel push-button   
   > controls? They were NOTORIOUS for cutting out on this model.   
   >   
   > Mark Z.   
   >   
      
   Mark,   
      
   The problem returned while playing an FM station. I clicked the Phono-1   
   button and then the FM button again and the channel came right back.   
   Something new to delve into.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)