I have a TA-5650 VFET amp. It has worked great for years, but every once in a while it would drop the left channel. A few times now I have blown the case out with air and the problem has gone away for a year. But it keeps coming back, and now it's lasting longer than before.
It's still intermittent. Some days it works, some days it doesn't. Sometimes it works for a while and then cuts out. Presently it is not working. When I turn on my amp, there are some scratching sounds on the left channel. If I start playing a song, it only comes out on the right channel. If I turn the balance all the way to the left, I can hear some sound but it is faint (and inaudible when the balance is even). When the music is playing, if I turn off the amp and then back on, both channels work for 2-3 seconds. If I switch the balance to the left channel and turn the volume up quite high, the speaker starts making popping and scratching noises.
The problem is not the speakers, because the behavior is the same if I swap the speakers (the problem follows the channel). I also have the same problem if I move the speakers to from the A input row to the B input row. The same behavior is also on the headphone output.
Does anyone have recommendations on how to further troubleshoot/address this problem? I'm thinking about following some instructions about cleaning controls but I don't really understand these things--I'm more of a software guy.