5 Years ago my Alesis RA300 monitor amp lost a channel. After troubleshooting for a week or two I got pissed and bought a new amp. I kept the old one because one channel still worked. Cut to today. My new mixer showed up and I was cleaning house and noticed the dusty old Alesis amp sitting unused in the rack and pulled it out to throw away. Turning it around I notice the bridged mono/stereo selector switch was half-way between positions. Hmmmm.....
Well, after posting this I was riding high, thinking my amp was just fine and that the problems I experienced years ago where due to user error. After almost a day of problem-free operation the "old problem" resurfaced. The channels started flickering in and out on both sides now, then it would go out altogether.
I looked online and found many RA150 and RA300 owners with the exact same problem; and and it would go away temporarily when the case was tapped hard. The REAL problem turns out to be a defective relay with weak contacts that will vibrate and make/break contact.
I desoldered the old one, found a replacement at RadioShack; soldered it in and have been problem free for 2 whole days! I've been running it constantly under different loads and while tapping the hell out of it. It remains rock-solid.
