I have an old SX-780 that I keep down in my studio. It's rated at 150 watts. Occasionally at high volumes the sound goes out completely. This happens about every other year or so. I always take it to a local repair center and they fix it for about $65 a pop. I have never asked what they replace, but the last time it was repaired the receiver only lasted about 2 months until the volume went out again.
Does anyone know what is happening, and can I have someone do a mod so this doesn't happen again?
I would hate to shelf this thing for good. I had it for so many years and when it works properly it sounds great.
Thanks!
Paging Soundmaster G Pioneer SX-780 Question
Moderator: jingle_jangle
Paging Soundmaster G Pioneer SX-780 Question
Buy it before someone else does.
-
soundmasterg
- RRF Consultant
- Posts: 1923
- Joined: Tue Oct 01, 2002 1:06 pm
I have no idea what that Pioneer is. Is it tube? Transistor? If it is tube, it could have an oscillation that causes it to shut down audibly, but it is still working very hard at amplifying high frequencies. This is usually due to a poor layout inside the amp and can be fixed by moving components or wire around. It is very hard to troubleshoot and fix something like this.
If it is transistor, it sounds like it could be going into thermal runaway, and when it does this the power transistors blow, making the unit non-functional. If this is the case, then the amp needs to run cooler. You can heatsink the power transistors to the chassis. You can open the case and run it with a fan right on it, etc. It would help to know what the failure mode of the unit is as I'm just guessing off the top of my head here. I have very little experience with transistor things and only know a couple basic things about them that I've read about. I'd ask the repair place what the failure mode has been and what it is they are fixing whenever it goes bad.
If it is transistor, it sounds like it could be going into thermal runaway, and when it does this the power transistors blow, making the unit non-functional. If this is the case, then the amp needs to run cooler. You can heatsink the power transistors to the chassis. You can open the case and run it with a fan right on it, etc. It would help to know what the failure mode of the unit is as I'm just guessing off the top of my head here. I have very little experience with transistor things and only know a couple basic things about them that I've read about. I'd ask the repair place what the failure mode has been and what it is they are fixing whenever it goes bad.