Sony GX99ES seems to be overheating (1 Viewer)

[RickMurray]

I'm new to this forum and surely hope someone who knows this amp can give me an idea what the problem really is. I don't like the thought of having a local repair shop throw parts at it blindly.

I purchased one of these receivers last March, on eBay. It's a great machine, and little by little I'm learning how to use it. Problem is (and I've gotten no response from the guy I bought it from) it shuts off some part of its circuitry after playing for a while - sometimes 5 minutes, sometimes 2 hours or more. It acts as though something is overheating. After being shut off for a while (I've never tested how soon it can restart) it works fine again. When it does fail, it goes through awful noises like something is shorting or slowly opening (noises through the speakers, not audible directly from the amp). Then it's quiet. On any normal startup, it's quiet briefly until it sounds like a relay closes or something and then it starts and works just fine.

Is there a common problem with these things overheating? I have it on a shelf with 3/4" spacers under the feet to make sure it gets plenty of air from below and there is nothing on top of it. I'm running 4 old Sansui speakers, 8 ohms, all. My listening room isn't very large so I seldom have the volume over 4 1/2 on a 10 scale. I have a subwoofer
connected to the high impedance jack. When it's on, everything sounds great, all the controls work as expected, no sign of problems.

Can you suggest who I should be talking to about this thing? Or what can be done to keep it going? I've tried a small cooling fan on top of it, located where it would pull air through the tuner section, but so far, no change. The big power transisters in the amp section are all on a giant heat sink. I don't see any sign if high temps on any of them.

On part of the circuit board in the tuner section, the varnish coating is browned somewhat suggesting heat there. I haven't identified which components might be overheating there, though. I can send photos of most of these locations.

It's been suggested that if I'm playing it in a surround sound mode where it tries to drive a center speaker (there is none) it may overheat something. However, when I avoid that mode and even limit it to simple stereo, it still chokes.

I'd appreciate some comment or suggestion.

 

[Ed Moxley]

A lot of times, overheating is caused by frayed speaker wires.
Check both ends of each speaker wire, and make sure it's a clean twist and contact. Single strands can touch something they shouldn't, and cause overheating. Re-twist the wire and insert.
Good luck!

 

[RickMurray]

Thanks for the reply. I have all new speaker wires with twisted and soldered ends. The owners manual states, under trouble shooting, that shutdowns may be caused by external shorts - as you suggest - in which case a "protector" message will flash on the display. I've seen this message a few times, but very rarely compared to the number of shutdowns. Not at all recently. I have checked all my external connections and find nothing suspicious. I suppose that there may be a problem in one of my speakers. I haven't disassembled them to see.

 

[Ed Moxley]

I don't know what else to tell you. I was gonna say..........if you use 4 ohm speakers, with an 8 ohm receiver, and play at loud volumes, that can cause overheating too. But, you said all your speakers are 8 ohm.
I know you don't want to hear this, but the receiver could be going bad. Maybe someone else, with other suggestions, will chime in.
Good luck!