Channel cutout on solid state amps

[cow dog]

Problem: channel cutout on two of my solid state amps
Equipment: Carver M-500 T amp & TX-11a preamp
Topping T22 dac/amp

Hey there y'all, it's been awhile but I thought I'd check in to see if any of you have had this problem that's been dogging me for awhile. Pardon me if it's been dealt with in other threads, but it first cropped up in my Carver stack some time ago, and even after a cleaning/restoration by a local "expert" (not so sure about him now).

Here's what I'm getting: upon a cold start, the right channel volume will be very low. I'll try to balance sound by turning the balance knob about halfway - this normally does the job. Other times, the right channel seems to be out completely. I've discovered that if I briefly pot up on the volume (both channels) very high and then back off, it will "kick in" the right channel and I'll get normal balanced stereo again.

On my Topping T-22 (driving Klipsch bookshelf speakers), I've noticed a similar thing - low or missing left channel. Since that one doesn't have a balance knob, I'll just pot up volume very high for a second, and that channel will kick in for me and it'll be all right.

Any ideas? Is this a repair or maintenance scenario? Thanks for your replies and I pre-apologize if this problem has been dealt with elsewhere on this site.

 

[petehall347]

speaker relays or switches

 

[avionic]

Welcome aboard cow dog...

Protect relays if applicable as Pete has already suggested.

 

[rwartner]

You need to debug where the problem is. I thought it was capacitor in speaker. Switched wire and it moved to other speaker so in the amp. Exercised and cleaned switches nope. Swapped speaker wires from A to B bingo.
The A speaker input is touchy and the cause of my random cutout. I'd try all that.

 

[gadget73]

Speaker switch or protection relay would both give the same kind of symptoms. Cranking it likely burns through the shaky connection and welds the contacts together enough to make it work until the next time. You can polish up the relay contacts to see if that sorts it, but honestly once they get beat enough to have flaky contacts, you're better off replacing it. Often you can get the problem to repeat by gently tapping on the top of the relay. If the signal comes and goes, thats your issue. Same thing if its a speaker switch.

 

[SoCal Sam]

When all avenues are exhausted, I can recommend an excellent tech local to us.

 

[cow dog]

Thanks guys - Yeah I guess I'll try and isolate the problem by checking the speaker wires, but something tells me it's in the amps themselves. I'm not really the guy to fix things under the hood. Maybe it's time to send that carver stuff in for a real overhaul, and maybe even upgrade my desktop setup. But meanwhile, any recommendation for a reasonably priced expert in socal would be appreciated. Sam, who do you think?