Intermittent static on one channel Yamaha power amp

[Deleted member 48726]

Hi there, experts

I have a Yamaha P3200 power amp.
A minidsp is connected to it as a preamp. A Chromecast Audio is connected to the minidsp via. Toslink.
When playing at low volume, once in a while the sound in the right channel cuts out, not completely though. I can get it to play again by raising the volume on the chromecast and turning the gain knob higher. Then it starts to crackle and make static noise for a few seconds and then the sound is back. I can then turn back the gain knob and it sounds alright again.

This problem is only ocurring when the volume is low.

I have changed the speaker output relays. The problem was present before I changed them. I thought it might be the relays. Turns out it isn't as easy as that.

I checked for bad solder joints when I changed the relays and dabbed a few suspects.

-What's next?

 

[Deleted member 48726]

Oh, and the problem is isolated to the right channel only. Tried switching speakers and input. I have two identical amplifiers and the other is working fine with the same setup. I could just use the other, but I want to fix this one.

 

[rwortman]

The problem is likely with your gain knob potentiometer. Cleaning it might fix it, replacing will fix it.

 

[sarumbear]

Hi there, experts

I have a Yamaha P3200 power amp.
A minidsp is connected to it as a preamp. A Chromecast Audio is connected to the minidsp via. Toslink.
When playing at low volume, once in a while the sound in the right channel cuts out, not completely though. I can get it to play again by raising the volume on the chromecast and turning the gain knob higher. Then it starts to crackle and make static noise for a few seconds and then the sound is back. I can then turn back the gain knob and it sounds alright again.

This problem is only ocurring when the volume is low.

I have changed the speaker output relays. The problem was present before I changed them. I thought it might be the relays. Turns out it isn't as easy as that.

I checked for bad solder joints when I changed the relays and dabbed a few suspects.

-What's next?

Where/what is your volume control?

 

[Deleted member 48726]

Where/what is your volume control?

Volume is controlled by Chromecast via. minidsp to amplifier.

 

[sarumbear]

Volume is controlled by Chromecast via. minidsp to amplifier.

In other words, digitally.

Try adjusting the volume control of the right channel of the power amplifier when the audio issue occurs to be sure it’s not a pot issue.

 

[Deleted member 48726]

In other words, digitally.

Try adjusting the volume control of the right channel of the power amplifier when the audio issue occurs to be sure it’s not a pot issue.

It doesn't seem to matter where the gain is set on the amp. The issue comes when the input is sufficiently low. This triggers the issue and I can trigger it any time now with gain high or low, just by turning input signal volume to the lowest setting and wait. Sometimes it does it in five min. other days it is hours.

 

[restorer-john]

Check and clean your parallel/BTL/2ch mode switch on the rear panel. That could causing the problem you describe.

Cheers.

 

[Deleted member 48726]

Check and clean your parallel/BTL/2ch mode switch on the rear panel. That could causing the problem you describe.

Cheers.

Wouldn't have given that switch a thought! -Thank you, I will try that later when I can muster the will to carry heavy amplifier once again

 

[Deleted member 48726]

Check and clean your parallel/BTL/2ch mode switch on the rear panel. That could causing the problem you describe.

Cheers.

It was exactly that. Hooked it up to an ipad and a test speaker, as soon as i touched the switch it scratched and popped. Contact spray and canned air fixed it and it is playing in the living room again. Cleaned the other amp as well.

Thank you.

Peace.

 

[sarumbear]

It doesn't seem to matter where the gain is set on the amp. The issue comes when the input is sufficiently low. This triggers the issue and I can trigger it any time now with gain high or low, just by turning input signal volume to the lowest setting and wait. Sometimes it does it in five min. other days it is hours.

I'm happy that @restorer-john 's suggestion solved your problem. A pot could have easily caused the problem. A pot on a power amplifier does not change the gain. Amplifier has a fixed gain. The pot is an attenuator.

 

[Deleted member 48726]

I'm happy that @restorer-john 's suggestion solved your problem. A pot could have easily caused the problem. A pot on a power amplifier does not change the gain. Amplifier has a fixed gain. The pot is an attenuator.

Yeah, attenuation = reduction of value, gain the opposite. So of course attenuation it is on a power amp.

Well, the right potentiometer on my other P3200 did have a bit scratchiness inherent so it was also cleaned.

 

[TheBatsEar]

Check and clean your parallel/BTL/2ch mode switch on the rear panel. That could causing the problem you describe.

No substitute for experience.

 

[jackaudio]

@restorer-john I made an account just to say thanks for that tip! I have been at my wit's end with a yamaha p2160 - I even jumpered the old bad pots, but still had intermittent issues as described by OP. Cleaning the mono/stereo switch at the back finally fixed the issue! It's been driving me crazy for months - when the amp works, it's a lovely match for my NS10s.

 

[LTig]

The switches in both my K&H O300D which select between normal input and external crossover had the same problem (the only one they developed in 19 years, knock on wood).