Yamaha DSP-AX2 - no sound from center in DSP-mode

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I bought a Yamaha DSP-AX2 which won't output any sound to the center speaker. So question is, can it be repaired with smaller efforts?

Facts:

  1. It plays fine on all main channels.
  2. It plays fine on front and rear channels
  3. No sound on center channel when it's routed through the DSP
  4. Center channel plays just fine when using the "6 channel input mode" and plug the source to the center directly. However, no adjustments can be made to the sound, not even bass or treble.
  5. I've done the clear presets as described on page (pdf page) 22 in the service manual before.
  6. When doing the output test on all speakers, all work fine but the center. However, when I turn the volume to maximum, I can faintly hear the test noise on the center channel. And once again, as I've pointed out before, the center speaker plays fine when I use it in "6 channel input mode" and connect the audio source to the center input.
  7. I've opened the amp and cleaned it with compressed air, checked for cold solder joints on each transistor (2 per channel) on the main board, they seem fine.
I'm not very familiar with troubleshooting electronics, even though I can solder and do simpler measurements with a multimeter.


Is there something wrong with the DSP board?
Is there some "hard reset" which clears EVERYTHING and resetting to factory defaults? I can't find anything like that in the service manual, am I looking for the wrong words?



I'm not familiar with abbreviated technical words :(, at least not yet before I've learned, so please write the full words as much as possible, thanks guys! :)


Service manual for DSP-AX2
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Thanks! :)
Martin
 
Are you 100% sure the centre mode is not set to Phantom?

I don't know actually. I bought it used, like this. When I search the pdf manual for the word "phantom", nothing comes up? What is that and how do I change that setting on the AX2?

Btw, if there's a Phantom mode set as you say, does it make the center test tone silent to? Because there's no sound from the center in test mode either.
 
Check the speaker settings in setup to ensure centre is not set as none. Should be small or large. I'm not familiar with this amp, but that's how the HT amps are setup, none/small/large are the options.

Other than that, reset the amp to factory settings.
 
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It was set to large before, I've tried it on small. No difference.
I've done the only "reset" I could find in the service manual, but it actually rather seems to be clearing some dsp settings the user may have done.
I've still not find a real reset to factory defaults or hard reset or something like that. And I've searched the net like a maniac.

What's weird though is that I get sound on the center when connecting to the Center-IN on the 6-channel inputs and using the 6-channel mode. So the amp portion for the center seems to work. Should be something faulty with DSP I guess?
 
According to the DSP-AX2 user manual, centre channel is not available on HiFi DSPs. Check the centre channel operation on movie DSPs.

DSP-AX2 - Yamaha Downloads Other European Countries

I couldn't find an overall factory reset in the manual but new Yamaha HT amps have a Initilize setting via a panel button sequence for advanced menu settings.
 

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Test tones can be presumed to be digitally generated. Hence those won't work if the center channel out of the DSP section doesn't operate.

Check DC voltage on both output pins of opamp IC527 for a start, and make sure the signal actually makes it from R689 to R590 near IC512 on the Function board (continuity). It could still be a number of things, but possibilities are finite.
 
Test tones can be presumed to be digitally generated. Hence those won't work if the center channel out of the DSP section doesn't operate.

Check DC voltage on both output pins of opamp IC527 for a start, and make sure the signal actually makes it from R689 to R590 near IC512 on the Function board (continuity). It could still be a number of things, but possibilities are finite.

Thanks! I'll do this asap and get back with the results.
 
I'm using analog input via RCA just to test. But the DSP center should work also, not only the rest of the DSP channels. Not even the test tone works for the center. But the center amp isn't blown as the center works fine when using the center in on the 6-channel input. However then I can't even adjust bass or treble on the center, and no DSP.

Not had time to pick it apart to check DC voltages due to cancer in the family unfortunately. I'll get back as soon as I get time.
 
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