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G-9000DB Distorted sound on left channel (Solved)

Thanks Paul,
I'm done with the right side, those Bourns are really amazing. moving on to the left side.

Fluke.jpg 2806 Right.jpg 2808 Right.jpg 2814 Right.jpg
 
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This model does not have the flame proof resistors that go bad, but does have normal resistors on the driver boards that go bad. Check R23, R24, R31, R32, R35, R36.
 
Thank you Warren! Can I assume that since I got perfect Bias on the Right side, that all is fine with that sides' resistors?
 
I see 2 fuse resistors on each board, on your pics. They are the smaller, raised up off the board resistors, and are 150 ohm. They will need replaced. Some of these have the fuse resistors, most do not.
 
Thanks Paul,
A37042B5-C272-4510-815C-C054FE86265C.jpeg Do you mean C01 & C05? (The two in the middle of my photo) Can you please recommend a Mouser or Digikey model number I should order?
 
No no, leave those alone. I am talking about the resistors. I circled them in the attachment. Replace with 150 ohm 1/4 or 1/2 watt metal film types:
 

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You forgot to replace a capacitor dude :) I circled it, and it should be the same value as the one I underlined.
 

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I know! I noticed that while working on the left side, I was like “strange, there are 5 here and only 4 on the right?:idea:” Pulled the right one out and replaced it. Good catch! Thank you. I’m just about finished with the left side only need to solder the two 100v 4.7uF on 2814 and I can finally test the bad side. It had a bias of 0.00 :no:.

I’ll order these Resistors, these boards are easy access. should they be fuse resistors?
 
Metal film. You can put fusibles back in there if you want, but I wouldn't. Just something that wont catch on fire is all you need here, and metal film will do nicely. You can check the ones that are in there in circuit. I bet they are way high or even open, making your test pointless until they are changed.
 
ManyMoonsAudio said:
Metal film. You can put fusibles back in there if you want, but I wouldn't. Just something that wont catch on fire is all you need here, and metal film will do nicely. You can check the ones that are in there in circuit. I bet they are way high or even open, making your test pointless until they are changed.
Click to expand...
157ohm and 153ohm on the left driver. Looks fine but I’ll replace them just as well!

8AF67CB1-85C6-4574-8AD1-3A4705A3350A.jpeg
 
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Ok, after reinstalling the left channel driver board, I still get distortion from time to time. New issue started, protection kicks in and goes away from time to time. Bias is not stable and jumps from 17 to 0 to 10 to 0 randomly.
I removed this driver board and put instead the right channel driver board. Issue gone. So I assume the problem is with the driver board itself. Capacitors and trim pots have been replaced. Any suggestions?
 
Ok, all resistors measure correctly, including the ones Warren recommended I check (they were on the other side of the metal wall).
But ZD02 measured 0L in both direction. ZD01 measured properly. Both tested outside the board.
Would that cause my issue?
 
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Golanr said:
Ok, all resistors measure correctly, including the ones Warren recommended I check (they were on the other side of the metal wall).
But ZD02 measured 0L in both direction. ZD01 measured properly. Both tested outside the board.
Would that cause my issue?
Click to expand...
I would say so since voltage is not passing where it should be since the zener registers as open
 
Thanks, all parts ordered. (Zener and replacement for fuse resistors as recommended by Paul) I’ll update once they are installed
 
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Strange that Zener is open, but if it is, that is where you start for sure. Check it again, making sure you got good connection with your leads.

Symptom sounds like you have a transistor losing conduction. Driver or pre-driver most likely.
 
ManyMoonsAudio said:
Strange that Zener is open, but if it is, that is where you start for sure. Check it again, making sure you got good connection with your leads.

Symptom sounds like you have a transistor losing conduction. Driver or pre-driver most likely.
Click to expand...
Thanks Paul!
I completely removed the Zener from the 2806 Driver board to test. I also thought that maybe I don't have good connection and cleaned the metal wire until it was nice and shiny. In any case, I'll replace it and few other known resistors and fuse resistors, can't hurt :)
Pre-Driver? Can you please help me here and be more specific as to what board I should be looking at? Remember, I took the right side Driver Board and put it instead of the "bad" left side driver board. Bias was perfect and there was no distortion.
 
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