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2245 One Channel Low and Distorted

I pulled H405 and it seems to test good on my dmm cap tester but I'll swap it with the one on the other channel and see if the problem follows.

If that doesn't do it I'll start putting in replacement caps. I think I have some on hand.

Thank you jd3rdcoast for all your help, and I dig your eclipse photo.

Gary
 
The swap H405/H406 swap made no difference. In fact to my surprise, the aux input played through to the headphones on both channels with H406 off the board entirely.

Fresh day, fresh thought. With input through the Main In everything sounds fine. Pre Out to another amp introduces the bad audio. To my understanding this rules out the P750 boards.

This is what lead me to the tone board which is where I found the voltage problem and traced the signal to find the distortion.
 
Thanks Gary. Did you mean diode checker? You can test a BJT like two separate diodes. There is a thread here somewhere on how to do that or you can google it. Although may not always show bad unless dead short between C-E, B-E or B-C.
Throwing up the circuit if needed.

2245-P400_Tone.JPG
 
grey_beard said:
The swap H405/H406 swap made no difference. In fact to my surprise, the aux input played through to the headphones on both channels with H406 off the board entirely.

Fresh day, fresh thought. With input through the Main In everything sounds fine. Pre Out to another amp introduces the bad audio. To my understanding this rules out the P750 boards.

This is what lead me to the tone board which is where I found the voltage problem and traced the signal to find the distortion.
Click to expand...
Input to Main-In, Bypasses the Preamp/Tone section. Output from Pre-Out bypasses the Amp boards. Your experience with the Headphone via AUX in is a bit confusing. You may have to trace the signal paths on the schematic in and out of the headphone jack for an answer.
 
I just tested the transistor for a dead short with my dmm as you mentioned above then switched H405 and H406 to confirm. I was totally surprised that I had signal to the headphones without H406 on the board at all. Something is surely amiss with that.

Now I am wondering about bypassing the tone board for testing just to be sure that the issue resides there.

I have started pulling the caps off the tone board for testing. C401, 403, 405, and 407 all test good within a few percent of stated value.
 
I'm late to the party but I've had bad caps on the tone board do this exact thing. And here is the issue.. they tested fine on the bench but couldn't pass audio worth a damn. I had two in particular that were on the volume control for R/L channel and it was my R channel giving me fits. I end up replacing them with new films which solved the issue.
 
Same deal for me with aged caps. DMM check shows capacitance good but more often than not, when exposed to the MUCH higher voltages of the actual circuit, they become leaky and sound like a$$.

Case in point is my current resto-mod project, a Leak Delta 30. The amp worked and sounded OK with original caps but after pulling them (three 1000uf and one 2500uf all for smoothing ) I found they had all spilled their guts and bubbled up the plastic can tops.
 
Okay. Thanks, guys. Looks like I'm in for a recap on this one. I've got the caps off already so there's no sense putting them back on.
 
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