Korg SV-1 with very law signal out.

[DMCHapman]

Hello Everyone, firstthank you for allowingme to be part of this community, i have see this forum is in German language, i hope Englishwill be not a problem. Here is the thing; I am helping my friend to repair a korg sv1 with a very low volumen signal out. I have try almost everything on the range of my knowledge. Replace all capacitor from the output audio board, the valve check all welding, cable and connector in and out, voltage check. So, I feel a little frustrated with that because everything work as normal, the only issue is the low signal out. After a few days of reading and research I found this forum where I hope I can get some help. My last step is going to the audio board and check the electronic component as transistor, Diodes and i have found something i would like to share, specifically on transistor (Q7,Q10) their value is not totally accurate. (Note ; i measures them attached to the board) my question is: can those D transistor be the reason of low signal out? I prefer to ask before I start to remove those tiny things from the board. I will share some photo as reference. Electronic circuit diagram of the part that involve Q7 and Q10 and photo of the components on the board.

 

[electric guillaume]

There are few people in this forum who should be able to help you or at least understand the circuitry.
But I guess the majority here probability won't and that's certainly true for me.
Sorry that I can't help, but nevertheless, welcome.