I've taken photos off preamp section.
Don't know why all connectors are hot glued, had to be careful not to break smth
I did 5 pictures:
1. Amp backplate
2. Whole preamp board
3. Top preamp section
4. Middle preamp section
5. Bot preamp section
Picture 4 Con1 is going to amp board.
On picture 5 Con2 is connection to volume control on top of the subwoofer box.
Parts on Picture3 (above R8) seem like flux residue, but I'm not sure if that was being resoldered - on the backplate in the same position is crossover control (40Hz -120Hz)
Similar for bottom of Picture 4 and top of Picture 5 (above Q5) - on the backplate in the same position is Auto On switch (On, Off, 12V trigger).
Analyzing the pictures i see that similar connections (from top to bottom):
1. Right from C36 (Picture 3 and 4) two joints are soldered together.
2. Above R13 (Picture 3 and 4) two joints are soldered together
3. Left from R45 (Picture 4) two joints are soldered together
4. Above R79 and R80 (Picture 4) two joints are soldered together
5. Below R79 and R80 (bottom of picture 4) and above Q5 (top of picture 5) seems like these two joints are not soldered together (there is also some flux residue I think).
If you need higher resolution images, they are on:
https://imgur.com/a/cStiKlLI think I can't do better pictures with my mobile phone in this lighting.
If you need better resolution/clarity I can try borrowing Nikon from my parents.
What should I do next?