Stagg sms12p audio amp has water damage

[edugimeno]

Hi! My friend just brought this audio amplifier/speaker fro his music band saying they realized its got no sound. Led powers up but there no sound at all
I opened it and found 3 board. 2 of them are for input plugs and potentiometers, and the other larger board has the amplifiers for 2 large speakers that it drives
There's also a large toroid transformer that feeds a lower voltage to the first 2 boards and a larger voltaje (36x2 rectified close to 100v) to the power board. The power board has the plugs for both speakers
There is only one signal wire connecting the first boards with the power board so I guess all sound has to enter at this plug. I applied signal to this plug and there absolutely nothing at the speakers.
I realized this amp must have been stored at a wet environment as the board has lots of traces of water
I have taken some close up pics of the water traces
Would I expect some real damage to the boards or just by removing the salt residue would I have any result?
Is there any trick you can share to remove the water salt from the board?
Any other hint on how to start?

Thanks in advance

[CapLeaker]

You put signal into the input and got no output on the speakers. No DC on the speakers, the clip LED is OFF? Does it have bi amp (like one PA for the highs and another one for the woofer? Put a signal into the input, then poke around with the oscilloscope in DC mode and see where you loose it. Maybe it goes through an opamp and there is nothing coming out of it's output (That TL084CN is a candidate for example). Could be also that a voltage is missing somewhere or a broken trace(s). First off clean the crud off the boards with 99% rubbing alcohol and a toothbrush etc. The other boards have voltage regulators too, like the 7912 (-12V). Maybe upload the pics of the other boards.

[edugimeno]

Hi, thanks! Some answers.
The clip led is off all the time. Yes its a dual amplifier, it looks like the 4 large transistors at one side (bottom side of board) feed tha large sobwoofer, and the other 2 transistors at the other side (still bottom side of board) feed the medium size speaker
I didn't spend any time at all for now with the other boards at there only one signal wire linking them to the main power board, so this is the only way the sound has to enter the power board, and applying a signal on this wire should get some sound if the power board was fine. Maybe if I fix the power board and still get not sound I will have to pay attention to the other boards...
Ok I am away from the plae where I have it but will try to clean with alcohol next weekend and also see whats going on around the OP AMP IC. An schematic would help a lot to trace the signal throughout this board...

Thanks!