Hello everyone, after several weeks of searching on the internet to find a solution to repair my S750, I came across this forum that changed my life.

Thanks to this I was able to repair my S750 which hadn't given any sign of life for a few years.

Many thanks to Lex and MichelD!

I followed all the advice and replaced all the capacitors on the PSU board which allowed me to bring my S750 back to life.
I will now replace all the components of the AMP and Audio card.

However while trying to remove the glue from the audio card, I broke the C28 capacitor.
I would like to know if this will affect the S750's operation? and I would also like to replace it, could someone please let me know its value (Farads)?

Anyway one thing is for sure I'm not going to try to remove the damn glue from the audio card anymore, I don't want to do any more damage.

Thank you very much for creating and feeding this topic.

thank you for your answer and your help MichalD. i don't think i have enough courage to test the audio board with the missing C28 capacitor.

Regarding the C28 value measurement,no problem I'll wait, anyway I'll receive the capacitors from the Amp and audio board this Monday, so I'll have something to do in the meantime.

as for the glue, I think you're right and I don't like to see this brown thing on the board, so I'm going to totally remove it by taking even more precautions.

I finally removed all the glue from the audio card and replaced all the components , this during with all the precautions taken, I broke a second C85 capacitor so I would also like to have its value if possible. Thanks in advance.

hello thank you very much for your help MichalD . i'm going to go buy and replace these two capacitors with 10nF as soon as possible. i would like to know if they are non-polarized capacitors? i'm going to replace them with conventional (not SMD) capacitors, that shouldn't be a problem, i think.

C28...10,357 nF...so it will be 10nF nominal.
C85...10,732 nF...si it will be 10nF nominal too

What do you think about the voltage ? I think 16V is good.

Thank you for your advice
so I'm in the middle of moving, and I'd like to refurbish this s750 before I move into my new home. This morning I received and immediately soldered the broken components of the audio board.
So here is the long awaited moment, the end of this subwoofer update. I put everything back in place for a test to check that everything is ok.
The PSU part is working fine, when I turned on the power to green led from the pod, I heard a high-pitched whistling noise coming from the amp board that feeds the woofer, as if a component had a leak. I turned it off immediatly. I checked if there was something visible, I didn't notice anything visible. I turned it on a second time to try to identify where the noise was coming from. and the one buzz can be heard on the board and in the woofer but no music comes out. before the update of the audio board and the amp everything is fine and now I don't understand anything anymore. What can I do?

Do you have checked the voltages of PSU?
Yes all voltages is ok

If you disconnect audio processing board flat grey wire from woofer amp board will the buzzing sound dissapear?
Yes i dont have any buzz
the buzz is heard only on the woofer board and it is heard on all outputs of the woofer board. whether a signal is input or not.

What for the other AMP board it is working properly?
Yes other amp board work great

I'll try to check for shorts circuit or bad solder.