Disk System RAM adapter-sound too low

[jonasanu]

Hi,

i didnt use my FDS while and when i power it yesterday, sound from FDS RAM is suddenly too low, i can barely hear it 
With normal famicom game cartridge its sounds just fine.
I did recap 3 electrolytics capacitor in RAM adapter, but still no luck.
Is anybody know what to check next?
Im not really so technically skilled guy.
Cheers
!

[zmaster18]

I think I had this issue once or twice... I forget how I fixed it but I'm pretty sure it was a dirty pin for sound on the RAM adapter, as well as a capacitor being loose. Try reflowing solder for the pin which outputs the sound. I think there is one pin for regular Famicom sound, and another pin for FM sound, so make sure to check both 

[jonasanu]

Thanx a lot, i try it today!
Could you please direct me, which pins are responsible for sound as i cant find FDS RAM schematics anywhere

[Sydsydsyd]

Hi jonasanu nice to meet you.
Here you can check technical details https://nesdev.com/FDS%20technical%20reference.txt
Hope you can solve your issue 

[P]

Cartridge connector pinout: https://wiki.nesdev.com/w/index.php/Cartridge_connector
2C33 pinout: https://wiki.nesdev.com/w/index.php/RP2C33_pinout

The audio from the APU enters the RAM Adapter via cartridge pin 45 and after being mixed with the expansion audio it goes out again on cartridge pin 46. I guess you should be able to trace it from those.

The expansion audio seems to come from pin 54 on the 2C33 chip.

[jonasanu]

So i found one one of ceramic capacitors is bad, however i forgot to mention, that i did connect a Famicom through RGB switch, so it seems there is something wrong on switch side, becouse when i connect Famicom directly to TV sound is just fine....