It's actually the speaker on the right side of the tv that causes the noise to occur, when I cover it with something it dissappears. So I suppose the magnet inside the speaker causes some electromagnetic interference on the audio, is that possible ?
That is possible. That also means that the audio cicuitry inside your cartridge is not shielded. You can try to wrap the cartridge in aluminium foil and ground it to some metal part of the msx. If the interference goes away. Its time for some serious internal shielding.
Try pin 49 as well. Maybe your MSX is picking up the interference.
@luppie : I was curious about this. So I downloaded Eagle 7.1.0 and Your schematics. Wow!
Great job! I would like (time letting me) to create a Konami-size cartridge with a i8254 timer to add a timer peripheral to MSX for every real-time application, or - maybe - for a music tracker.
Just a feedback note: when I open board view it gives an error.
EAGLE update report
Date: 11/10/2014 20:28:38
File: C:/Users/user/Documents/eagle/FM-Pak/fmpak.sch
An error occurred while parsing the intermediate XML file.
The XML file has been loaded into a text editor window as
C:/Users/user/Documents/eagle/FM-Pak/fmpak.rpt.sch
Error:
line 9385, column 6: redefinition of name 'A[0..15]' in tag
