DD2 sound fix

[jonhughes]

Bought a DD2 PCB with sound problems.

The PCB played the background music fine but appeared to play random samples of the sound FX or all samples of the sound FX in one go.

Noticed a lot of loose caps around the board and sound section but replacing these made no difference.

Did some background reading on the PCB and read that the sound FX was controlled by a surface mounted M6295 (OKI chip). Found a scrap MK PCB with one on it so desoldered both SMCs and replaced the suspect one. The MK chip was worse than the one on the board. No sound FX now and background music now struggling. Is this why this MK soundboard was scrapped?

Didn’t have another one spare so ordered 3 from China. Replaced the M6295 and now all sound FX and background music are fully restored.



And in the naughty corner we have:

 

[Retroman839]

Bought a DD2 PCB with sound problems.

The PCB played the background music fine but appeared to play random samples of the sound FX or all samples of the sound FX in one go.

Noticed a lot of loose caps around the board and sound section but replacing these made no difference.

Did some background reading on the PCB and read that the sound FX was controlled by a surface mounted M6295 (OKI chip). Found a scrap MK PCB with one on it so desoldered both SMCs and replaced the suspect one. The MK chip was worse than the one on the board. No sound FX now and background music now struggling. Is this why this MK soundboard was scrapped?

Didn’t have another one spare so ordered 3 from China. Replaced the M6295 and now all sound FX and background music are fully restored.

View attachment 31881

And in the naughty corner we have:

View attachment 31882

Great that you knew that the second sound fx chip was also faulty …

I would have struggled thinking 🤔
What is going on ?

And have you tried one of your chips from China on your scrap mk board yet ?

 

[jonhughes]

The MK soundboard really is scrap, I traded something for it. Won’t be populating it back up, not worth the time and effort.

 

[TheDaddy]

Nice repair mate !! These OKI's are a mare. I have some spare and a few boards with type of issue I need to look at. I have a Thunder Hoop thats all over the place , But I am thinking it may be the Addressing killing that.

Dave.