Donkey Kong. Still no sound

[KaBoom1701]

Dude post pics of the boards and take a video of the sounds so we can help.

Something is off

 

[masterfx]

Went through the entire sound board, checked all caps and found 2 with incorrect values. I replaced them and still the siren continues

You need to explain better. We cannot see, hear or know what you are doing. we can only try to provide help with the information provided.

When I asked, you then said:


Here is what I can offer as a suggestion.
There is an optional volume pot VR1 on the Sound pcb that controls the synthesized sound volume relative to the other sounds, that may need adjusting to balance out your level issues for different sounds.

I can't tell what is wrong for the background noise issue, could be many things. Could be a leaky/faulty caps, bad driver not turning the sound on/off properly or other faulty components for that sound.

Edit: I think that sound gets enabled by pulling 6L Pin 12 high. Start there, you can check that pin with a logic probe. After that it is Q4, Q5 and associated passive components. You are looking for what is starting/stopping the sound that is not working properly since the sound actually works the oscillation part comes from 1/2 the NE556).

Went through the entire sound board, checked all caps and found 2 with incorrect values. I replaced them and still the siren continues. I've read many posts about this siren issue after recapping on DK boards and no one has fixed this from what I can see. There has been some well documented info trying to figure this out but no one does. I will say all the sounds are now there and sound normal. I adjusted the pots like you said and it fixed that so thank you. I took notes from your post and others and will try some more things to try and resolve this. If I do, I will be sure to post.

 

[Azure Oz2]

Good to hear it is almost all working correctly. I have a DK4 2 stack in for repair. As soon as I get to it I will post some suggestions on how to narrow down the cause or fix the problem. I have both schematics for 2 stack and 4 stack so can post the relevant component id's for both.
Should be in the week or two.