Mega Drive doesn't play certain sounds in certain games

Hi

My Sega Mega Drive has a problem that causes it to not play certain sounds in certain games:

On my Mega Games 2 cartridge (3 games in 1: Golden Axe, Streets of Rage and the Godzilla-free version of The Revenge of Shinobi), the character select chime in Golden Axe can't be heard every time you choose a character. Also, if you return to the game select menu by pressing the reset button while playing Golden Axe, only half of the beats can be heard in the music heard on it! (yet ALL the beats in that game select screen's music CAN be heard if you are there after having turned the console on or resetted back to it while playing Streets of Rage or Shinobi)

In Micro Machines 2, any amount of sound in any part of the game can disappear at any time. You may either lose some (but not all of) the vehicle sounds during gameplay, or lose the music in the menu screen you're on. You can never tell if/when this will happen.

In The Smurfs, although the highlighter chime can be heard whichever direction you move it on any other menu screen (language select, main menu, options), it cannot be heard if moving up on the password screen.

I have no idea what could be the cause of this problem. I don't have another Mega Drive to test the games themselves on, yet some guys at the computer shop near where I live could hear those sounds no trouble when they tested them on their Amstrad Mega PC (I asked them to try and find what could be the cause of my console's fault, but they weren't successful). Before, I had the same "half the beats on game select music missing" problem with my Mega Games 3 cartridge if one were to reset back to said menu while playing Super Thunder Blade, but following my dad's attempt at cleaning the Mega Drive's cartridge slot, THAT problem was fixed for THAT cartridge. A retro game store an hour's drive from where I live looked at my console and found some wobbly teeth in the cartridge slot, and reckon the cartridge slot could be the problem.

I don't know any other game console tech wizards in my country (the UK), and I don't have a Mega Drive test cartridge or anything, but I really would like this problem of mine fixed! The Mega Drive is my ALL TIME FAVORITE console! Wii Virtual Console is NOT an acceptable substitute!

I will do a video for YouTube regarding my troublesome console this weekend.

 

Well, for a start, you've got the 6 channel YM2612 handling FM and PCM sound, then the 4 channel SN76489 as a PSG. So work out which is at fault for starters.

It's more a home project, really - it wouldn't be worth having a professional repair it, considering the low cost of a replacement console.

 

I have a similar issue with my Mega Drive 1, but the sound doesn't seem to want to work properly at all in most instances. PCM sound is glitchy and FM sound only works at all really in Sonic 1.

Given that most of what it gives out is beeps im inclined to think that the PSG is fine, the YM2612 is the issue, but I don't know yet.

 

I had an issue like this occur on a MD1 which I modded for someone. Tested and tested and tested and never got to the route of the problem. It'll not cost much to buy another one, they're pretty cheap on eBay.

 

Here is my video detailing the problem:

http://www.youtube.com/watch?v=S5zUA1qFXQI

 

The SN76489 is integrated into the VDP on the Genesis/MD so you'd actually be dealing with a VDP issue rather than with a separate chip.

 

I'd bet it's a case of bad caps.