Metal Slug 2 and X with sound issues

I wonder if anyone has any ideas about what could be wrong and if it's fixable.

I have two MSX carts and at least one MS2 cart with distorted sound. Like certain parts of the sound is missing. They all sound high pitched and noisy - like all low frequency sounds are gone.

I've been through the obvious steps - cleaning, checking soldering points and so on but can't spot anything odd.

Here are pics of the MCX PCB's: http://newastrocity.wordpress.com/metal-slug-x-with-sound-issues/

I'll try to get a video clip of one of the games playing tomorrow.

Any help would be highly appreciated

Have you tried using an eraser on the edge connector? Maybe some metal polish on it if that doesn't work.

Yup, tried both eraser and metal polish

Here's the first MSX live:

And the second:

On toshiba mask roms, one of the tells that a rom has gone bad is that the middle of the chip will have a brownish square.

You could tell that from the pics? If so I must be blind. Any chance on replacing a faulty sound chip?

Stompp said:

You could tell that from the pics? If so I must be blind. Any chance on replacing a faulty sound chip?

Click to expand...

No, just in general. But take a good look at the prog board.

Can't really spot brownish squares on any of the chips. I'll get hires pics of the boards and maybe someone with a better eye can spot them.

Is it possible to exchange a faulty sound ROM for an EPROM and if so, where might one find the code to use?

In some cases you can easily replace an original mask ROM with an EPROM and in some cases you cannot. If the original mask ROM is 64Mbit then that is a problem because the largest EPROM size is 32Mbit. Also I think some carts use Amtel mask ROMs that have some security measure to prevent a simple EPROM swap (I think it is only on the P1 ROM though). Since your issue is with the sound (V ROMs and/or M ROM) that should not be an issue.

I try to only replace ROMs as a last resort after I have ruled out everything else. You can learn a lot about the problem with a logic probe. It may be an issue with one of the 74LS chips or the NEO-PCM. Those are easier to replace than a ROM.

Hi,

Stompp said:

Is it possible to exchange a faulty sound ROM for an EPROM and if so, where might one find the code to use?

Click to expand...

Sure, for M1 you can use TI TMS27c010A on both games. For V roms you can use MX29L3211.

Saludos

Hmm, logic probe sound kinda Greek to me. Any pointers on where I can figure out more on the subject?