2-slot sound problem

[Adamaki]

I keep seeing this problem all the time recently but now it's happened to me.

I put a new game in my 2-slot today and the sound effects are all crackly. The music is fine. I tried swapping games and it's only slot 1 that is bad with all games and slot 2 works fine. I've tried cleaning the slot but it's not easy cleaning the contacts right inside.

Anyone got any ideas? I was wondering if leaving the games in the slots when it's not being used would loosen the contacts. Although surely that would happen all the time when an mvs is being used in an arcade and they still seem to work ok.

Anyway, any help getting it fixed would be much appreciated.

 

[chris1]

Try cleaning the slots on the mobo with the finer side of a cardboard nail file..then blow out all the dust.(as I did/do)
Then use alcohol with a Q-tip to get the dirst off...(let dry)

 

[Adamaki]

Yeah I'll give it a go. I've got some really fine wet and dry paper so I'll try getting that between the contacts. The Q-tips are too wide to fit between the contacts though.

I'm sure it's only bad contacts as the other slot works fine.

 

[chris1]

Yeah I'll give it a go. I've got some really fine wet and dry paper so I'll try getting that between the contacts. The Q-tips are too wide to fit between the contacts though.

I'm sure it's only bad contacts as the other slot works fine.

You could also use some of that Contact cleaner spray...I had some that I bought out of Radio Shack and it would dry in seconds.
Main thing is having everything dry before firing it up..

 

[Adamaki]

Well I gave the contacts a rub down with fine wet or dry paper and the slot now works with my blazing star cart which is quite tight, but it still doesn't work with any other cart. I guess I need to work on it some more, but I was just wondering if anyone knows which pins are used for sound data? Then I would know which pins to concentrate on cleaning well.

 

[ttooddddyy]

http://www.arcademike.com/pinout/Mvs cart.txt

 

[Adamaki]

Cheers toddy I'll have to study it and figure out which pins are causing the problem. Haven't got time now, just off to Tunisia for 2 weeks Later peeps!

 

[Adamaki]

I finally got round to working on my dirty slot ( ) last night! I had a look at that pinout diagram that toddy posted but it's not that useful. It says all the sound roms are on CTRG2 but that still leaves me 120 contacts that could be causing the problem. Does anyone know which of those pins are for sound?

Anyway I gave all the contacts on CTRG2 a good rub down with wet and dry paper again and checked all the springs to make sure they're all working but it still hasn't solved the sound problem.

Is there any chance there could be something else causing the problem?

I was wondering if it's possible to check individual contacts for power using a multimeter?

 

[Adamaki]

Bump.

 

[ttooddddyy]

The toothbrush and contact cleaner method works fine for me
http://www.hardmvs.com/html/slotCleaning.htm

 

[neo_X7]

The toothbrush and contact cleaner method works fine for me
http://www.hardmvs.com/html/slotCleaning.htm

Does Radio Shack still even carry that?

 

[Adamaki]

Does Radio Shack still even carry that?

Doesn't really matter to me if they do because I'm in the UK!

I'm beginning to think it's not dirty contacts anyway because:

a) all games worked fine then suddenly sound was crackly on all games.

b) If it was a gradual build up of dirt on the contacts then maybe some games would go crackly but a quick clean of the contacts would fix it. I've cleaned all the contacts extensively and the sound is still crackly.

I think there could be a problem with the traces from the cart slot. Maybe one has become damaged or bridged. If only someone knew which pins are used to carry the sound data I would know where to look...

Any thoughts?

 

[ttooddddyy]

assume nothing and expect the unexpected

 

[neo_X7]

Any thoughts?

I am sure that you have but have you checked the Jamma harness for loose wires?

 

[Adamaki]

I am sure that you have but have you checked the Jamma harness for loose wires?

I don't have a Jamma harness. It's a consolised unit so the wires are soldered directly to the pcb. Anyway it's only slot 1 which has dodgy sound and slot 2 works fine which makes me think the problem is with the slot or the surrounding traces.

Nice advice toddy! I think I'm going to get the multimeter out and start testing the contacts.