6 slot audio issues - schematics available? Also slot cleaning.

[telmnstr]

Hello everyone,

I'm working to restore a 6 slot to full operation so it can go on the floor of an awesome arcade.

I recapped the audio section of the PCB and remoted the backup battery, and the startup jingle plays and sounds fine. The one cart that seems to work the best (Aero Fighters 2) has horrible audio, which to me sounds like it's reading the data from the sound roms incorrectly. The carts are hit and miss with lots of errors in the sound and graphics data.

Do schematics exist for the neo-geo boards? I would like to get an idea of how the neo geo cart slot system works. Is it just a matter of switching read enable signals to the cart? Or some sort of buffer enable/disable?

I just saw about the test firmware and I'm going to see if I have any carts to sacrifice. If I have the proper eproms I might burn them tonight.

Another thing I'm curious about - what is the recommended way to clean the cart slots (the PCB side?) This 6 slot system was stored for a long time with the cart slots uncovered and the back door off.

 

[mainman]

Hello everyone,

I'm working to restore a 6 slot to full operation so it can go on the floor of an awesome arcade.

I recapped the audio section of the PCB and remoted the backup battery, and the startup jingle plays and sounds fine. The one cart that seems to work the best (Aero Fighters 2) has horrible audio, which to me sounds like it's reading the data from the sound roms incorrectly. The carts are hit and miss with lots of errors in the sound and graphics data.

Do schematics exist for the neo-geo boards? I would like to get an idea of how the neo geo cart slot system works. Is it just a matter of switching read enable signals to the cart? Or some sort of buffer enable/disable?

I just saw about the test firmware and I'm going to see if I have any carts to sacrifice. If I have the proper eproms I might burn them tonight.

Another thing I'm curious about - what is the recommended way to clean the cart slots (the PCB side?) This 6 slot system was stored for a long time with the cart slots uncovered and the back door off.

Is the cab wired for stereo? How many carts are you running at once? What is the LOADED voltage on the 5 volt bus and what is your PS current rating? Do you by any chance have access to another working 6 slot to isolate the problem if in fact your issue is not a installation error.

 

[shadowkn55]

The only schematics available are the really hard to read copy of the 1F board. Is Aero Fighters 2 the only cart having a sound problem? The top board is basically all bus buffers and some decoders that switch the slot selection. The bottom board has an additional set of bus buffers so it can drive the signals to all 6 slots.

 

[telmnstr]

The only schematics available are the really hard to read copy of the 1F board. Is Aero Fighters 2 the only cart having a sound problem? The top board is basically all bus buffers and some decoders that switch the slot selection. The bottom board has an additional set of bus buffers so it can drive the signals to all 6 slots.

Hello,

No - all other carts (when the audio actually works) show issues with sound as well. There are also graphic sprite issues which indicate bad connectivity of the cart, or issues with the data/address bus coming from the cart.

He has a 2 slot neogeo mini red cab, and a 4 slot cab. The 4 slot has low volume audio which means I will probably end up replacing the audio section capacitors on it at some point. I haven't tested the little 2 slot one (which is for kids) yet but it was working (so I was told.)

I will check the voltages coming off the power supply today. There is a note stuck on it about checking the +12v, but I'm not sure what symptoms it had before I replaced the capacitors.

I'm thinking maybe I'll use rubbing alcohol and a paper towel folded over a paint scraper (the things you use to open mac mini computers) and try to make sure the cart slot is clean.

 

[Xian Xi]

First thing I'd do is wash the top board(even if it doesn't fix the problem, a wash is needed after these many years). Remove the top board and any sockets chips from the top board if any for some reason. Wash it under warm water with a toothbrush and liquid soap, unscented preferred but I've used scented before and had no problems. Scrub the whole board with the toothbrush, around the chips, on the chips and in the slots. Rinse it with warm water. Make sure you get all the soap under the chips out, sometimes there is dirt under them as well. Stand the board vertical the long way on some paper towels and while it's sitting that way use some canned air to get the water out of the slots, under the chips and out of the connectors. Let it drip dry for about 1 hour then hang it outside in the sun for about 2 hours. Depending on where you are, it should be dry after 2 hours. To double check just shoot some under into the same places, if you see water still coming out then hang it for another hour until no more water comes out.

Once you confirm the board is completely dry, use some contact cleaner to clean the slots. I use Deoxit-D5. You can use a thick piece of card board and apply some of the contact cleaner to it and insert and remove it until the cardboard comes out clean, usually it takes two rounds. After that then test the board again and see if the problem still exists.

Doing this will also help identify any corrosion on the board that might have been hidden by dust.