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MVS 2 Slot Repair Help

ack said:
Just so there is no confusion. When I say B7 and B8 I'm talking about the location of the chips on the board and not pins on the chips. If you look above the middle part of the jamma connector there are letter A to S going up the board, and at the bottom/top of the board are numbers 1 to 11. So B8 is the chip at row B, column 8, which is the 74AS245 on the right.

For your issue you we need to work backwards from pin 19 to figure out why its stuck high. As you showed pin 19 connects to that 74AS08 on pin 6.

Next steps will be to logic probe pins 4 and 5 on the 74AS08 and see what they are doing. Pin 6 should only be high when pin 4 and 5 are high.
  • If pin 4 or 5 has faint pulsing, but there isn't faint pulsing on pin 6 it would point to the 74AS08 being bad (I doubt this is whats happening)
  • if either pin 4 or 5 is floating that points to a broken trace
  • if both pin 4 and 5 are also stuck high you need to take another step backwards and track down why
    • You show that pin 4 and pin 1 are connected together, so seems unlikely you need to look there or the issue would also be effecting the other AS245 too
    • So I would work backwards from pin 5 on the 74AS08 to see where thats coming from and see if that IC is working right
Click to expand...
Thank you very much for your patience and persistence in helping me.

The Flux arrived and I replaced the ZMC2 in the 2slot MV2F. it turned out well, it works well in one of the slots. The other is already showing improvement.

A little later I will start checking the levels on a 4slot board.
 

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ack said:
Just so there is no confusion. When I say B7 and B8 I'm talking about the location of the chips on the board and not pins on the chips. If you look above the middle part of the jamma connector there are letter A to S going up the board, and at the bottom/top of the board are numbers 1 to 11. So B8 is the chip at row B, column 8, which is the 74AS245 on the right.

For your issue you we need to work backwards from pin 19 to figure out why its stuck high. As you showed pin 19 connects to that 74AS08 on pin 6.

Next steps will be to logic probe pins 4 and 5 on the 74AS08 and see what they are doing. Pin 6 should only be high when pin 4 and 5 are high.
  • If pin 4 or 5 has faint pulsing, but there isn't faint pulsing on pin 6 it would point to the 74AS08 being bad (I doubt this is whats happening)
  • if either pin 4 or 5 is floating that points to a broken trace
  • if both pin 4 and 5 are also stuck high you need to take another step backwards and track down why
    • You show that pin 4 and pin 1 are connected together, so seems unlikely you need to look there or the issue would also be effecting the other AS245 too
    • So I would work backwards from pin 5 on the 74AS08 to see where thats coming from and see if that IC is working right
Click to expand...
I made a video on the link: https://youtu.be/EltPhFWto_o
green wire 7408 4 pin
lemon wire 7408 5 pin
black wire : 7408 6 pin
 
can you compare those to pins 1 2 3 on the 7408?
 
I'm a little confused. It looks like both output pins (3 and 6) of the 74AS08 have faint pulsing? But pin 6 on it is connected to pin 19 of the 74AS245 at B8, which you said wasnt pulsing?

It looks like pin 5 on the 74AS08 comes from pin 7 on 74AS244 @ C11. Can you logic probe pin 13 on that 244 and see what its doing, I wouldn't be surprised if its floating. There is a ton of corrosion on and near the 244.
 
ack said:
I'm a little confused. It looks like both output pins (3 and 6) of the 74AS08 have faint pulsing? But pin 6 on it is connected to pin 19 of the 74AS245 at B8, which you said wasnt pulsing?

It looks like pin 5 on the 74AS08 comes from pin 7 on 74AS244 @ C11. Can you logic probe pin 13 on that 244 and see what its doing, I wouldn't be surprised if its floating. There is a ton of corrosion on and near the 244.
Click to expand...
74AS244 @ C11. I checked pin 13 with logic probe. it doesn't show anything. I measure 1.8V with a multimeter between GND and pin 13
 
r67055 said:
74AS244 @ C11. I checked pin 13 with logic probe. it doesn't show anything. I measure 1.8V with a multimeter between GND and pin 13
Click to expand...
is it possible that 74AS244 @ C11 pin 13 goes to SNK CORP PRO-C0 3pin? and K2 74LS08 pin 1
 
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Yes thats what I see on mine. PRO-C0 3pin and K2 74LS08 pin 1.
 
fixing the trace to pin 13 on 72AS244 @ C11 fix your crosshatch issue?
 
glad the 4 slot is working.

For the 2 slot issue. The flow of sprite data is

slots -> 2xNEO-257 (to the left of the slots) -> NEO-ZMC2 -> NEO-B1

The purpose of the NEO-257's to pick which slot's sprite data should get passed to the NEO-ZMC2. Since the issue is only effecting slot 2 it implies the issue is not the NEO-ZMC2 or NEO-B1. The first thing I would suggest is checking continuity between the sprite data lines (CR1-CR31) on the CHA slot and the NEO-257 chips.

I'm pretty sure the pinout for the MV2F for those NEO-257's will be the same as the MV2B as seen on devwiki below

https://wiki.neogeodev.org/index.php?title=NEO-257
 
ack said:
glad the 4 slot is working.

For the 2 slot issue. The flow of sprite data is

slots -> 2xNEO-257 (to the left of the slots) -> NEO-ZMC2 -> NEO-B1

The purpose of the NEO-257's to pick which slot's sprite data should get passed to the NEO-ZMC2. Since the issue is only effecting slot 2 it implies the issue is not the NEO-ZMC2 or NEO-B1. The first thing I would suggest is checking continuity between the sprite data lines (CR1-CR31) on the CHA slot and the NEO-257 chips.

I'm pretty sure the pinout for the MV2F for those NEO-257's will be the same as the MV2B as seen on devwiki below

https://wiki.neogeodev.org/index.php?title=NEO-257
Click to expand...
I managed to find the wrong line. The card started up fine, but the sound is bad, but the sound is bad only in the 2nd slot. The sound works flawlessly in slot 1. If both cards are included, the card in the 2nd slot makes small graphic errors. can be seen in the video.
https://youtu.be/v4ZGXRQw4ro
 
I've not seen that type of graphics glitch before. Does it happen with other games?

Does bad sound mean no sound? or wrong/weird sounds are playing? if you are on slot 2 game and tell the bios to switch to slot 1, does slot 1 sound become broken too?
 
ack said:
I've not seen that type of graphics glitch before. Does it happen with other games?

Does bad sound mean no sound? or wrong/weird sounds are playing? if you are on slot 2 game and tell the bios to switch to slot 1, does slot 1 sound become broken too?
Click to expand...
can you watch the video?
if both cards are included, the bios switches from time to time between 1-2 cards. the sound of the 1 card never deteriorates. even if there is only 1 card in it, only the sound of the 2 cards inserted in the slot is bad. the sound is so bad that certain sounds are distorted and very loud. there are sounds that are quiet and distorted.
 
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sorry I had the volume down on my computer and was only looking at the graphics. It sounds like its playing the right sounds, just distorted. I believe this will point to a PCM data path issue from the carts prog board.

Based on this page

https://wiki.neogeodev.org/index.php?title=MV2F#V_ROM_.2F_YM2610_access

It sounds like the PCM data path is: slots -> NEO-G0 @ K9 -> YM2610. With the NEO-G0 picking which slot's data to pass along. Since its only effecting slot 2, I would check continuity between slot 2's SDRAD0-SDRAD7, SDPAD0-SDPAD7 pins to the NEO-G0.
 
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