Black vertical lines and glitches

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
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179
Hey friends

I have another MV-1FZ which will pass all tests on the Diagnostics Bios after I replaced the Fast VRAM.

I have those black vertical lines so I thought it might be LO-ROM related. So I removed my LO-ROM and put a Socket in and tried another LO-ROM with the same results.
I also replaced the LS245 that connects to the LO-ROM and continuity from LO-ROM to LSPC2 and LS245 seems all good.

Along with that I replaced U1, U3, U4, U5, U8, U13 - same results.

I resoldered the Cartridge Socket pins and the LSPC2-A2 and the NEO-B1 along with some other ICs.

Any hints for me from people who has similar issues ?

Thanks have a great sunday
 

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RyuX

Crossed Swords Squire
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Last edited:

ack

Ninja Combat Warrior
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The SFIX rom contains fonts and other baseline graphics. Since your diag bios picture isnt showing the same symptoms I dont think the issue will be the SFIX rom or chips that process the FIXD data. However the FIXD traces also go to that cart slot CHA B39 to B46. I would verify you have continuity to those.
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
The SFIX rom contains fonts and other baseline graphics. Since your diag bios picture isnt showing the same symptoms I dont think the issue will be the SFIX rom or chips that process the FIXD data. However the FIXD traces also go to that cart slot CHA B39 to B46. I would verify you have continuity to those.

In NEO-GEO DEV it says that the S-ROM is included in the SFIX or did I read it incorrectly ?
So which part of the board would be responsible for the S-ROM then ?

I got FIXD0-FIX07 from NEO-B1 to the SFIX ROM.

However when looking around the cart slot I found two broken traces - fixed those and now the output looks a lot more promising already.

So here is what I get now :)
 

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ack

Ninja Combat Warrior
15 Year Member
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The S ROM is the S1 ROM found on CHA boards. Both the S ROM and SFIX ROM share the FIXD0-FIXD7 data bus.
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
The S ROM is the S1 ROM found on CHA boards. Both the S ROM and SFIX ROM share the FIXD0-FIXD7 data bus.

So seeing my newer pictures - any Idea which IC could cause this problem ? or maybe another broken trace hmm
 

ack

Ninja Combat Warrior
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I would guess its the C rom data traces going from the CHA board (CR0-CR31) to NEO-ZMC2 (C0-C31).
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
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I would guess its the C rom data traces going from the CHA board (CR0-CR31) to NEO-ZMC2 (C0-C31).

Thanks I will check those out. Just wondering where do you get the data from ? Is there some kind of resource I can read up on to learn about where/which graphics will be addressed etc ? I would really love to understand more about those things
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Aaaand we got another fix.. thanks for all your help!

Pin 24 was shorted to ground on the NEO-ZMC2 forcing it to a constant LOW state.

So the board had VRAM, Palette RAM Errors and broken traces as well as broken ICs. The Sound and the graphics both did not work but now it is worthy of a Recap as well..

This will be my testboard as I socketed quite a lot of components on this one already.

Have a great evening y'all
 

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ack

Ninja Combat Warrior
15 Year Member
Joined
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Posts
538
Thanks I will check those out. Just wondering where do you get the data from ? Is there some kind of resource I can read up on to learn about where/which graphics will be addressed etc ? I would really love to understand more about those things

Its all from reading stuff on the neogeodev wiki and having encountered the same issues. The wiki has great information on chip pinouts, but I think its lacking in a summary view of the overall flow of data (or I haven't found the page yet).
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Only one more strange thing I noticed.. the games seem to play well without any issues however I have a strange Crosshatch screen (both with stock and unibios)

Any thoughts ?
 

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RyuX

Crossed Swords Squire
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179
Ok.. seems it was my overclock (14.3 mhz) that was causing this.. I changed back to stock clock and now everything is back to normal!
 

Razoola

Divine Hand of the UniBIOS,
Staff member
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What version Unibios were you using when you see that corruption on the crosshatch screen?
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
What version Unibios were you using when you see that corruption on the crosshatch screen?

It was 3.3 but I had the same issues with the stock bios.. seems it was the overclock that this specific board didn't handle well.

On my MV-1C I have the 4.0 Unibios with a similar overclock and no issues.
 

Razoola

Divine Hand of the UniBIOS,
Staff member
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Thats good to know because overclocking has been tested with the crosshatch and its the first time I have seen corruption due to it. Have you had over boards with the same issue on the crosshatch?
 

RyuX

Crossed Swords Squire
Joined
Sep 19, 2018
Posts
179
Thats good to know because overclocking has been tested with the crosshatch and its the first time I have seen corruption due to it. Have you had over boards with the same issue on the crosshatch?

I think this is pretty much exclusive to this board. It had quite some repairs until I got it running, I could imagine a lower resistance to ground than my other boards making it more vulnerable to glitches or errors on higher clock speeds
 
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