Neo Geo AES Garbled Screen

GNewman

Pupil of Bonus-Kun
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Hi

I'm hoping someone may be able to offer some advise on a Neo Geo console I'm looking at. I've swapped out the ROM for a diagnostic ROM, but the screen remains substantially the same with the coloured blocks. It also flashes. I'm not very familiar with the Neo Geo, but I've seen similar behaviour on other machines caused by faulty RAM. Before swapping out RAM chips, though, I thought it may be a good idea to check with others as I'm concerned it may be caused by one of the custom chips.

Any help, tips etc. would be appreciated.

Thank you
Graham
 

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lachlan

VB longneck at 8am in the fuckin mornin'
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I would seriously consider confirming each of the traces feeding from the bios. When I socketed my aes (lol) I somehow managed to break a few.
 

GNewman

Pupil of Bonus-Kun
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Thanks - I've already checked that there are no damaged tracks. I should add that the same problem existed before the ROM was socketed and indeed this was the reason I added the socket in the first place (so I could use the diagnostic ROM)
 

BIG BEAR

SHOCKbox Developer,
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You look like you're missing something in regards to continuity because that looks like a problem relative to the bios..The diagnotic bios is useless if the system can't do a self check.
BB
 

GNewman

Pupil of Bonus-Kun
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Okay - I guess there's no harm in checking all the connections again, but I did look before removing the original BIOS and again after fitting the socket so I will be surprised if i missed something twice.
 

BIG BEAR

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Is it just flashing or is it making a clicking sound as well??
BB
 

GNewman

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Well - I seem to be getting a bit further. I checked the ROM again, but no problems found. I decided to replace the two RAM chips near the ROM and CPU, and I now get a red screen. I believe this is a RAM error, but I'm not sure if it is with the chips I replaced or with the other two SMD RAM chips.
 

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GNewman

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This is what I now get with a cartridge in the console.
 

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GNewman

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And a further update - Checking the RAM connections I found a broken trace between the RAM and CPU. A wire link later - then all is working.

Thanks to everyone who helped.

Graham
 

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BIG BEAR

SHOCKbox Developer,
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That is the WORK RAM (red screen generated)near the BIOS and 68k( all three link). The video ram(yellow screen generated) is near the LSPC. chip.
BB
 

Hawwa

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And a further update - Checking the RAM connections I found a broken trace between the RAM and CPU. A wire link later - then all is working.

Thanks to everyone who helped.

Graham
Happy to see that fixed. Thanks for posting the solution.
 
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