Question about video problem on 5V AES (NEO-AES with daughter board)

[ckchan]

Hi all,

I encountered a video problem on the AES console, part of the screen is distorted.



Remarks:
1) Use original PSU 5V3A
2) Use composite output
3) The console works fine during gameplay (no such distortion)
3) The game works fine with another 5V AES on the same TV
4) The cart slot is cleaned
5) No broken trace can be found on the console board
6) Continuity between the cart slot and the chips is fine

Any idea on how to fix this issue?

 

[maki]

looks like a sync problem to me

does one have the Video PLL daughterboard?
what chipsets are in the AES that works and the one that doesn't?
do they use the same crystal? (24.0 vs 24.16..Mhz)

Neo Geos cause issues with lots of LCDs due to their hor. frequency being out of spec (59.18Hz), IME especially the first gen ICs have the worst sync.
I heard that very early NEO-AES have been equiped with a 24.0Mhz crystal like MVS, later they've used a faster (24.16.. MHz) crystal to improve the Sync.

Lastly, if you have a NEO-AES with a PLL video daughterboard, get rid of it, it messes with the RGB timings to improve the Composite Video timings, bad trade IMO, could be a cause.
Its simple to do, just re-solder the crystal from the daugtherboard to the main PCB in the empty spot, remove all wires to the daugther PCB, then the daugther PCB itself, done.

 

[awbacon]

def looks like you are using LCD. Probably just not syncing perfectly as mentioned above.

Most modern LCD panels do not like / expect signals outside of norms. So it'll take a 59.97 or straight 60 but outside of the 23.97/24/29.97/30/59.97/60 if will have issues

 

[Neo Alec]

The solution to this problem is always to use a digital upscaler or don't use a modern TV. There is a lot of variation in the sync rate between consoles, so you must have just gotten lucky that the other one works okay.

 

[ckchan]

looks like a sync problem to me

does one have the Video PLL daughterboard?
what chipsets are in the AES that works and the one that doesn't?
do they use the same crystal? (24.0 vs 24.16..Mhz)

Neo Geos cause issues with lots of LCDs due to their hor. frequency being out of spec (59.18Hz), IME especially the first gen ICs have the worst sync.
I heard that very early NEO-AES have been equiped with a 24.0Mhz crystal like MVS, later they've used a faster (24.16.. MHz) crystal to improve the Sync.

Lastly, if you have a NEO-AES with a PLL video daughterboard, get rid of it, it messes with the RGB timings to improve the Composite Video timings, bad trade IMO, could be a cause.
Its simple to do, just re-solder the crystal from the daugtherboard to the main PCB in the empty spot, remove all wires to the daugther PCB, then the daugther PCB itself, done.

does one have the Video PLL daughterboard? Yes


what chipsets are in the AES that works and the one that doesn't? It seems to me that all chipsets are in working condition

do they use the same crystal? (24.0 vs 24.16..Mhz) Seems they are not the same.

 

[ckchan]

The solution to this problem is always to use a digital upscaler or don't use a modern TV. There is a lot of variation in the sync rate between consoles, so you must have just gotten lucky that the other one works okay.

I used the Micomsoft Framemeister XRGB-Mini to change the signal from composite to HDMI. The top has a long white bar and the previous distortion is minimized (still have a bit on the top left-hand side of Benimaru scene, sorry for the poor quality of screen capture)

 

[maki]

do they use the same crystal? (24.0 vs 24.16..Mhz) Seems they are not the same.

the main crystal is on the video PLL board, looking at the numbers that aren;t covered by solder, its a 24.167829MHz, thats okay

the purpose of this video PLL daughterboard is to improve the composite signal at the expense of the RGB timings, its implementation is very hacky, a 24.16Mhz signal routed through a shitty wire over and across the mainboard

if you intend to use RGB (you should, no benefits from composite on the NG, just a worse pic), get rid of the PLL daughterboard, just move the crystal to the mainboards empty spot to where one of the wires goes and you're done, you could swap the resistors on the output to 75Ohms to further improve the pic etc.

the white bar on composite could be due to dry caps in the video path

however, Neo Alec is right you know, if you care about the picture and latency, for LCDs you'd want an converter like the OSSC (if you're in Europe where RGB over SCASRT is very common) or a retrotink

 

[Neo Alec]

however, Neo Alec is right you know, if you care about the picture and latency, for LCDs you'd want an converter like the OSSC (if you're in Europe where RGB over SCASRT is very common) or a retrotink

He said he's using the Framemeister, so he's good there. I agree though. Remove the daughterboard and use RGB.

 

[ckchan]

Thanks Maki and Neo Alec. I just tested the console on another TV and it worked flawness.

 

[thegreathopper]

Well done Wilson, a friend of mine has this same issue when he plays his Neo console on a B&O Mx4000, any other old TV it’s fine.