Neo Geo AES Pal to NTSC conversion

[Vendest]

Creating a new thread about this specific issue.
I own an AES 3.3 Pal 50hz / stock bios NEO-EP0
This is what I have done so far.
- Replaced crystal 4.43 by 3.57
- Disconnected jumper PAL1 & PAL2
- Bridge up NTSC to pin 7 of CXA1145P
- Pin 7 is supplied with +5vdc confirmed
- Using RGB scart cable

Main issue
- Obvious vertical refresh rate issue
- Confirmed NTSC display on

Temporary fix
- Added jumper PAL1
- Image displayed is crystal clear / perfect color (better than my MVS)
- Ended up with NTSC/50hz

Any suggestion on what I could be missing would appreciated
And yes I have read many thread on this forum about this topic.

Thanks

 

[pulstar]

Do you have an NTSC TV? Just thinking that the crystal you changed would control the colour sub-carrier signal from PAL standard to NTSC? Although this shouldn't matter much if you were using RGB.

When you say refresh rate issue, is it rolling or is something else happening?

 

[Xian Xi]

Make sure you cut the PAL jumper next to the video ram, that's the one that flips it between 50hz and 60hz.

 

[Vendest]

Do you have an NTSC TV? Just thinking that the crystal you changed would control the colour sub-carrier signal from PAL standard to NTSC? Although this shouldn't matter much if you were using RGB.

When you say refresh rate issue, is it rolling or is something else happening?

I may need to use the composite or S-video signal later on so I wanted to replace the crystal.
The screens rolls from left to right or the other way around.
My TV does not have issues with other systems be 50hz or 60hz and the AES is hooked up to the Framemeinster.

 

[Vendest]

Make sure you cut the PAL jumper next to the video ram, that's the one that flips it between 50hz and 60hz.

Ok I have removed the jumper PAL 1 near the video ram and the sync issue is back again.
However this time I have tried it out with a composite video cable and it works just fine.
I cannot understand why would the RGB signal give me this sync issue in 60hz and doesn't in 50hz.

 

[pulstar]

Not sure if it has anything to do with it, but the horizontal sync rate is a little odd on Neo Geos (59.18hz which is okay for CRTs, but not for a lot of LCDs/Plasmas). Maybe the Framemeister isn't liking this refresh rate maybe. Can you connect directly to a TV/Monitor instead of going through the Framemeister?

If not, maybe a sync stripper will help, if you don't already have one in the RGB cable.

 

[Vendest]

Thanks for your inputs.
I won't be able to connect the Neo Geo directly to the TV other than with composite and my RGB cable does not have a sync stripper (something I should look into!)
Does the MVS have the same horizontal sync rate 59.18hz? Since I am using the MVS with same setup, RGB cable to Framemeister with no display issue.

 

[pulstar]

Does the MVS have the same horizontal sync rate 59.18hz? Since I am using the MVS with same setup, RGB cable to Framemeister with no display issue.

Yeah, MVS would have, so that shouldn't be the issue. I suppose you've already tried (if it does), but does the Framemeister have any way to adjust horizontal hold? If not, think about building a sync stripper circuit, not 100% sure it would fix the issue, but worth a go if you can get the bits cheap.

 

[Atro]

Desolder pin 3 on the DIN8 and solder to pin 7.

Your TV set might not like getting sync from composite sync.
On my Thomson CRT I had a similar issue like your, only with my AES.
Since I changed the sync, all worries went away.

 

[Vendest]

Many thanks Pulstar, you nailed it!
I've adjusted the sync level of the framemeister.
Problem solved
I'll still build up a sync stripper anyway. It won't do any bad.

 

[ResO]

Many thanks Pulstar, you nailed it!
I've adjusted the sync level of the framemeister.
Problem solved
I'll still build up a sync stripper anyway. It won't do any bad.

View attachment 37340

That little orange thing with the phillips head adjusts something horizontal. I remember on SVC Chaos through svideo back in the day there were crazy fast horizontally moving red bars. They would go left or right as you adjusted the screw one way or the other. Dial it in just right and they woukd stop scrolling dead in their tracks. Not sure if this is relevant, just thought i'd mention

 

[Vendest]

You must refer to the the orange trim cap located near the CXA1145. I have tried to dial it slowly to the left then right without getting any results. Though I haven't touched the one located at the bottom of the PCB.
Apparently it was not related to the hardware but some adjustment needed on the display itself.

 

[Vendest]

Desolder pin 3 on the DIN8 and solder to pin 7.

Your TV set might not like getting sync from composite sync.
On my Thomson CRT I had a similar issue like your, only with my AES.
Since I changed the sync, all worries went away.

Hi Atro, I did not have to do that but just a thought about moving the wire from pin 3 to pin 7.
Pin 7 by default is blanked, how does the RGB signal behave without any sync signal coming in? I never had tried

 

[Atro]

Hi Atro, I did not have to do that but just a thought about moving the wire from pin 3 to pin 7.
Pin 7 by default is blanked, how does the RGB signal behave without any sync signal coming in? I never had tried

Pardon my previous post.

I meant to say your TV set might not like composite video as a source for sync.

Pin 7 is also sync for the AES.

 

[Vendest]

Solved (AES Pal to NTSC conversion)

I have built a sync stripper LM1881 and installed it in the scart connector as recommended by Pulstar in this thread.
The image is pretty neat now although I'd like to mention how damn picky is the framemeister when it comes to sync.
I had to add a 460ohm resistor on the sync line in order to make it work.
Anyway thanks ya all for your replies.

I can now enjoy an AES converted NTSC 60Hz with crystal clear image

 

[Rot]

I have built a sync stripper LM1881 and installed it in the scart connector as recommended by Pulstar in this thread.
The image is pretty neat now although I'd like to mention how damn picky is the framemeister when it comes to sync.
I had to add a 460ohm resistor on the sync line in order to make it work.
Anyway thanks ya all for your replies.

I can now enjoy an AES converted NTSC 60Hz with crystal clear image

Congrats Vendest...

I hope you stick around and can help other members out now... the tech forum is helpfull... but only if the members help each other out like they helped you...

##rot4techmod2016....

 

[ResO]

That's really awesome that everything worked out. I almost picked up a PAL AES last week and passed up a great deal because I thought it was a terrible uphill battle. This thread is very encouraging!