Video problems - please help!

[bacteria]

Ok, wired up 4 x 7805's onto a large heatsink for the 5v from a 12v supply. Tested the voltages when the NeoGeo board is on and voltages are fine.

Using diagram:

Wired ground to pin 1 and 28; 5v to pin 3, 12v to pin 6, audio to 10 and L, red (RGB) to 12, green (RGB) to N, blue (RGB) to 13 and C-sync to P.

The NeoGeo MVS board (think it's MV-1C) boots fine, audio plays, but the image is really bad, just black screen with white bits showing some of the game images.

Normally on a game system if the Sync isn't working, i'll use composite line to be C-Sync but there isn't one on the JAMMA as above, only "Sync" on the "P" pin.

What do I do please to get a clear image? If it makes any difference, i'm UK, so PAL.

One thing i'm thinking is i'm testing on an old CRT television which doesn't like NTSC images, although frankly NTSC works fine it just shows B&W not colour. If the image I got was clear in greyscales but not B&W i'd say it's that reason, however being black and white images instead, and bad at that, tends to suggest that sync (P pin) isn't good enough or there's something else at play here.

What do you guys suggest, something simple I hope?

I notice that the Supergun has Scart output and also composite too, so guess there must be a solution to this - all I want is a good crisp RGB image on my PAL television!

 

[Xian Xi]

If you are using RGB there is no PAL or NTSC involved. Use the RGB scart cable.

 

[bacteria]

I'm incorporating a NeoGeo into a unique and comprehensive multi console system, one controller, 17 consoles, one power supply, one SCART output. Unique system. Stacks of different voltages as different consoles need different voltages. Project "Unity" is it's name! Mentioning this to show i'm not a novice to modding! I want to have NeoGeo in this rig.

(details on my forum)

I've managed to get RGB working on other systems fine, using RGB and C-Sync, and i'm taking the pins off the JAMMA connection on the MVS board directly into my system. The video lines are wired to SCART and RGB mode on SCART is enabled.

I've read that using resistors, 100ohm per RGB line can change the image from being black screen and white snowy outlines (like i'm getting), to being a better image, however wondering if that is all that's needed, and if taking the RGB and also Sync off the MVS JAMMA pins directly is fine. RGB via my setup on other consoles (eg Saturn, PS2, etc) work fine.

 

[Xian Xi]

You might need to run the sync line through an LM1881 to clean it up. Out of the many MV1Cs I've modded about 4 of them needed a sync cleaner.

 

[bacteria]

From what I read, the LM1881 is for separating the V and H sync from C sync, although not sure if that's the case.

What I need please is a solution to getting pretty RGB quality working please.

I don't want to have to buy a Supergun unless that is the only easy solution, in which case what's the best for what I need - I am only running the control pins to my own controller so doesn't need to be compatible with any controller like Megadrive or whatever, I just need to tap the usual ""A" button + ground = button press" scenario - but if that's the only way to get what I need then ok. I guess what I need ideally is composite output to tap off for the C-sync to use with RGB; whatever you suggest, i'm wanting to incorporate the NeoGeo into my rig but need a straightforward way to do it. Comments and advice please!

To show the problem, tested 3 systems currently installed into my Unity system:

Tested with PS2:

Tested with Saturn:

Both in RGB mode of course - image as you see is lovely.

Those pics prove RGB works and is lovely on my set. The systems are working as one unit in my Unity rig of course.

Here is the problem - NeoGeo....

Image is black (not the colour in the pic) with white blur around image:

Looks awful.

Proves the image is no different on my old set than a modern television.

I can't see how a few resistors on the RGB lines will solve that issue, but may as well try I guess.

This is most annoying as the audio is lovely, if only the video would work nicely!

I'd appreciate someone pointing me to the solution to this crappy visual on the NeoGeo please!

 

[Xian Xi]

From what I read, the LM1881 is for separating the V and H sync from C sync, although not sure if that's the case.

The LM1881 is a sync cleaner, whoever uses it to separate H and V sync for actual H and V output should be using an EL4583.

It's up to you if you want to use the LM1881 or not, have fun with your project. Check your grounds as well.

 

[bacteria]

I'd read in the forum to use resistors on the R, G, B lines, tried that and as expected, only made the image even darker.

Had a LM1881N chip and wired that up (used 104 ceramic capacitor, that's 0.1uf ceramic, yes?) to this diagram http://www.gamesx.com/misctech/lm1881.htm and didn't make any difference to the black picture with white ghosting as per my photo above.

So, basically back to square one, still no working NeoGeo and wanting your advice please.

BTW, board I have isn't MV-1C it's a MV-1A if that makes any odds.

I really want to resolve this guys, so need your help!


Would buying a Supergun be the answer? They seem to output to SCART so presumably have resolved the issues i've had? (yes/no?) Which one is best, and cheapest if that's the route to go to (unless there is an easier solution?)

 

[hektic]

Wired ground to pin 1 and 28; 5v to pin 3, 12v to pin 6, audio to 10 and L, red (RGB) to 12, green (RGB) to N, blue (RGB) to 13 and C-sync to P.

Are you sure its a sync issue? I've just built my first SG but when I had no sync I wouldn't get a settled picture like that...
Try wiring up 5v to C,3,D and 4 and 12v to F and 6, wire all the ground pins also.

Good luck!

 

[Xian Xi]

Where are you tapping sync from on the MV1A?

Edit: Nevermind, I forgot you said from the jamma edge. You sure RGB mode is activated on your TV for the Neo? I know the other systems are but can you confirm it's in RGB mode when the Neo is on.

 

[bacteria]

Yes, it's in RGB mode in the same way as for the other systems too, which is why I posted pics of two other systems running to show it working normally. SCART is activated to composite or RGB mode by applying between 1v and 3v to pin 16 of SCART; i'm feeding it 1.9v off one of the many regulators in my system.

I've not wired to all the pins indicated hektic as the continuity test shows they are connected anyway (and visually to with pin-through connections) although I will wire all the other connections too as nothing to lose, and if that's the answer, would be awesome. I'm not expecting that to make any difference though.

Yes, wiring directly to the connections on the JAMMA edge on the Neogeo, this isn't running on an arcade machine.

 

[Xian Xi]

Does the RGB off the Neo have a direct path or does it join other cables from other systems? Could be an impedance issue.

 

[bacteria]

The setup to my system is that each console has their positive voltages connected all time, however grounding is segregated between systems to isolate them from each other, as proprietary consoles hate working together otherwise; segregating the ground keeps them all separate in effect, hence why it works. It is a complex project!

Each system runs into two 8PDT switch, one side for audio and video including RGB mode, and the other side for controller connections, to keep them separate from each other too, otherwise signals would get mixed and unexpected results follow. Each system has on/off switch too, and the whole system has an on/off as a master on/off switch.

I had had it so the idea was to press the single button that activated the two 8PDT switches, then press the master on/off onto on, then the separate console to on to get things working, however, i've discovered that gives the result i've had - if instead I press the button to activate the two 8PDT switch for NeoGeo and also the console on/off to on; THEN turn the master on/off on, I get the NeoGeo working perfectly now!

I have also wired all the 5v pins, 12v pins and also groundings together too, not sure if that contributed to the success.

So, YAY, NeoGeo working nicely! Tested on my three carts, Metal Slug X, Neo Turf Masters and Puzzle Bobble - look and sound great!

 

[channelmaniac]

My Sony Bravia HD Monitor would look like that with the AES. Some TVs just don't like the signals from SNK systems.