Can anyone improve the rgb output on my duo?

[incrediblehark]

I just recently got a turbo duo, and had it region and rgb modded. everything works great, but for the rgb I'm getting the noticeable jailbars and some faint interference on the screen. I know there are some rgb amps that have been made that will essentially eliminate any of this for a near perfect picture. If anyone can provide this service or can build the amp please let me know!

[ogre]

Unfortunately as of yet I have not found anyway of eliminating the jailbars/lines. I have been researching many forums and no one has been able to solve this. I tried 3 different mods and they all produce these lines to varying degrees. All of these mods use the composite video to sync which if you look closely produces these lines as well. Maybe cleaning up composite or finding a way to use c-sync off the chip would help. The only suggestion I can make is to check all the grounds for the mod and the cable. If the ground is not solid it will intensify this issue and add interference.

[Samurai Ghost]

Sorry if this is slightly off topic, but are you saying that all RGB mods for DUO systems produce lines and interference? Can you post an example of what this looks like? Because I'm considering doing a mod to improve the video output of my DUO but might give up the RGB mod if it's inherently flawed...

[BlueBMW]

I dont recall having jailbar issues on the RGB modded systems I've used....  Most of them used composite for sync also.  They were typically based on the NJM2267 amp I believe.

Someday I'll get around to having these amps built...

only 1 1/2" square:

[ogre]

All of the mods I have tried have this problem. The one that has it the least is the one that uses the NJM chip for the amp. I have to see if I can find a picture that shows this better. Most games this is barely noticeable except when a solid light color is present in the backround. Games that have this the worst are all of Shinobi, all areas in China Warrior, alt level 2 in Dracula X, konami logo, some of the cutscenes in Y's, and some of the cutscenes in Double Dragon 2. The composite video has this issue too if you turn up the brightness you can kind of see it.

[thesteve]

my sega rgb mod has no jail bars, using a sony CXA encoder as the amp

im running sync on green not composite as sync

[DynamiteSJ]

I have one of these amps:
http://www.ultimarc.com/vidamp.html

Would that work out good for  TG16 rgb mod as an amp?

[thesteve]

thats an odd amp, as i havent heard of a display wanting over 1V of Vid
that amp converts vga to cab display

[DynamiteSJ]

its an arcade monitor amp.. bought it for my mame arcade machine but never used it since i ditched my arcade monitor and went for a LCD. Arcade monitor is just RGB seperately and sync. Seems like itd work right?

[thesteve]

yes it should work, it just may need 3 resistors added

[incrediblehark]

I'll try to post up some pics soon, I have two rgb pce/turbo systems, a us turbo duo with the jailbars, and a pc engine hooked up to an ifu30 thats been rgb modded. this one is a lot less noticeable, i think its there but the picture is a lot brighter so I don't see the interference or jailbars, which im fine wth. but i want to use the duo.

[grahf]

Hey Blue, would you mind sharing the resistor and capacitor values for that NJM2267 circuit? The original amp design is from here:  http://baku.homeunix.net/RGB/PCE_DuoRX/PCE_DuoRX.html  but it's not so clear to me exactly what values he's using. Plus he's using a transister based pre-amp/buffer, which some folks are leaving out. I already built one of the simplified versions of these amps, but the output was a bit weak. It sucks because all my equipment is still back in the US, so I can't really test the signals.

Here's the one I built:



I ended up replacing it with a simple transistor based amp for now. I just got one of those new XRGB-minis (the XRGB-3 replacement), which luckily likes the transistor amp just fine, but i'd like to finish the NJM amp eventually.

[grahf]

I'll try to post up some pics soon, I have two rgb pce/turbo systems, a us turbo duo with the jailbars, and a pc engine hooked up to an ifu30 thats been rgb modded. this one is a lot less noticeable, i think its there but the picture is a lot brighter so I don't see the interference or jailbars, which im fine wth. but i want to use the duo.

You probably already looked into this, but the interference issues could be as simple as using a noisy power source. Adding a nice sized cap between power and ground might sort it out, or you might try changing to a different power source.

[incrediblehark]

where exactly do I add the capacitor? I tried adding some from the amp to ground and amp to power but didn't work for me. but maybe i was doing it wrong. the power supply is the official duo ac adapter, whats a suitable replacement? I have a radioshack one but it wont power this thing like it does the ifu.

[thesteve]

you want the amp to use the +5 from the internal regulator.
add a 1uf ceramic and a 480uf from the +5 to ground as close to the amp chip as possible