I've made an RGB scheme made simple as possible, need feedback.

Hello,
I've been reading a lot lately about the different views regarding the best way to get RGB out of the back expansion port of the PC Engine/TG16/Core Grafx consoles. There seems to be a lot of confusion but most people seem to agree that the official "leaked" spec (the one to the left of the attached photo) is the way to go.

My plan is to build a prototype board that will use a 9-PIN MINI DIN for multi out: Composite (AV) and RGB (Scart). I found a connector that fits nicely in the back port (23x3 female) and would like to try making a mod-less RGB/AV board for the less-electronically-inclined, who are willing to use their console without the CD attachment.

However, my understanding of electronics is pretty limited, and I do need some help clarifying things:
1. Is the "visual" board I've designed 100% reflective of the scheme? Would you change anything?
2. Are there some components I can remove safely? (for example, the resistors that connect the transistors to GND).
3. If I use a normal RGB SCART cable like the ones they sell of eBay for Genesis 2, will the fact that they already have some components inside of them affect the outcome? Should I remove those from the circuit/cable?

Any other input will be great,
Thanks in advance to all of you.

Cheers,
Ben.

EDIT:
The LED is only for power indication, and the EXT slot is mirrored to the diagram because they connect to each other.

 

Somebody is actually making something like this? I will definitely buy one when I get a TG-16 or a PC-E!

About the Genesis 2 cables...



They have 75ohm resistors and 220uf capacitors on the RGB lines. If you add C-Sync (please do as Composite video is a terrible sync source), then cables like mine, which have a sync booster in them, may cause problems. If your board has the space, an 8 pin DIN for Neo Geo AES RGBS cables may work better as those cables lack any components.

I would also like to make a request for this board. Can you add a passthrough for the CD Drive? That way it could sit between the CD Drive and the console, giving you the best of both worlds without mods.

 

not sure i would agree that most people think the old transistor circuit is the best. I would recommend you build an amp with a THS7314 or something similar instead. This circuit works very well:
http://nfggames.com/forum2/index.php?topic=4822.msg33557#msg33557

also, someone is making something similar to what you are talking about.
http://www.db-elec.com/home/News/dbgrafxboosterrevbreadyforproduction

 

The old transistor circuit was fine maybe 20 years ago, there are better stuff today. THS7314 is currently the best for RGB mod.

It won't be easy since there isn't much room without making the console stick far out. On TG-16 and CD base, the bottom lock won't line up anymore and you can't turn it on unless the lock on the bottom is engaged. You can bypass it by removing a plastic piece inside or jumpering the wires to the switch to make it always on. I don't know if PCE and CD system has any locking design but if they do, they would need to be altered to make it work with passthrough RGB connector.

It would be just easier to add RGB mod inside the CD system or have RGB ports installed on the console separate from the rear connector.

 

I see, I will use the amp chip, thanks.

I decided to use the diagram that was posted here, did anybody try it? does it work perfectly?

 

Using an amp is cleaner. Performance wise you won't see a difference. There isn't enough room between the console and the IFU to do a pass through. I've tried. Mod the IFU.

Other things you might consider are an RGB to Component converter if you have any non-rgb CRTs and an EEPROM if you have a programmer.

 

EEPROM? Can that be used in video mod or am I overlooking something?