NEC SuperGrafx: In For RGB Modding

You don’t see these consoles everyday. This ugly boy is the NEC SuperGrafx. It’s a slightly upgraded PC Engine from Japan. It was supposed to be the replacement for the PC Engine. It featured more memory and a greater colour palette than the original. However, it didn’t have the same market success. There are only a few dedicated SuperGrafx games, but its fully compatible with PC Engine HU Cards. I’m not a fan of the case design though.

This particular example was sent to me by a customer who wanted an proper RGB mod installing. At some point, someone soldered an RGB scart cable directly to the board. However, it’s not amplified and looks rather dark on most TV’s. The cable runs out through the side of the AV port.

Lets see if I can do a better job then this original mod installer shall we?

Installation

RGB modding the SuperGrafx is very much the same as with NEC DUO and other PC Engine consoles. They all use the same 5 pin AV port for composite video, audio (lest and right), 5v and ground pins.

I’m removing the original 5 pin port and replacing it with a new 8pin port. The additional 3 pins will be for the amplified colour signals. The un-amplified colour signals cab be either taken from the rear EXT connector, or directly from the Hu6260 IC. This is my preferred method here as its closer to the location I’ll install the amplifier board.

Testing

Now with the working amplifier board in place and a good RGB cable, the image is sharper and brighter.

Before fully reassembling, I replaced C168 and C169 on the underside of the board with new 4.7uf SMD caps. This is optional mod removed “jainbars” in video output that can sometimes be seen in solid bright colour areas. More details here.

Also the owner brought this to my attention that I didn’t know. One of the plastic standoffs is possible pressure point on this console. Its recommended to cut down the plastic to prevent damage to the motherboard. Details here.

Ready to send back to the owner.

Neil – 8bitplus – 2025