PC Engine Duo RX RGB Mod

Duo RX

Installing an RGB amplifer in a PC Engine Duo RX. Changing the AV port and testing once completed. Commission work.

PC Engine Duo RX

I was contacted through my site and asked if I could give a PC Engine Duo RX the RGB modification treatment. The owner already had an existing RGB cable for another PCE of his, so all that was required was to change the AV port to the 8-pin variation, install the amp, and wire it all up.

The Duo RX is a much nicer console than the original Duo. It functions almost identically, but looks more modern and also is a much improved design over the original. NEC went back to using through hole radial capacitors in place of the SND ones. They almost never leak like the SND caps. SO it was a pleasuer to work on a Duo that didn’t need any cleaning or repair work first.

AV Port

After checking the console was in good working order before starting, I opened it up, removed the CD Drive and removed the motherboard from the case. Almost all the work in the Duo RX will be done on the top of the board, with the exception of removing and replacing the 5-pin AV port.

This is replaced with an 8-pin version to carry the extra Red, Green and Blue channels needed.

The new port has a couple of pins in slightly different places than the original. These are for shield grounding. I filed a coupe of gaps in from the board edge and looped then over. It was too close to the edge to drill like I do for the original Duo. New port soldered into place after cutting the RGB pins to stop them from causing problems with the board.

AMP installation

I placed the amp board in an empty area near the AV port. The RGB signal is tapped from the Hu6260 chip as normal.

Green = pin 47, Blue = pin 49, Red = pin 51. C-Sync can also be extracted from pin 44 and is mostly better for RGB picture quality than the composite sync located at the AV port.

5V and ground for the amp board can be tapped from many different places on the board. I used a decoupling cap located nearby.


OK, so that’s about all we need to do here, lets put it back together and test some games in all their RGB goodness.

Firstly let me point out that my camera HATES photographing my CRT TV. The image looks perfect to the eye, but the camera creates noise from the arrangement of horizontal scan-lines and lines of the pixels.
the RGB picture looks clean, and much more solid than the original composite output.

Console reassembled and returned. Done.


“Received my modded PC Engine Duo Rx within 8 days of sending it to Neil.
I’m really happy with the mod. The picture is fantastic, much improved over the standard composite av signal. A very nice job and reasonable price. Highly recommended to any PC Engine owner who hasn’t taken the RGB plunge yet!
I’ll certainly be back for more console mods in the near future.

If you have any PC Engine Duo consoles in need of recapping or RGB mods, please get in contact here

8bitplus 2017

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