This modification adds switchless NESRGB and IGR (in-game routines/in-game reset) to a Nintendo AV Famicom.

First look at the opened AV Famicom and the NESRGB kit. A lot of assembling needs to be done.

The desoldered PPU – this is a hard part as some of the pins are soldered on both sides. Even with a solder gun it takes quite some time. Also note the C5 capacitor, which will be in the way of the NESRGB – better replace it with a new one that has longer legs.

The fully assembled NESRGB kit, ready to be plugged into the new socket.

The C5 capacitor is lying right underneath the NESRGB.

Add wires to the palette selection switch and to the AV port.

The first step of the modification is done: The palette will be selected with an external switch.

For the switchless part we’ll need a daughter board: The NESRGB-IGR by borti4938.

There are a couple of hex files for the PIC. The code explains the differences and I went for the var_led variant.

The daughter board can sit right on top of the NESRGB with the help of a pin header.

Some more wires to intercept the reset and controller signals.

Final test:

You can place the LED next to the power switch. When the case is closed, you will see a dim glow through the switch.