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Version 4.0 (NESRGB40) boards sold between November and December 2022, marked with 22.38 date code on the silkscreen, or 22.31 date code and V2 marked on the FPGA in silver pen, also have a bug in the firmware. The problem is exclusive to front loader NES consoles. The NESRGB board will start up in off mode every time, and will not remember the palette selected.
This bug is caused by an incorrectly configured PLL reset signal inside the FPGA firmware. Fortunately, there is a simple fix. There is a redundant reset signal generated on the NESRGB board already. This is because the Famicom consoles don't reset the PPU, the reset pin is tied to the 5V supply on these consoles. The fix is to just cut off the RESET pin off the NESRGB board assembly, isolate it, and connect it to +5V, just like it is on a Famicom.
Modification procedure
1. Cut pin 22 (RESET#) off the NESRGB board assembly.
2. Put some electrical tape over pin 22 of the socket on the motherboard.
3. Solder a 1k resistor between pin 40 (+5V) and pin 22 (RESET#) on the NESRGB board. If you don't have a resistor handy, just make a direct connection with some wire. Install the NESRGB board back in place on the motherboard and use a multimeter to measure the continuity between pin 22 on the motherboard and NESRGB board to make sure it's not connected.
Last updated 15/2/2023
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