I was also disappointed to find that NES carts such as the PowerPak don't work (crashes on boot). It was suggested by RetroUSB to try a higher current capable 5VDC power supply than the included one, but that didn't resolve the issue.
To extract the Retron HD's color palette I had to use a "real" NES cart with Loopy's paltest.nes program. Thankfully John Riggs came through and made me one to use for this project! Surprisingly the captured palette swatches are actually really clean (no noise). I captured the test pattern via the HDMI output from the console to both a Datapath VisionRGB E1, and a BMD Intensity Pro 4K so that I could cross check the results and found no discrepancies.
Without further ado, here's the RetronHD palette. Download RetronHD.pal.
Here are sample images using the RetronHD palette.
|Bionic Commando looks especially egregious with the RetronHD palette! 😜|