Fix Glitchy Famicom Disk System Sprites!

You might remember my glitchy Mario from a previous blog post. Basically I thought my copy of Mario 2 was just old and glitchy, but it appears that it’s actually the Famicom Disk System RAM Cart that was causing the issue!

I googled it and found this particularly useful blog post by synt4x and I’m here to confirm that this works super well! It’s worth noting that the particular FDS Board I have is a HVC-FMR-03.

As syt4x explains in their blog, the PRG lines of the FDS RAM Cart seem like they receive some interference, so by adding in a 9pin 4K7 Resistor Array to these pins, we help ensure there’s no signal interference.

I ordered my 4K7 Resistor Array from a seller on Aliexpress, it took close to two months to arrive so probably try find some a bit closer to home if you’d like this fixed quickly!

The actual soldering job is quite easy:

1. Bend the first pin on the Resistor Array (RA) up.
2. Line up the remaining pins:
   1. RA Pin 2 to FDS Pin 6
   2. RA Pin 3 to FDS Pin 7
   3. RA Pin 4 to FDS Pin 8
   4. RA Pin 5 to FDS Pin 9
   5. RA Pin 6 to FDS Pin 10
   6. RA Pin 7 to FDS Pin 11
   7. RA Pin 8 to FDS Pin 12
   8. RA Pin 9 to FDS Pin 13
3. Put a bit of tape on top to hold it in place while soldering.
4. Solder the above pins to each other.
5. Solder some wire to RA Pin 1 (I used 30 AWG wire)
6. Solder other end of wire to the above spot on the FDS Board

Here’s another couple of pictures to get a better idea:

Here are the results!