If you got an NTSC Dreamcast console and you live in a PAL country you may have some odd problems with PAL games. The image may disappear off the top/bottom of the screen, or have a weird flicker with a handful of PAL games or Passport Discs.
It is very easy to fix, and combined with a 4 wire modchip or RegionFree BIOS you’ll end up with the most compatible universal Dreamcast. Taking the DC apart is easy, the only tip I can give you is to remember which kind of screw when where. Some people mix up the short/long silver coloured screws – the GD ROM drive is held on with 3 short screws, if you put a long one through here then you’ll damage the motherboard. So be careful!
Once you’ve removed the power board and it’s plastic shield, the GD ROM drive, the controller ports and the final metal shielding you’ll finally reach the upper side of the motherboard which you’ll need to remove so that you can work on the under side of the board.
You need to look for a pair of points labelled R422, they are near the AV Out port. Once located, simply link them up, I’ve used a short length of Kynar wire.
The last one I did, I stripped a piece of wire, held it across the points then soldered it into place and trimmed it to size using side cutter.
That really is it, re-assemble your console and try it out.
I first read about this trick on the forums at DC Emulation. It’s worth visiting the forums (in particular the hardware FAQ) if you’ve got any problem with your DC.