Had great success whitening my PC Engine, CD-ROM
2 and IFU-30. I went with Arkhan's method of using just hydrogen peroxide and light instead of the various Retr0bright recipes. And I used artificial light instead of natural sunlight because I wanted a more controlled environment. First I made trips to my neighborhood pet supply, beauty supply and dollar stores and came home with a canopy light fixture (normally used atop reptile terrariums), UVB bulbs, many bottles of hydrogen peroxide, and various plastic food and storage containers. Here's a rundown.
MATERIALS:[ul][li]
Exo Terra Compact Top Terrarium Canopy, 17.7 x 3.5 x 7.8-inch, Max 26W spiral, Max 25W tube, PT-2226[/li][li]2x
Exo Terra Repti Glo Tropical Terrarium Lamp, 5.0 UVB Compact, 26W, PT-2187 (Power should be in the 300-350nm wavelength)[/li][li]
Salon Care 40 Volume Clear Developer 32 oz. (Hydrogen Peroxide)[/li][li]Plastic food or storage containers[/li][li]Rubber or latex gloves (hydrogen peroxide burns skin so these are a must)[/li][/ul]
Mmm, minty boxes
BEFOREThe RAU-30, which is in its original super-bright white condition, is used as a point of comparison. I recorded the Serial Numbers and removed the stickers with Goo Gone. Then I disassembled and cleaned the consoles with dish washing liquid and an old electric toothbrush.
SETUPUVB bulbs installed in the light fixture.
All of the plastic pieces float so I weighed them down with small rolls of pennies. The larger pieces had rolls of pennies taped to their undersides, while smaller pieces were taped to rolls of pennies. The pieces were completely submerged. The tape would come loose so I checked on the consoles periodically, dried the pieces, and re-applied tape as needed.
The whitening process in action.
These types of containers are perfect if you need to whiten the edges. NOTE: This photo was taken
after the process. Make sure you don't see a DIN connector or power switch when you
pour in the hydrogen peroxide!
AFTERNeither the PC Engine nor the CD-ROM
2 came out as white as the RAU-30, but they look dramatically better.
BEFORE 
The Super System Card is quite yellowed and was not put through the process allowing you to see the change in color of the consoles quite clearly. The white tray of the IFU-30 was also whitened although it's not as easy to tell in these photos.
AFTER - Much better
