If you have an old device, you will have noticed that over time, white plastic starts to turn yellow, something that does not look nice for your -retro- device. There are many ways to remove the yellowish from the plastics, but most require a kind of chemistry to make or use bleach-type cleaners. See how it can be done much easier and faster in that way.
All you'll need is a cleaner, which contains hydrogen peroxide, the more the better (no less than 30%). You can buy it from stores that sell cosmetics. It is in gel form and spreads very easily, as long as you use protective gloves when you do.
I used the following product, which I bought it very cheaply (about €3).
Of course you can use a similar product, this is not a miraculous stuff, it was just the one I found at the time. I say this so you do not just look for this one only.
The way to use it is simple. Open your device and remove the plastic parts you want to clean. If there are some buttons or a board, remove them.
Put a good amount of product on your fingers (always with gloves) and brush it on the console or the device you want to clean, making sure the material covers well the area. Allow to dry (well on a balcony or outside your room, but not under the sun) and leave it for some time until the material no longer appears on the plastic.
Now you can repeat the process if the yellowish is not completely removed or you can clean the plastic with water and wait for it to dry completely before you mount it.
Its results are surprising. In the image below, see the difference in a NES case, where the front piece left as it was and the time I left it was just two hours.