Most of retro computers were manufactured in 80s and 90s. After all these years plastic parts often turns yellow, or even brown. Thats mostly caused by exposing it to UV light like keeping it in sunlit place etc. But even without UV light plastic will degrade over years. Except for changing color it can also become brittle. That said one may wonder… How is it possible that you can still buy old computer and it looks just like new? Well, basically it is possible because someone probably refurbished the computer or it was kept in environment which allowed it to be preserved in excellent condition.
So how old computer is refurbished? There are many ways. For example I start by carefuly taking computer apart to separate electronic, plastic and metal parts. Each of these needs different treatment. Electronics may be simply dusted off with soft brush. You can also use special fluids for cleaning electronic parts and PCBs. Most common one is isopropylic alcohol. But thats not the topic we will discuss. Also metal parts restoraion will not be covered in this text. Lets just say you may need to clean metal elements like board shielding or RF modulator boxes from rust and protect them against it in the future. Today we will focus on deyellowing plastics.