To reduce any radio frequency (RF) interference with surroudning hardware (e.g. old tube TV’s), Commodore added shielding to their machines. In the early machines the RF shield came in the form of an aluminum covered cardboard that was wrapped around the motherboard. As carboard is an excellent insulator, the RF shield basically trapped all heat dissipated from the precious chips (PLA, VIC-II, MPU, SID etc.). Later Commodore made the shields in metal, added venting holes and made cutouts that would work as heat sinks. These worked much better!
I usually remove the shields regardless of what they are made of and then add my own modern day heat sinks (link, link). Below are examples of some of the RF shields that I have removed from machines made of cardboard and metal.
RF Shields made of Cardboard
Examples of cardboard shields made for long boards and short board Commodore 64’s. The shield for the C64C short board has venting holes for the larger chips (SID, VIC-II and MPU).
Commodore 64 RF Shields made of Metal
This RF shield is made of metal and has plenty of venting holes. The motheboard is an Assy 250466 long board installed in a C64 slim case. I’ve kept this shield installed as it looks pretty cool! The shield also work as a heat sink for the BASIC, Kernal, CHAR, SID, MPU and PLA chips.
This RF shield is installed in a C64C slim case with a short board. The bottom part has a plastic insert to avoid shorting the backside of the motherboard. The larger chips (SID, VIC-II and MPU) touch the shield in order to use it as a heat sink. I’ve also kept this RF shield installed as it is in excellent condition.
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