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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“Aluminum” Really?! I thought you were German, or from somewhere in Europe?
Hi Mark, no I’m Danish 🙂 Do you think the metal wrapping on the cardboards are made from a different material than aluminum/aluminium? I was almost certain that it was made from that material. Please share if you have more information than me 🙂
MtnBuffalo, Apologies for thinking you’re German, I was referring to your use of the word “aluminum” instead of aluminium, I wasn’t disputing the material.
Perhaps petty on my part but literally two minutes before I read this page I heard my 5 year old daughter pronounce tomato like an American (toe-MAY-toe) which drives me mad…
Anyway, Americanisms aside, I appreciate you site!
He he…no offense taken 🙂 Happy to hear that you like my site.
These are great mods. Keep the ventilation holes the same size as the holes in the OEM shields to prevent EMI.
Very interesting… I’ve got quite a few C64’s (UK Pal) earlier & newer models. Never have I had one with a ‘Metal shield’ Cardboard but not metal? (Maybe they had been previously removed). Got to get round to putting those heat sinks on. ?
Hi I took a C64c with a metal shield (rev.3 hong kong) and inside I found 2 plastic inserts to avoid short circuits on the back of the motherboard, from the photos I don’t understand well, even in your there are 2 (one above the other) or one??
thank you
Hi Ago, mine has two transparent plastic sheets under the motherboard as well. None of them goes on top of the motherboard 🙂
@MtnBuffalo Thanks for reply 🙂
Hi, I’m looking for thermal and RF-noise shield for the VIC-II – aka `coolie hat’, the lid on top of a metallic compartment for my ASSY# 250407 Rev.C
Many thanks,
Tom
Hi Ago, nice restoration work. I received my 1st ever C64 Assy#250407 Rev.C. The noise shield is present on modulator, but not on the VIC-II compartment (the ‘coolie hat’). Can use RETROLEUM heat sink. I am curious, if the metallic VIC-II shield could be removed.
Many thanks for not deleting my post by moderator,
Thomas
Hi Tomas, congratulations on your new hardware 🙂 I have a few spare VIC-II ‘collie hats’/cooling boxes if you want one. I usually remove them when I restore a motherboard. It’s much easier if I want to add e.g. a LumaFix64 at a later time. However, instead of the VIC-II metal box I always add a heat sink to the VIC-II (along with the MPU, SID and PLA) to keep the temperature down as much as possible.
Hi MtnBuffalo, many thanks. I have ordered the lid from RETROLEUM along with heatsinks for the CPU,PLA and SID. I needed the sinks anyway and they happened to have a spare lid, too.
@MtnBuffalo I have a short board, keyboard, and PS from 1987 that i (finally) recently purchased a C64C case for from Hungary. It included the case, top and bottom metal tins, the bottom insulator sheet, along with the keyboard brackets and mounting screws. It was a Hong Kong production C64C with 3 case screws, not snap locks. In this case the variation is, instead of the double plastic insulation sheet, it has a die cut dark blue heavy cardboard cardstock-like insulator sheet. Oddly enough it seemed immediately familiar from long ago. As if i remembered this blue sheet from long ago. Not a detail i would recall today! 🙂
I am a radio amateur, and notice big difference in RF interferance on the 2 meter band from the C64C, from the older C64 (breadbox) there is no interferance. I am not sure where or what device/chip makes the noise.
Anybody else notice? or have any experience?
Hi mate! question…where you get those heat sinks???! they are great! love your site!
Hi Sebastian. The heat sinks are the ones that came with my C64s machines. You may be able to source them off the internet. Otherwise, you could use 3rd party heat sinks with thermal tape …