How to open a Commodore 64 or VIC-20

The original breadbin-style Commodore 64 and VIC-20 are designed to be easy to open while keeping production cost reasonably low. But they made the design so easy it’s hard. Worse yet, due to the age of the plastics, if you open one today the way Commodore intended, you can damage it. So here’s how to open a Commodore 64 or VIC-20. Let’s also talk about how to fix one if you damage the case when opening it.

The breadbin-style 64 and VIC-20 have three large L-shaped tabs on the back that originally behaved like pivots or hinges. If you try to use them like a hinge today, you’ll probably hear plastic popping, so the trick is to open the case slightly, then pull the top forward.

The tabs in the back of the case

How to open a Commodore 64
The tabs on the top half of the C-64 and VIC-20 case are fragile. When you go to open a Commodore 64 or VIC-20, resist the temptation to use them like a hinge, to avoid breaking them.

The VIC-20 had tabs on the back to let you open it like the hood of a car. This mimics the style of the earlier Commodore PET, but without the expense of a full hinge. The breadbin-style C-64 inherited this design.

When the machines were new, this design worked well enough. But just like me, the plastics in these machines started losing a lot of their flexibility after three decades.

I know from my own experience that the design worked great when these machines were only a few years old. You removed three screws, flipped it over, flipped the top half of the lid open like the hood of a ’71 Plymouth Duster, disconnected the power and keyboard cables, and went to work.

Try that today, and you break the tabs and then you end up with a case that doesn’t hold completely shut in the back.

How to open a Commodore 64 or VIC-20 without breaking tabs

To open a C-64 or VIC-20 without breaking the tabs, you have to do it a little bit differently now. Flip the machine over and remove the three screws in the front, then flip the machine back. But instead of lifting the top of the case like the hood of a car, tilt it up very slowly and gently, and only about and inch up. Then gently pull the top of the case toward you. You want to pull the top forward just enough that the tabs clear the slots in the back. Then you can lift the top half of the case straight up without damaging anything.

If at any point you hear the sound of plastic snapping or popping, stop. That’s the sound of a tab starting to break, or possibly already breaking. Lower the top of the case a bit more, then pull toward you. Back when the plastic had some give to it, the slot acted like a hinge. But today, it acts like a lever.

If you break a tab, read on to see how to fix that.

How to reassemble a C-64 or VIC-20 without breaking tabs

You can break tabs off during reassembly too. I’ve done it. To reassemble a C-64 or VIC-20 without breaking the tabs, hold the top at a shallow angle, maybe 30 degrees, and line the tabs up with the slots in the lower half. Fortunately you can see if the parts are lining up as you put it together. Once you put the tabs in the slots, you still have some give both to the left and the right. Line up the sides so the right side of the case clears the part with the ports and the power switch, then drop the front down.

How to fix broken tabs on a Commodore 64 or VIC-20

All too frequently, you end up breaking a tab no matter how careful you are. Or you may do the job perfectly, only to find someone else who worked on the machine before you broke off one or more of the tabs.

Some people 3D print replacement tabs. That works well but isn’t your only option. In the case of the VIC-20 I worked on last, I found most of the busted tabs rattling around inside the case. I glued them back on with some 5-minute epoxy. Not knowing which tab came off which post, I couldn’t get a perfect fit, but you don’t need a perfect fit. The slots are a bit oversized.

I used some JB-Kwik but frankly it’s not the best thing to use. The cheapest clear epoxy you can find is a better choice, because you don’t want epoxy that cures as hard as steel. The cheap stuff will retain some flex and give you some much-needed wiggle room the next time you open the case.

Also, if you don’t mix the epoxy super thoroughly, it can take much longer to cure. It eventually will, but if your five-minute epoxy behaves like five-day epoxy, that’s why.

If the tabs are broken off and you can’t find them rattling around, I’ve built up replacements by cutting pieces from plastic zip ties. One piece of zip tie the thickness of the post, plus another piece of zip tie that extends back a millimeter or two toward the back of the case seems to work well for me. Epoxying those tiny pieces of zip tie into place takes some patience but it’s doable.

If you see a tab that’s hanging on but cracked, you can reinforce it with some epoxy. You can even cut a piece of zip tie and glue it behind the crack for some extra reinforcement.

Was this poor design?

Commodore made some questionable decisions, but I don’t fault them on this design. Several of the engineers who designed machines for Commodore in the early 1980s are still alive and give speaking engagements. Bil Herd says he’s surprised people are still interested in the stuff he designed. He’s clearly appreciative. But he’s surprised his old stuff still works and even more surprised that anyone cares.

This looks like a case of planned obsolescence, but these machines were going to be obsolete whether anyone planned it or not. Even in 1980, when Commodore announced the VIC-20, it was clear that 32-bit computing was the future and it was coming on fast. It’s true that 32-bit computing didn’t become mainstream until 1995, 15 years later, but that was a surprise. Commodore’s engineers knew about the Motorola 68000 CPU and other similar CPUs. And in 1983 when I was a curious kid reading every book or magazine about computers I could get my hands on, everyone was saying we were a year away from a computer revolution. Then they kept predicting the same thing year after year, clear through 1994.

The VIC-20’s job was to get as many computers into as many homes as possible as cheaply as possible, then hand the baton to whatever came next. That turned out to be the C-64, and it had the same job.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this:
WordPress Appliance - Powered by TurnKey Linux