Commodore 128 Complete Restoration

I picked up this Commodore 128 and disk drive on Craigslist for $30. The poor thing is in really rough shape In fact, I think it’s the worst I’ve ever seen. The whole thing is yellowed and you can clearly see its from UV exposure because you can see the original color hiding in the shadow of the keys, but the amount of dirt and grime is just amazing. 

Part of this is due to being in storage for years, according to the seller, and, unfortunately, a key is broken off. I do have the key, so I’ll see what I can do about that. The 1571 disk drive doesn’t look any better. I don’t know if either of these items even work. So, really, I felt like the first thing I should do is test them. I plugged in the power and connected up the disk drive and monitor.

So, half afraid something was going to pop and start smoking, I turned on the disk drive. It did spin up and the power light came on. That’s a good sign. Now, time for the computer. Well, the computer seems to be completely dead. In fact, the power light doesn’t even light up. I wanted to test the power supply so I decided to bring out my good, working Commodore 128 to test it. 

So I think we can assume the power supply is good. Next, I wanted to test the disk drive, so I put in an Ultima 5 disk and rebooted. Interestingly enough, I could hear the drive clicking away; the activity light never flashed at all. Eventually the game sprang to life. So, the disk drive appears to be working, except for the activity light.

By the way, here’s what the two 128s look like next to each other. Well, I decided it was time to get to work disassembling this thing.

The Commodore 128, much like other Commodore machines from the era, is very easy to disassemble: just a few screws and you’re inside the case. The inside is covered in dust and dust bunnies, but not as bad as I would’ve thought. I’ll have to take off this RF shield, which also doubles as a heat-sink for the various integrated circuits. 

There’s also a separate shield for the two video chips. You heard me right, this computer has dual video systems: one for 40 columns and one for 80 columns. So, here’s what the logic board looks like. It’s a little dirty but otherwise in pretty good shape. Next, I took the board out of the computer and the last thing was to remove the keyboard out of the top case piece. This is pretty easy too. I noticed when I removed it that the whole keyboard frame was bent.

Apparently, somebody put something very heavy on top of this thing. I really wanted to diagnose what was wrong with this thing before I went any further on the restoration. Oddly enough, I plugged the LED back in and noticed that it does indeed light up now. So, either it was connected in backwards or maybe just wasn’t making good contact before?

So, the next thing I wanted to do was test the voltage on the board. According to the user manual, I should be able to find ground and +5 Volts on the cassette interface here. So, I touched the leads to these traces, and I got a nice reading of almost exactly 5 Volts, so I think we are good there. The next thing I did was to just re-seat all of the socketed chips. I always advise people to do this when they email me about a dead computer. I usually don’t even pull the chips all of the way out I just work them about half way out and press them back down. It’s surprising how often this can fix issues with old computers.

However, I tested again, and it still didn’t boot. I decided to remove the silicon grease. It looked old anyway so I’ll put some fresh grease on before I’m done. Somebody really went overboard on these video chips. So the next trick is to remove some of the unnecessary chips.

For example, the computer will still boot without the sound chip. Granted, it won’t have any sound, but the chip is not required for booting. Well, that didn’t work. Next I tried taking out these ROM chips. I think that one of these is required but the computer will usually display at least something on the screen without the others. So, I just tried removing them one at a time. Well, that also failed to fix it. I also tried a game cartridge. Sometimes these machines will boot with a cartridge even when they won’t boot to BASIC;

However, it was still dead. So, the next step was to grab my working 128 and take it apart. The idea here is to take each chip one at a time from the bad unit and try putting it in the good unit. This way I could verify which chips were good and which were bad; however, it turned out that all of the chips I could remove were good. So, I have verified all of these chips are good. So at this point, the main suspects are going to be narrowed down to a bad RAM chip, or maybe one of the CPUs is bad, and yes – this machine has two CPUs: a Z80 and a 6502-compatible CPU. Both are required for the computer to boot; however, all of these chips are soldered in.

It also could be any one of these smaller supporting chips. It would be quite a chore to desolder these one by one and test them. I also haven’t ruled out for sure that these capacitors aren’t the problem. Still, at this point, I knew I was going to need some help diagnosing this board. So, in the meantime, I turned my attention to the plastics. 

So, the first thing I did was hose them down. This didn’t remove nearly as much crud as I had hoped but it at least cleaned the inside the air vent grilles really well. I followed that up with some old-fashioned Windex and managed to scrub off about 95% of the remaining dirt and grime. You know, a lot of people give up at this stage but this is really just the beginning for me. I always come back with alcohol and do some serious scrubbing.

This will remove the vast majority of black scuffs, paint, or permanent marker, and while this portion of the cleaning accounts for about 5% of the total cleaning, it’s actually the hardest and longest part. I usually spend about 30 minutes scrubbing every little imperfection I can find until its flawless. I did encounter this really stubborn area on the bottom of the computer so I had to try one more thing: baking soda. I just put some on a wet paper towel and scrub with it.

This stuff works like a mild abrasive and it will clean off just about anything but it does remove a small layer of plastic and it’s kind of messy so you have to clean it off afterwards but you can see the result and it worked really well. So, here are the case pieces after I finished cleaning them.

You can already see a remarkable improvement but they are still yellow so well have to come back to that problem shortly. Next, I turn my attention to the disk drive. I disassemble the drive. It’s also very easy to take apart and there are no hidden snaps or anything special you need to know. Basically, did all of the exact same cleaning procedures on the plastics here. Next, I turn my attention to the biggest eyesore of this computer and that’s the keyboard. Besides being filthy, it’s also the most yellowed component. So, first things first, time to pop off the keys. You have to be delicate removing these because it is possible to break them if you have too much sideways motion or bending, but after you get the first few off, it starts to go faster.

Before I knew it, I had all of the keys off but look how gross it was under these keys!

The first thing I did was use a vacuum cleaner. That actually made about a 50% improvement right away. Then I followed that up with some Windex and a paper towel. I used a piece of wood as a fulcrum point and bent the keyboard frame back to the correct shape and here is the finished product. The keys are an entirely different matter. I rinsed them in the sink, cleaning all five sides of each and every key. This is a laborious process; expect to spend at least 20 minutes doing this. There were three keys that had what appeared to be marker residue on them so I had to follow that up with some alcohol. Fortunately, with some scrubbing, I was able to clear that right up.

OK, next it was time for the retrograding. Most of my viewers have seen me do this before I brush it onto the plastic wrap and then I brush it onto the keys, trying to get every surface, and then I do the same thing with the case pieces, and then I set them out in the sun. Ideally, you want to come back and rotate these pieces every 30 minutes or so. I usually massage the cream around under the plastics as well in order to try to get a more even appearance. So, for those who are still wondering if this is a permanent fix for yellowed plastics, well, I wanted to show you this Apple IIc that I did the retro rite to about a year ago. 

Now, this thing was extremely yellow and it still looks pretty darned good, although admittedly, if you look really close, and you probably can’t even see it on camera cause it is very faint, but there is a very faint hint of yellowing right in this spot right there and it wouldn’t be a big deal to fix but considering how bad this thing looked before and considering a year later it still looks pretty good, I think the process is pretty reliable. I used my old drive cleaning diskette. I don’t have the cleaning solution anymore so I just used some alcohol and I made a little mess. Anyway, I just stuck it in there and tried to load something from disk so that it would spin the motor. Interestingly enough, when I re-assembled the disk drive, both LEDs were working.

When re-installing the keys, I always start with the big keys first since they’re a little tougher to put on and it’s easier when the other keys aren’t in the way. It’s always fun watching the keyboard take shape as I randomly re-assemble all of the keys. And of course, we can’t forget the most important key – the Commodore key!

I wanted to fix these broken keys and I kept looking at this trying to figure out what  was in there. After a while I determined this must have been chewing gum. Somebody apparently thought that was an appropriate way to keep the key on. Well, with it being broken like that, the key certainly won’t stay on by itself, so I just added a few dabs of super glue and that seemed to fix that up.

Unfortunately, I discovered these rubber feet had become very sticky. They were sticking to everything I sat the computer on. This is usually a result of heat exposure. Fortunately, I found these replacement feet at the hardware store and while the color is different, they actually fit perfectly. Now it has four brand new rubber feet. Remember that comparison I made earlier where I showed the two 128s?

Well, look at em now. They’re virtually identical. Now that the restoration is done, it was time to turn my attention back to the repair issue. Alright, so, I’m on my way to get some help. You know, no matter who you are in this world; no matter how smart you are, there’s always somebody smarter than you, which in my case is good because sometimes I need some help. So, you know, I’m kind of like the guy on War-games. You know, we share the same name: his name is David and my names David and he has somebody smarter than him that he has to go see to help him out and you know, heck, you might even compare it to Star Wars, you know, so, I’m like…

I might be like Obi-Wan Kenobi, you know; I’m pretty good when it comes to these old computers but, you know, Yoda is always better, so I’m going to see Yoda, although his name is actually Raymond and hopefully, he can help me out with my problem. Raymond must really be a Jedi Master, because it actually gave him a display, even though it was garbled. He got to work using some of his magic tools. The data bus is not coming up properly. Data bus line D3 is just all garbled, so we’re going to take out the CPU and check that out. Having the right tools makes the job much easier.

You just put it on, let it melt the solder, push the button, wiggle the tip back and forth, to make sure you pull all of the solder out from around the pin. Alright, if you do this right, the chip should just lift right out. Now, we’re going to socket this one but, in doing the sockets, there’s a difference: there’s a single-wipe and a double-wipe socket that you could use and what you want to use is the double-wipe. The difference is, is that the single wipe…you can see there’s no contact here on the outside edge. It’s only contacting the inner edge of the chip pin, whereas on the double-wipe, it’s contacting it on both sides. So, use double-wipes – they’re not much more expensive than single wipes. Lot better contact; lot better life. We still have a problem on data bus line D3. Something is screwing around with the bus so we’re gonna have to troubleshoot a little further to find out where everything’s connected and figure out which chip is causing the problem on this.

Alright, so, we have connectivity on all the data lines up here and down through here and here on this board… on this side of the board, and then down here we have continuity but we don’t have continuity between this side of the board and this and we’ve narrowed it down to… there’s a little bit of corrosion down here under this socket so I’m gonna remove this socket off the board; you’ll get a better picture of it.  After he removed the socket, you could clearly see the corrosion. He cleaned it off with some Goo Gone and now you can see the three traces that are affected.

Interestingly enough, two of these were still making contact but he decided to patch all three because it’s only a matter of time before contact is lost on the other two.…and what I’m going to use is… on the back side of the board, I’m going to use some 30 gauge Kynar wire-wrap wire to run the patches. So, I’m gonna install a new socket here and then I’m gonna flip it over and run all of the trace jumpers.  So, here are the finished jumper wires on the back of the board.  So, when you take these chips out and you desolder them, the legs end up all bent up so if you have a pair of duck-billed pliers – some small ones – you can get them in there, and make them nice and straight again to go in the sockets. Alright, now for the smoke test.

There we go!

So, before re-assembling, I added fresh heat sink compound to the RF shields. Although the Commodore machines can run without any heat sink, it will improve the longevity of the chips if you keep them cool and considering these chips are getting more scarce by the day, it would be good to protect them. After putting the shield on, I just double-checked that all of the chips were making contact with the shield. So, this computer is now essentially fully operational, with the exception of the TAB key, which I was not able to get working, even though it does at least cosmetically look nice and it’s really not a big deal because the TAB key is almost never used on the Commodore 128.

It’s kind of like the Scroll Lock key on your modern PC: it’s just really not a necessary key, so I’m just not going to worry about fixing it. So, there were a lot of neat things that I wanted to show you about the Commodore 128 and this disk drive, as a matter of fact, but the videos already starting to get kind of long so I just decided I’d save that for a future episode. I also wanted to bring your attention to the fact that I do have the CD soundtrack now available. This contains most of the music that you’ve heard either on the background of this channel, or the music that I’ve composed on my other channel, 8-Bit Keys and you can buy this on my website. I’ll put a link down in the description. This is not a burned copy, by the way: this is the real thing.

This has actually been pressed and I’m also paying royalties to the musicians that have submitted these songs to me, 

I’ve got another restoration video that’s gonna be coming out on a Macintosh in just a few days

that I think you’re going to like just as much as this one.