Friday, January 05, 2018

Amiga 500 Restoration: Retrobrighting I

In part one I described how I got and disassembled an Amiga 500 for a thorough cleaning. This part is about my first attempts to restore the grey/beige color the case had originally had, but over time had turned it an ugly yellow.

First Things First

Disclaimer 1: It has been quite a while since my chemistry lessons in school, and even though reading up on the details, combined with what I still remember, left me with some confidence of having roughly understood what’s going on, what follows might be woefully wrong, at is guaranteed to be imprecise. So by no means should you use this as the basis for any upcoming exams ๐Ÿ˜‰. Also, I understand the links provided are not scientific publications, so they themselves might be wrong. If you know better (and can point me to the resources to prove it), I would be happy to hear from you.

Disclaimer 2: Hydrogen-peroxide and products based on it need to be handled with great care. Always wear rubber gloves and, even more important, protective glasses when handling it. I know this might sound like an exaggeration, but I am serious: H2O2 is acidic! Getting it on your skin will cause discoloration and burns. Here’s a picture of my arm where some of the stuff got stuck without me noticing.

Hydrogen-Peroxide Burns on my skin after just a few minutes of accidental exposue

After what could only have been a very few minutes, I felt a stinging pain and could see two burnt spots. It took  quite a while for the pain to subside even after washing off the peroxide. It goes through your skin and starts to make gas bubbles underneath. So if by accident you get some on your skin, quickly rinse if off with clear water!

Getting this stuff in your eyes can cause irreparable damage and even blindness! You have been warned!

Why does plastic turn yellow?

There are quite a few theories out there why the plastic many older electronic devices — including the Amiga — were made of turn yellow over time. Not all of them do, some keep their color well, while others look quite grotesque. The one I bought from eBay looked like this when I got it (and yes, the photo is rather close to what it looked like in person).

Amiga 500, yellowed plastic, straight from ebay

As far as I could figure it out, external influences like heat and UV light gradually break up molecular bonds in the polymers comprising the plastic, leaving free radicals. The presence of bromide flame retardants, often cited as the main culprit, may or may not play a role in this process, but if my layman’s reading of this paper is correct, plastic can change its color regardless. In any case, the changed molecular structure changes the physical properties in several ways. For one, the material can become more brittle, but also, the wavelengths of the light it reflects shift. It seems, free radicals like yellow best, so that’s what they tend to reflect most ๐Ÿ˜‰ (and yes, that smiley is there on purpose).

Fortunately, these chemicals processes can apparently be at least partially reversed by re-adding hydrogen for the free radicals to bond with. Unfortunately just soaking the plastic in water won’t help, because the hydrogen in water is very happily bonded (with oxygen) already. It’s not as simple as one might expect, but in the end, there are always two hydrogen atoms, and one oxygen atom, sticking together; hence: H2O). What's needed is “bachelor” hydrogen, ready to enter a bond with the yellow-loving free radicals.

A rather cheap transport vessel for extra hydrogen is hydrogen-peroxide (H2O2). While it looks similar to regular water, it is less stable and — if pure — usually decomposes into regular water over time. Given the chance, however, the additional hydrogen may also decide to connect with the free radicals in the plastic, bringing it closer to its original structure, and thereby color.

So put in very simple terms, getting plastic de-yellowed should work by just soaking it in hydrogen-peroxide, ideally adding some energy to encourage the chemical to split off the extra hydrogen to facilitate the reaction. 

A Bucket full of H2O2?

Turns out, an Amiga’s case is surprisingly big, meaning that if I wanted to submerge it in hydrogen-peroxide, I would need a large enough container to put the top and bottom cases in, and also quit a bit of hydrogen-peroxide. This would be the ideal solution, because it would ensure the whole surface being in contact with the chemical, hopefully leading to a very even discoloration.

It certainly can be done (see this video on YouTube), but for my first attempts it didn’t seem very practical. Not only did I  not have a suitable container at hand, but (in contrast to The 8-Bit Guy whose video it is) I also don’t live in Texas with an abundance of sunlight. Instead, live in somewhat cloudy Germany. Trying this shortly before Christmas also wasn’t exactly the ideal time of the year in terms of daylight hours.

So I postponed the liquid hydrogen-peroxide plan for a little while.

First tests: Bleaching the power supply with a standard hair bleaching product

I decided to perform the first bleaching experiments on a test object that is typically not the focus of a lot of attention: The power brick. I figured that if something went wrong and the results weren’t good, it would be the part I would least be annoyed by if it didn’t look perfect. It’s usually hidden under the table anyway.

So first of all, I took it apart (turns out, it was quite dirty on the inside, so it was also a welcome chance to clean it) to get the plastic parts ready.

Amiga Power Brick Top and Bottom Case, disassembled, yellow, on plastic wrap foil before bleaching

The underside was considerably less yellow than the top, supporting the theory that exposure to light (or lack thereof) plays an important role in the chemical reactions described above.

I bought the strongest hair bleaching product I could find in a local store. Even though the brick would have fit in a large pot and could have been submerged, I decided to try out this equivalent of the “Salon Creme” used in the 8-Bit Guy video.

I don’t have the packaging anymore, but as far as I remember it did not specify the exact concentration of hydrogen-peroxide anyway. I figured that even the strongest one would probably not exceed the product shown in the video. I was a little concerned, because the list of ingredients contained some additional stuff, including ammonia, perfume and others, but that’s exactly why I picked the power supply as a “guinea pig”. One box of this product sells for around 3€ or 4€ , so it wasn’t a big investment either.

Schwarzkopf commercial hair bleaching product. Amiga Power Brick case part, yellowed, laying next to it.

I mixed the ingredients as per the instructions, producing a white creme that didn’t even smell too bad. I then laid out the case parts on plastic wrap and started applying the creme generously. Once done, I wrapped the plastic film around to prevent the mixture from drying out.

Hair bleaching creme, being applied on the power brick case with a brush. Gloved hands.

Hair bleaching creme, being applied on the power brick case with a brush. Close up.

Power brick case, with hair bleaching creme applied, being wrapped up in plastic. Close up.

Top and bottom power brick case parts, with bleaching creme, fully wrapped.

For the very first attempt, I just let it sit over night, without any light or heat added. I wanted to find out, how much of a reaction I would get without any additional energy. After about 12 hours I unwrapped and rinsed both parts to see… nothing. At least there was no obviously discernible difference between before and after. I won’t rule out that letting this sit for much longer would have produced some change, but I was not patient enough to try. So instead, I repeated the whole thing the next day — with a fresh batch of the white creme.

This time, once both parts were covered and wrapped, I put them into the oven, heated to around 50°C. I deemed this a safe temperature, because I figured a power supply could reach it by itself on a summer day. Apparently my oven is not designed to maintain such a low temperature constantly. I had put in a thermometer next to the plastic parts. Turns out, the actual temperature and the one displayed by the oven itself were quite different. It only reached 50°C on average when the knob was dialed to around 65°C, oscillating by about 10°C in either direction.

Power brick case parts, bleaching creme applied, wrapped in plastic. In the oven, thermometer showing circa 55°C. Trapdoor cover.

The part in the middle is the trapdoor cover for the memory expansion port. It was put in for comparison. It showed almost no yellowing in the first place, and I wanted to see what effect the bleaching would have on original color plastic.

I left it in there for a few hours, regularly checking the temperature and looking for obvious changes. Very quickly the creme increased in volume, getting foamy — similar to shaving foam. Over time, bigger gas bubbles formed. After about 4 hours the bubbles started to disappear. It looked as if the remainder of the creme was beginning to dry out, turning into a something I can only describe as “crisp looking". At that point I decided to take the parts out of the oven.

Even through the plastic film, I could feel that the creme had indeed begun to turn into tiny crystals. I assume, the plastic wrap was not a good enough seal against the constant stream of warm air. So the water in there eventually evaporated. It’s not easy to see in the photos, but I tried highlighting the effect:

Close up of bleaching creme crystals.

I rinsed everything with warm water, using a brush to remove all sticky residue.

Rinsing the power brick top case, using a brush to remove residue.

(Alert readers might have noticed that I am not wearing gloves here. This is because I had forgotten to take a photo earlier and posed again, but only after having thrown the gloves away already).

Even before the parts had completely dried, the effect was already obvious. I had put a small piece of scotch tape on the side of one of the pieces to make the before-and-after comparison easier. 

Power brick after bleaching. Scotch tape on a small patch for reference, still showing the previous more yellow color.

So the bleaching had obviously worked, which can be seen even better in the next photo, with the mouse as a reference. However, the creme drying out had the ugly side effect of getting an uneven, quite blotchy overall appearance. 

Power Brick after bleaching, next to unbleached mouse for color reference.

Lessons learned (so far)

After the two attempts with the hair bleaching creme, I came to the following conclusions:

  • There is obviously enough hydrogen-peroxide in the cheap hair product to counteract the yellowing.
  • Additional energy is needed to achieve an effect in a more reasonable amount of time.
  • UV light is not the only source of said energy — moderate heat works, too.
  • Letting the hair creme dry produces crystalline particles. That causes ugly spots and an overall uneven result. Some of that might also be attributed to uneven application of the creme.
  • The trap door cover hardly changed at all, so the effect on “original” color plastic appears negligible.

In general I'd call this first try a partial success, but there is clearly room for improvement. It was a good idea not to start top case right away. I would have considered a result like this a degradation, not an improvement. So more experimentation was needed. I decided the hair bleaching product was not very well suited for my needs. I don’t know if the same would happen with the all such products, but at least this one's formula seems to produce the dry crystals.

Bleaching the mouse — A bucket pan full of H2O2!

I decided to let the power supply alone for the time being. Instead I replicated the 8-Bit Guy’s setup with liquid hydrogen-peroxide solution on the stove top to “cook” the key caps and the mouse, which I had taken apart and cleaned in the meantime, too.

Some googling suggested hat hydrogen-peroxide solution could be bought in pharmacies in concentrations between 3% and 30%. Apparently most of the stronger hair bleaching products contain around 12%.  

I went to three different pharmacies. In the first two, without only very vague explanations, they offered maximum concentrations of 3% and 6% respectively. Only in the third one did they explain to me, that around the beginning of 2017 there was a change in regulations, requiring sellers to document who bought the stuff and for what purpose, for anything 12% and higher. To avoid the paper work, most pharmacies just stopped selling these concentrations to anyone but business customers. I have no idea why they didn’t just tell me in the first two, but even if they had had it on sale, the prices would have ranged somewhere between outrageous and ridiculous (30€ per liter, at 6%)!

Fortunately I found an online shop that conveniently offered a “six-pack” of 1 liter bottles of 11,9% ๐Ÿ˜ H2O2 solution for a very reasonable total price of 20€, including shipping.

H2O2 bottle. 

I decided to start with the mouse, using the same temperature as for the power brick, just this time completely submerging the plastic in the solution on the stove top.

Mouse shell in H2O2 solution, in a pan. Thermometer showing circa 60°C.

Controlling the temperature turned out to be even more challenging. To prevent the solution (and the plastic along with it) from overheating, I had to turn the stove to its lowest setting and move the pot way off-centre, so that only a small portion of it was actually receiving any heat from below.

Pan on stove top, moved way off center for less heat exposure.

With this arrangement — the extractor hood above set to full, and the kitchen window wide open — I waited, checking the temperature and the plastic color regularly. After the first hour, virtually nothing had happened, but little bubbles forming. However, by the time about two and a half hours had passed, the yellowing started to disappear visibly.

After 4 hours the plastic had changed its color enough for me to consider it “original” again, so I turned off the stove and took the mouse out of the hot liquid with some pliers. I rinsed all parts with lots of warm water. 

Mouse top shell being rinsed, held by kitchen pliers. Underside view.Mouse top shell being rinsed, held by kitchen pliers. Top view.

Finally, see this before and after comparison. The first picture was taken right before the procedure began, second one right after rinsing. There is some moisture left between the mouse buttons, so it looks a little darker there in the photo — it actually isn’t.

Mouse shell parts, before bleaching, on white paper for reference.

Mouse shell parts, right after bleaching, on white paper for reference.

The improvement was pretty exciting and got it very close to what I would consider original color. Turns out, though, that even after taking the parts out of the solution, rinsing and drying, the bleaching reaction did not stop immediately. When i looked the next morning, the mouse had become quite a bit lighter still, even lighter than ideally I would have wanted. It does not look bad, it is just not as beige as the Amiga originally was:

Mouse shell. Upper case. 12 hours after bleaching, much brighter. On white paper for reference.

More lessons learned

With the mouse done, here are a few more take aways:

  • The submersion method yields very even effects — just as expected.
  • Pick as small a pot as you can — you’ll need less liquid to cover the parts.
  • You want really good ventilation. Standing right next to the pot for a while made my eyes burn. My wife complained about her throat getting sore.
  • Controlling the temperature is not trivial. This is a consequence of the small amount of liquid and the comparatively low desired temperature (in contrast to what the stove is designed for: cook food) Hence, a thermometer is a must have.
  • The bleaching continues for quite a bit, even when the plastic is taken out of the solution. Factor that in and take parts out sooner rather than later.
  • Don’t reach into the hot solution with your fingers ๐Ÿ˜‰
  • Rinse off with warm, not cold, water. I am not sure this is really necessary, but I figured it would be better than exposing the plastic to a temperature shock.

Armed with this new knowledge, I was confident it would also work for the key caps.

Bleaching the key caps

As laid out in part one, the key caps had already undergone a session of soaking and scrubbing in warm soap water. So they were ready for their bleaching bath.

The setup was exactly the same as for the mouse. Just enough hydrogen-peroxide solution to cover them all. However, due their shape and size, the key caps tended to float, so at least those closer to the surface were not fully covered all the time. To ensure they would still get the most even treatment possible, I used kitchen pliers to turn them all upside down.

Key caps in hydrogen peroxide solution, in a pan. Face down. Small bubbles.

Notice that I removed the metal braces from the larger keys — I did not want to risk corroding them. Some keys would turn around on their own, especially with the little bubbles forming, so I needed to slightly shake the the pot every once in a while to get rid of them and then ensure all caps were face-down again.

With the experience gained from bleaching the mouse I took the keys out about 45 minutes earlier, after just a little more than three hours.

Key caps being poured into a sieve, for rinsing.

In the pictures you can clearly see the special keys having a nice contrast with the letters and numbers. Here are the before-and-after shots, In the top right corner you see the floppy drive eject button, which I threw in, too.

Yellowed Key Caps, before bleaching. Laid out on white paper for reference.Key Caps, right after bleaching. Laid out on white paper for reference.

Interestingly, similar to what I observed with the trap door bay, plastic parts that did not suffer from yellowing before did not seem as receptive to the bleach. You can clearly see this in this detail shot of the space bar.

Key Caps, right after bleaching. Close up angle on different discoloration of the space bar. On white paper for reference.

I let everything dry on a cloth over night, before putting the caps back into the keyboard. There are only very few things to look out for when doing this. First of all, remember that there are two special (smaller) springs that go under the space bar, in addition to the center one which is the same size all others.

Space bar, being put back onto they keyboard, springs on the underside. Close up.

When putting back the metal braces under the larger keys, I noticed that they would not move as easily as before. This is because the bath in the soap water had washed away the grease that makes sure there is no noticeable friction. So I added some synthetic fat to lubricate the points where the braces a hooked into the white receptacles under the keys. For this I used the stuff that came with my coffee machine, because it does not damage plastic over time. WD-40 would not be well suited here. If you go through this procedure, make sure you use such a non-aggressive lubricant.

Return key. Underside. Lubricated metal brace receptacles highlighted.

Lastly, just as some keys had takes more force to pry off the keyboard base plate, some also took more pressure to go back in. At first I thought be springs were not equally sized after all, when I saw several keys stand out about 2 millimeters higher than their neighbors. But pushing them down just a little more decidedly made them audibly click back into place.

Keyboard with a few key caps placed back. Mostly empty still.

I started with the larger keys, because that way you have enough room to work with the metal braces. When all keys were back in place, I put they keyboard back into the case to see how it looked. At that two things became very obvious: First, even though they had spent almost an hour less in the solution than the mouse, the “after-bleaching” was still significant. The regular keys had become almost white, with the contrast to the darker keys significantly less pronounced. But more importantly, it was now very clear that I would now have to come up with a good way to treat the top and bottom case parts ๐Ÿ˜ฏ.

Bleached keyboard, in still yellowed Amiga case.

A report of how that went will have to wait until next time ๐Ÿ™‚.

Sunday, December 24, 2017

Amiga 500 Restoration

About 6 weeks ago I got the somewhat crazy idea to — just for fun — play some Amiga games. At first, my plan was to set up a Raspberry Pi 3 with an Amiga emulator, after stumbling across Dan Wood’s YouTube channel. Even though I even have a Pi 3 lying around unused at the moment, seeing Dan holding that Amiga 500 in his hands at the beginning of the video, I got all nostalgic and decided I could at least do a quick ebay search to see how much they go for these days.

Turns out, I could get my hands on one, including a memory expansion card, mouse and power brick (and a brick it is!) for  just 60€. Turns out, I would end up spending quite a bit more in the end, but still it was (and still is) a fun experience.

The whole story is probably way too long for a single post, so I may end up splitting this into at least two parts, but I feel it is necessary to write this down if only to remind myself about it in the future :-)

Update, 2018-01-05: Part Two “Amiga 500 Restoration: Retrobrighting I” has been published.

The Amiga 500

Amiga 500, yellowed plastic , straight from ebay

There’s quite a few Amigas on ebay, especially 500s. Considering they were the cheapest and thereby most common model, that makes sense. I god hold of one for 60€ plus shipping. I could have gotten one in better condition for more money, but I wanted something to try the technique of retrobrighting on, so I was just fine with the yellowed case.

It arrived in a big box with lots of packing paper, covering the mouse, the power brick and the Amiga itself, plus some cable I couldn’t immediately identify. Only later did I remember it is an RGB video cable. I also did not remember the power brick to be so heavy. It was equally yellowed.

The picture above was taken under fluorescent light, so the color representation is not exactly accurate. The next photo was taken in daylight on an overcast winter day, with a white sheet of paper for reference. I then used on the Mac to set the white point to that paper. This allows a better side-by-side comparison later.

Fullsizeoutput 6392

Having neither a suitable Amiga monitor like the venerable Commodore 1084S, nor an adapter cable to hook the machine up to my Panasonic plasma TV via the SCART connector, I could only do a very superficial health check. I hooked the computer up to power and turned it on. After about three seconds the power LED hat come up to full brightness, and the disk drive began its expected regular soft clicking every two seconds or so, looking for a 3.5” floppy. So the machine seemed healthy for the moment.

Cleaning inside and out

While the yellowed case is a consequence of age and UV exposure and cannot be removed superficially, there was also quite a bit of dirt and grime on the case, the keyboard, the mouse and the power brick. So I decided to take everything apart and give it a thorough cleaning. What follows are the steps to disassemble and clean everything. 

Taking off the top case

The top case can easily be removed by unscrewing 6 screws on the underside. On some Amigas these may be Philips heads, but the more common variant seems to be with Torx screw heads. With a little care you can open them with a flat head screw driver, without damaging the screws. If you have the appropriate Torx screw driver, even better, of course.

On left and right side there are plastic clips on the inside, holding the top and bottom case together. Be careful when taking off the top part, because they are easy to break. Carefully wiggle the top case left and right to get one of them to slip out.

IMG 5056IMG 5057

Once open, you have the keyboard and the RF shield in front of you. Be very gentle when handling the top case. Even though is won’t break apart too easily, due to the big holes for the keyboards, it lacks a bit of structural integrity unless handled by holding it on the more massive part where the ventilation slits are. Also take care to put it down gently and on soft undergrounds. I learned the hard way and chipped the two rear corners when trying to lean it against a wall and hit the ground at a bad angle.

Removing the Keyboard

To clean the keyboard, I recommend first removing it from the case. It has to come out for the later steps anyway. To do so, disconnect the cable from the motherboard by pulling it straight up through the hole in the shield. It should be rather safe to pull on the cable — the connector isn’t that tight on the board, and trying to get your fingers or some tool through the hole is probably a bigger risk of damaging something.


Remove keyboard

Don’t worry, the cable is keyed, so you don’t have to write down the orientation: Looking at it from above, there are 4 wires on the left, and 3 on the right, separated by an empty slot. The connector on the board has a missing pin there, too, so it is easy to reattach later.

IMG 5059

Once the cable is free, you can slide the keyboard slightly from under the plastic latches at the very front of the machine. Then just lift it up. Notice the small spongy tape pieces between the keyboard metal base plate and the plastic latches. Depending on the age and condition of the Amiga, those might come off. In my case, the outer two stayed in place, the middle latches didn’t have any. I am not sure, if there used to be four. If they detach, I recommend replacing them, because I suppose they are intended to keep the keyboard more silent and as a strain relief for the plastic latches. 

IMG 5058

On right hand side, just beneath the power / drive LEDs, the keyboard rests on a similar little sponge. This one came right off when I lifted the keyboard up. This one, too, should be replaced, even though, of course, none of them are exactly mission critical. I did that with two layers of Powerstrips, leaving the protective tape on on the upper side.

Please note, that I only applied this at the very end of the restoration process, because in the meantime the Amiga casing underwent several other steps, which would have removed or at least damaged that new cushion.

IMG 5063IMG 5064

When putting the keyboard back in later, carefully slide it back under the front latches. The metal base plate has a notch indicating the middle. Align that with the screw hole in the bottom case.

Removing the Key Caps

Lots of grime and dirt accumulates on and especially under the keys. To clean the keyboard thoroughly, the caps must be removed. The regular sized keys (including the F-Keys, Del, Help and Ctrl) can be taken off more easily than the larger ones (Return, Shift, the Spacebar, etc). You will often find people recommending to use a flat head screw driver to slide under a key cap, using it as a lever to pop the key off. While this works, I do not recommend it. The reason is that screw drivers are metal, and the key caps are 30 year old plastic, which got somewhat brittled over time. I learned the hard way that you cannot always tell how much force you can apply, before something breaks. This meant I had to repair a cracked “J” key (Super glue from the inside of the key was used to put the broken piece back in place. Once it had dried, two additional layers of flexible glue were added to increase stability).

IMG 5053

What I found worked way better than metal were wooden skewers. They are flexible and tend to break when you apply too much pressure. I managed to get all remaining keys off without any more damage using this method. 

This picture shows the the little hill each key rests on, as it stands above the plastic base. Having that before beginning would have helped a lot to understand where to apply force, so I’ll post this here for posterity. To get a key off, I tried to get two skewers underneath as shown by the parallel lines, and then to gently lift them upwards a little bit one at a time, alternating between the two. Most keys came of after just a few nudges. Be patient, they will eventually come loose. Some particularly stubborn ones took a few broken skewers. If they don’t seem to move at all, try to put a skewer close to the middle and carefully lift there. The thing that I found to be most important was to get the skewers to rest on the elevated part.

IMG 4600

Underneath each of the regular sized keys, there is one metal spring. Be careful not to lose any, they make the keys come back up while typing. I placed them in a bin with a lid for safekeeping.

IMG 4592

The bigger keys are a little more difficult to remove. They have metal braces underneath them to give them more stability and prevent wobbling. They can be popped off using the skewers, too, but you cannot just lift them off the keyboard afterwards. Instead, the braces need to be carefully removed either from the black plastic keyboard base, of from the key cap themselves.

I went for what I now consider the worse option and unclipped them from the base plate. In retrospect I think this is too risky, because for once at least some of them were really hard to get unclipped and you risk breaking off pieces of the assembly. Second, because you must be very gentle and not bend the braces. So if I were to do this again, I would use tweezers and unhook them from the underside of the key caps, which might be a little more fiddly, but requires much less force.

The pictures show the braces for the Return key, and where they are attached to the base plate, and on the underside of the key.

IMG 4781

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The space bar has three springs. Notice that the middle one is the same size as all the other keys, but those on the left and right of it are slightly shorter. This is important when reassembling the keyboard later.

IMG 4790

Cleaning the Keyboard Base Plate

Once all the keys were taken off, this is what my keyboard base plate looked like. All in all not too gross, mostly lost of dust and some sticky stuff.

IMG 4594IMG 4593

The first round of cleaning was just a brush and a handheld vacuum cleaner. This got rid of most of the dust and loose dirt. In my case, there was nothing left on the keyboard that could have been sucked into the vacuum, so I was not all to careful when doing this. If you leave the metal braces on there, make sure those are not ripped off.

IMG 4596

Finally I used paper towels and warm water to remove everything that more sticky, and finally went around all the key domes and the nooks and crannies of the metal brace holders with isopropyl alcohol and cotton swabs. The end result looked like this:

IMG 4599


Cleaning the Keyboard Caps

There was no glory in cleaning the key caps. They very unceremoniously were all dropped into a small bucket with warm water and some dish cleaning liquid to soak for a few minutes. After that came the laborious manual part, rubbing them with a kitchen sponge. Make sure to only use the soft parts of the sponge, should yours have a more scratchy side. That one would most probably leave visible marks in the otherwise very smooth plastic.

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IMG 4649

Some of the key caps had some nasty stuff stuck on the bottom side, which I had to remove with a tooth pick. The whole cleaning easily lasted for 30 minutes, because I wanted to make sure all sides of the keys were thoroughly cleaned in preparation for bleaching them later. The photo above shows how much the keys had yellowed, especially when you look at the space bar. You can clearly make out where the adjacent keys had kept light away from the side of it. Their shape is clearly visible in the “whiter” parts. Well will come back to this later.

Cleaning the RF shield

With the keyboard out, the RF shield is the most visible part now. I gave it the same treatment with brush and vacuum cleaner from the outside, including the space between it and the bottom case. This removed most of the dirt already.  Then, with it still in the case, I wiped it off with a moistened paper towel and some glass cleaner. The dark spots seen in the photo are rust, so they can't be removed easily. 

IMG 4604IMG 4607

Removing the RF shield

The get to the mainboard, next I removed the RF shield from the case. It is attached to the bottom case just a few screws that are easy to get to. On the left, there is a separate metal bracket across the expansion port. I carefully removed that, too, and put it away to prevent it from getting bent.

To actually take the shield out, a series of small metal latches need to be bent upwards. They connect the metal tray the mainboard sits on with the RF shield. I just followed the edges of the RF shield and carefully bent them upwards with a flat head screwdriver.

 IMG 4606

Once they are all bent up, the shield came off with a little wiggling. Once out of the case, the shield is rather wobbly and should be put away safely to prevent accidental bending and deformation.

Cleaning the mainboard

With the RF shield out, the mainboard lay before me, with fond memories from the 80s… and with lots of dirt, potentially also from the 80s…

IMG 4608IMG 4611IMG 4616

Again, this was cleaned with a brush and the handheld vacuum cleaner. Even though with the perspective in the photo does not really show it, I took particular care to not get the vacuum too close to the board, because I did not want to risk it ripping anything off the board (even though it was set to low power), and also to prevent too much electrostatic buildup.

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It took a while, but I was pleased with the result.

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Somewhere along the way I removed the floppy drive, because it covered part of the board.

Removing the mainboard


With the mainboard now clean, I removed it from the case, too, to be able to clean the bottom case. The board sits on a metal tray, which makes removal quite simple. The only thing to be careful about is to pull the board a little forward to get the external connectors free from their openings in the back wall of the plastic case. Once they are clear, the whole tray can be taken out. I also took the mainboard out of the tray for a moment, to be able to clean out the dust from underneath it. Once that was done, I put it back immediately, because it serves as a good protection for the bottom side of the board.

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Cleaning the case parts

With everything removed from the case, I scrubbed the top and bottom cases with warm water, soap, an old toothbrush, paper towels, isopropyl alcohol, and microfibre cloths. Only for a very few stubborn spots I had to rub a little harder with some mild abrasive. That’s the white stuff you can see on one of the photos. Once done, I rinsed everything off in the shower and let it dry over night. While there are pictures of the dirty state, for some reason I did not think of documenting the finished cleaned state ๐Ÿคจ

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At this point, I could have have just reassembled everything in reverse order, and frankly, that would have been a much better state than before. However, there were a few more things I had in mind. But those will be the topic of another post.