Amiga cleaning time

Northern spirits

Amiga 500 and manuals.

The midsummer night's sun beckoned -- "Take out your Amiga 500 and check for battery leak damage. Do it now." So I did. I covered up the top of the case in this photo to cover a rather diverse gathering of filth. The Amiga 500 manuals are in full color and with lots of technical information. The A1200 ones were unfortunately in grayscale.

Amiga 500 motherboard.

Fat Agnus, Denise, Paula and Gary are still having a party in there! No battery on mobo as far as I can tell. Quite a beautiful board, but I wish the chips had little logos and figures printed on them. As a kid I wanted to do a 3D game where you ran around on a computer chip, meeting its inhabitants, and I remember making something very crude in 3D Construction Kit. Realized that I needed to learn assembler, bought some books, but didn't learn much.

This is... VAAAARTA!.

Oh, there you are you leaking bastard, pissing all over my expansion memory.

Amiga 500 motherboard.

I crazily thought I might be able to simply migrate the socketed trapdoor RAM chips to the empty sockets on mobo if the trapdoor circuit board is done for, but it's a complicated affair. I have a Rev 6A board with a 8371 FAT AGNUS, which apparently is what sits in PAL versions. This Fat Agnus can only address 512kb but you'll notice that it sits in a socket which facilitates upgrade. I mostly use my A1200 with a Blizzard 1220/4 anyways so I'm not gonna bother with the A500. I might use it for testing low end game projects.

Amiga 500 expansion memory battery damage.

Clipped off battery as my soldering iron would not heat up. Scrubbed area with lemon juice as advised elsewhere, but didn't want to overdo it so the damage still looks nasty. The battery only keeps the clock running and isn't needed for the expanded RAM to function however.

Amiga 500 case.

I don't know anything about which chemicals to use when cleaning up plastics, but I did some seemingly successful tests with a window cleaner which contains denatured alcohol... and some perfume! My Amigas had no particular smell though as I do not smoke, nor have I stored them in a mold infested attic or garage. Not going to bother with Retrobright to reverse the tan (edit: or so I thought). Had to be careful with alcohol around the C= label as it takes off the gray (edit: also, window cleaner contains ammonia which according to some can have nasty effects on some materials, though I wash off quickly with water and have never noticed any marks).

Mac Games.

When something is less than 2 meters away from you and you still can't find it, you become acutely aware of your lack of omniscience. The RF-Modulator has gone into hiding. I know I've seen it around, but now it's suddenly gone... now when I need it. Indeed, you know the exact feeling.

I did find a couple of Mac games instead. Circa 1995... those were the Mac years for me, though I was still using my A1200 regularly for a few more years. I wonder if I could play these games through a Mac emulator. These are not bad games.

System 7.5 running in Basilisk II.

I downloaded Basilisk II (68k Mac emulator) and got System 7.5 installed on a hard drive file after some trouble (peripheral programs and files were needed). Also, people who upload StuffIt Expander in a stuffit archive can, you know, stuff it (apparently). Oooh, looks like you can paste 64px Desktop Patterns into the selector program, but the images dither into what appears to be a 256 color palette (and not the system one as far as I can tell). Just as I was about to save this palette Basilisk blue-screened Windows 7, so I abandoned the project.

I'm forgetting something... Oh, the games. Well, the CD drive driver won't work in a 64-bit environment, but apparently you can make ISOs and load those. More programs to install and I sort of lost the appetite. Hmm, weren't I doing Amiga things? Right, the search for the RF-Modulator.

Amiga mice.

Maybe I did put some Amiga stuff up on the attic after all?

Found the broken mice! And the culprits >:(

Three Commodore mice and an Atari/Amiga mouse. On a round Commodore mouse, you'll find the screws under the label (which can be carefully removed without damaging or bending it noticeably). Pull back top half (like you load a pistol) to unsnap. The micro switches can be replaced somewhat easily and aren't expensive.

Amiga 1200 case.

The A1200 was quite gunky as well, so I gave it the window cleaner + toothbrush scrub. Only some very subtle white patches around the keyboard holes remain, and that's from the shadows of the keys (yellowing comes from light exposure iirc).

Amiga luxury berth.

With no RF-Mod in sight, I'll just have to let the project rest for a while. Top: A1200 with the lone functioning "Naksha" mouse. Mid: A500 showing its innards. Bottom: Extra drive, Amiga Sampler, 亀の恩返し ウラシマ伝説 (famicom), random 3.5" HDD and dead 2.5" Conner HDD, Game and Watch games (My dad visited Japan when they were still a new thing, came back with DK). DKjr has the score 772 noted on it. I used to open these and replace the levels using overhead film and pen.

Amiga Tank Mouse.

Update! Managed to replace mouse buttons on my original Tank mouse using new Panasonic micro switches. They only have 4 legs and are a bit taller, but the legs can be (un)twisted into place. I had to cut some plastic off the button + rods which meet with the switches. The common 6x6 tactile switches fit, but are too hard/clicky for use in a mouse.


Not finished, but works!


Forgot to turn off edge-improvement on TV, but otherwise I see no notable video signal artefacts. TV scaling makes picture a bit blurry, but on the positive side, it fixes the hires flicker. I have 2+4M or RAM (courtesy of Blizzard 1220). Icon theme is still WIP. Computer reboots in 3 seconds and doesn't touch drive unless I do something or there is a virus doing something (fortunately very unlikely these days).

Amiga 1200

Adventures with "retrobrighting". Before shot. It's easy for a camera to lie about exact hue, but this is the same case as in images above.

Amiga 1200

Results seem to be a mix of the % hydrogen peroxide * sun power * time. Stronger % can be dangerous and even low % stuff gives nasty blisters. Don't dilly-daddle with protection. Can't believe this stuff is used in the hair. I used a mix of 3% wound cleaning HP (a clear liquid) and 10% hair salon cream. This makes it stick. Too creamy & uneven might produce marbling patterns on the plastic.

The hair stuff I got came with a bunch of other packages (boosters) aside from the white cream. I tried those (mixed in) on another test surface and they proved destructive to the plastic. (Edit: I bought a PC Engine and a Super Famicom which have probably been retrobrighted with too strong stuff, giving the plastic a brittle, pitted or wipe-mark'y look. Some people claim retrobrighting is bad for the plastic but I believe it's down to plastic type and HP% and bad additatives.)

Another lesson learned: Apply stuff indoors, wrap out, place on junk table. If you work on the ground outside, dust, bugs, and in my case, red mites, will invade and cause a mess. The red mites can even cause orange stains.

Amiga 1200

Again, as you can see, exact hue depends on camera and lighting. I've done the top case and the arrow keys here. It's strange to see the yellowed keys stand out so much now. Was it really this bad? The keys actually have inverted shadow gradients burned into the sides. Waiting for a proper key-puller. Oh, I did the mice too... well, actually, one was done using...

UV UV-array: UW-1200! 12 for the 12 LEDs and 00 for the 100 Ohm resistors. UW for Ultra Weak. More on that later. I used a generic 5V USB/Charger supply but made the rest. Component tester gave me a 3V drop on LEDs and because I wanted max shine (without killing LEDs) that was (5V-3V) / 0.020mA = 100Ohm (parallel configuration).


I built a reflective house. UV LED light is partially invisible and can apparently be harmful to the eyes as it doesn't trigger blinking/squinting. Better safe than sorry - I pulled the plug on every checkup. After a test run, this device proved to be pretty weak and I believed it didn't actually work at all for a while. I did the mouse cover in the sun instead. Later I noticed a yellow side on the bottom case, and with no sun out, I left it in the UW-1200 overnight. In the morning, the yellow had been purged. I had it standing on its side so it was really close to LEDs. Temp-gun told me the board gets a little warm (+15C), but not the housing/subject (+5C).

Datic Naksha mouse

In 199x, I bought this DATIC Pro (store-demo version) Amiga mouse after having had bad luck with other mice (...I simply didn't know how to clean and repair them). When I opened the box, there was a Naksha logo on the mouse. Never looked into that mystery. It came with a cable extension/adapter, so... maybe an Atari mouse? Regardless, it was a very good mouse for the time. Is. I still use it with my A1200 over 20 years later. I never quite liked laser mice because the lack of momentum when lifting. Judging by the box photo, it was never cream color. This was after the first treatment, I did another one later, in the UW-1200 that by then had re-earned some of my trust.

Decided to retrobright the A500... maybe just the case? Noticeable effect, but obvious that I need to do the keys as well. Ordered a keypuller which arrived a month later...

Keyboard-time already, in the next paragraph??! It was quite time consuming to pull the keys, but not as risky as I thought, thanks to the handy keypuller. However, I saved the long keys for last and used my fingers to gently lift them. Underneath are some plastic bits that hooks onto metal brackets. It's best to lift up these keys and angle them, wiggle out the spring and then pry the (springy) metal bracket open about half a millimetre, then slide the key out. Helps to have long nails. Take a reference photo before pulling the keys, by the way. 96 springs, in case you wonder.

Found a Sharp QT-15 in a thrift/charity store. Don't really care for it, but I did have a red double-deck one back then so I had to get this one. It was initially very grimy and noticeably yellowed. It didn't retrobright very well despite two mid-summer days of treatment. Always hard to tell though, and harder to show.

Anyways, back to the Amiga 500 keys. I brushed them with my 10% cream + 3% medical (liquid) mixture. Too much work, so every hour or so I went out and sprayed them with a nozzle, taking care not to breathe or get it on me. Turned them around a lot and massaged the fluids around.

Retrobrighting so far has always been a bit destructive. I fear I may have overbaked the keys slightly. They're back to their original colors (judging by their undersides), but the darker keys experienced some slight marbling. Maybe they need to be in a bath. Maybe I should've pressed the wrap flat on top of all keys (no bubbles) (edit: this seems to have been the problem). I was thinking it could be a very superficial microstructure effect as it doesn't show when wet, so I decided to give them a light circular polish using Mr Muscle ceramic cleaner (abrasive). Imagining it did a little good... maybe? Interestingly there was no marbling on the untextured sides of the keys.

When I did the A500 & 1200 cases I got some streaks of slightly more gloss areas which shows only in certain reflective angles. My bet is that using weaker stuff and massaging/rotating a lot helps to average these artefacts out when using the plastic wrap method.

Ready to reassemble the keyboard. Here we can see the metal bracket under a long key. The white plastic things can be pulled out of the key but they look brittle. Also, they were gunky, so I think some grease had been used. I reapplied some weapon grease I had, on the ends/tips of the brackets. I inserted one end first, pulled the bracket open half a millimetre and slid the other end in, then fiddled in spring underneath. All keys need to be *clacked* in place (though some make more of a *thump* or *snap*).

QT-15 down to maybe 40% of original tint. The original white inside deck is somewhat noticeable to the eye. It's harder to brighten certain kinds of plastics, I guess. Also, this thing was full white, unlike the Amiga where residual yellow can hide. I think the red print on top may have faded a bit during the treatment. I was careful not to scrub it hard with any cleaner. She still works, by the way. Guessing 1980-85 vintage.

Outdoors things always look a bit whiter, cleaner, to the eye as well as camera. Blue sky mixing in, and light overexposure? When I move things indoor I often notice yellowed bits, but in this case I kind of nuked the keys all the way back to factory.

The keys stick up a bit too much as they are resting on the opened shielding. I assume the RF-mod is partly the reason why there's a shield, but I lost mine. I'm thinking of getting rid of the shielding since I have a custom SCART cable that might be working with the video port (assuming port is same as on A1200). Shielding traps quite a bit of heat in my A1200 at least. Should put a fan in that one, and with shielding gone I could heatsink some ICs. Chips may be within limits... limits probably based on like a 5 year life span and no shenanigans by ageing surrounding components.

Indoor shot. Here we can almost see that the keyboard is very slightly brighter than the case now. Quite happy overall, despite the marbling.

... I wonder if it still works... The caps look fine, and battery damage was on memory board which is being repaired. My A1200 PSU works, but I have not checked the A500 one (got some more juice iirc).

While the A1200 seems to have the same keyboard layout, there's no circuitry, but instead a ribbon cable. I made a wire tool to get (fish) the clamp holding it out. This time I used two wooden paintbrush shafts to lift/lever up the long keys that I saved for last. Left Shift was missing both a metal bracket and the two white plastic thingies. Assembly error or cost saving?

This time I'm watching the plastic wrap like a hawk for bubbles on top of the darker keys. It seems like the brightening is accelerated where the wrap contacts the keys, because I think the sides are un-tanning slower. Maybe the HP evaporates there? I keep massaging the keys around just in case. A bath probably gives a more even coat but I only have a small bottle of stuff. Hmm, I saw someone using zip-lock bags filled with fluid. Might be more economical.

Spilled some on the ground - it formed foam in the open air.

So when about 70% done I figure out that rocks beats tape. A lot easier to loosen when I need to reapply HP (I just sprinkled the 3% fluid over this time). It also allows the wrap to cling loosely to the wet tray and I can mush the keys around easier. When using tape and stretching the wrap, wind gets under and I think the HP evaporates away from the sides of the keys. Using tissues to push air bubbles out and also avoid touching film too much (mine's got a few holes), and wiping accidents off me. Or wiping mites off the keys - somehow those keep getting in there.

I wimped out and underbaked the keys this time. There's still some yellowing visible as a gradient down the (once) window-facing sides, but it's surely an improvement... relying on memory. Forecast says not sunny tomorrow and this is becoming a chore. Hesitant. Oh, notice there's no marbling on the darker keys. My precautions seem to have worked!

The keys do match the case pretty well, so I decided to put her back together. As you can see, there's some subtle gradients on the case as well, around the key holes.

Amiga 1200 spacebar

Underneath the spacebar, in case you wonder. Only one switch right at the middle holding it in place. My red MSX had a very similar construction. The two flanking springs are of a smaller variety.

Amiga 1200

It'll have to do. The darker keys still have a very slight green tinge (compared to bottom) and the whole the light plastic is a warm white, but easy to mistake for neutral without reference. Compare with before though (a bit up)! Have not done the bottom of the case, or screwed together as I access the drive a lot and the thing gets a little hot near the drive for some reason.


Some other hardware pages

Amiga HDD - Amiga cleanup - Amiga pixels - SBC - Assorted - MSX - Acorn project - Amstrad project, etc. - ZX project - Assorted - Electronics Endeavour

Art by Arne Niklas Jansson