Amiga 500 Restoration

Discussion in 'Retro & Arcade Worklogs' started by iMic, Apr 28, 2018.

  1. iMic

    iMic Member

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    To avoid cluttering The Amiga Thread with information about this build, I'll split it off and post the details and ask questions here.

    I'd like to acknowledge tkc8800 as the previous owner of this machine, as he made efforts to restore it from poor condition to the reasonably decent condition I received it in. I'm just hoping to carry it through to completion.


    Anyhow, I have a real tendency to bite off more than I can chew when it comes to ongoing projects. This machine ended up shelved for around a year since I acquired it, and in recent times I've decided I should probably thin out my collection and active projects with the hope of actually finishing some. This machine stood out as one I would like to keep.

    Here's the lowdown. It's a Commodore Amiga 500, 1988 production run, pretty standard affair. The machine had been stored somewhere for a while and accrued a layer of dirt, rust and corrosion on the outside, inside and on the motherboard. The Floppy was packed with dust, and the trapdoor expansion clock battery had leaked. Not to mention the power supply was missing, a replacement I sourced was dead, the mouse cable was cut off, and soldering on a replacement connector revealed a faulty encoder wheel sensor.

    Off to a great start.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]


    Last December I started to claw this machine back from the edge. I contacted some members in the Adelaide Amiga clubs and sourced a replacement mouse and power supply for it. There's no pictures from around this time, but essentially the machine would power on, but not boot, and when I disassembled it to clean the drive, I discovered corrosion around the sidecar expansion connector and trapdoor expansion board, and surface rust on the RF shielding.

    The machine went back into storage.


    Because I have machines around I almost never use, I thought it made sense to filter down the collection and let someone else enjoy the less frequently used ones. I thought about whether to continue with the Amiga 500 and decided I would, if only because the Amiga community is so enduring, and it's a machine I had no experience with.

    But that motherboard needed servicing. No point repairing the rest if the board was toast. I started cleaning around the sidecar expansion connector with alcohol and an eraser, and managed to remove the corrosion from the contacts.

    [​IMG]

    The contacts are pitted, but intact. The contacts aren't completely smooth, taking on the contours of the texture of the underlying circuit board, and as such the damage isn't anywhere near as bad as it looks. As this is a restoration of course I'd prefer they be in perfect condition, but all in all, not enough to write off the otherwise functional board.

    Removing the corrosion from around the screw post ground planes is harder. Some minor metal polishing could bring these up to a better condition, but I need to ensure that it won't strip the board first.


    The RF shielding was more of a problem, covered in patches of brown surface rust and oxidation on both the top and underside of the cage.

    I took these out, cleaned them to remove excess rust and corrosion, and soaked the plates in Evapo-Rust for a couple of days. It removed the rust, but couldn't do much where the corrosion had damaged the plating.

    [​IMG]


    Still, I suppose it could be worse. Even so, I'm seriously considering having these pieces professionally re-plated in either Zinc or Nickel, whatever closest resembles the original finish or achieves the best result when factoring in that cost to durability ratio.

    Hopefully more to come on that front soon.


    The plastics are probably the most impressive piece of the machine as-is. They're in damn fine condition, and the Amiga 500's trademark rear fin arrangement looks seriously sharp. That said, those fins attract dirt and this machine was no exception. So into the detergent wash they go.

    [​IMG]

    And before anyone expresses concern, this is about the weakest household dish soap one can buy. But the results were good, to say the least.

    [​IMG]

    This is where someone would normally Retrobright and de-yellow the case, but it doesn't need it. Using the areas under the half-torn and now removed warranty-void stickers as a control, the plastics are exactly the same colour under the labels as they are in the exposed areas.


    Now in the home stretch for this evening, I removed and re-socketed the ICs, disassembled the floppy drive to remove the dust and carefully alcohol swab the heads, and connected the board on the bench to see if the machine fired.

    And it did.

    [​IMG]

    It's connected via a Commodore A520 RF Modulator. It sucks hard. But it proves the machine works.

    And the one component that doesn't need any further attention is the keyboard. It's pretty clean underneath the keys and it worked first time.


    So, onto the game plan for the next stages of the build:

    • Have the RF Shielding and Floppy Cover professionally re-plated in Zinc or Nickel
    • Source some DB-23 connectors and make VGA, RGB and RGB-SCART Video Cables (can make these myself)
    • Replace the Trapdoor memory expansion card (and bodge-repair old one as a spare)
    • Clean up the motherboard ground planes (if possible)
    • Make data transfer easier (Gotek or HxC Floppy Emulator w/ External Cable & DF0 Selector, no case hacking required, although feedback and advice is welcome here)
    • Make network connections easier (Serial connection to Mac/PC with Hayes modem emulation and pass-through with TCPSER, to connect to BBSes or control newer machines via Terminal)
    • [Extra] Convert the faulty mouse to optical tracking
    • [Extra] Convert the faulty power supply to ATX internals

    Will post some updates as I have them. There's no fixed time frames for completing each milestone but I'd like to continue working on it fairly frequently if I can.
     
    Last edited: Apr 28, 2018
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  2. Grant

    Grant Member

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    Not sure how original you want to keep this machine, but there are modern accelerator boards give you an IDE bus so that you can use a CF card as a hard drive. Typically they go onto the sidecar expansion though, so you still can use a trapdoor expansion for extra chip RAM.

    Check out the plipbox, which gives you ethernet via the parallel port. There's many people that make and sell various pre-built ones.
     
    Last edited: Apr 28, 2018
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  3. HyRax1

    HyRax1 ¡Viva la Resolutión!

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    Excellent work! Looking forward to seeing the rest of your goal list completed! :thumbup:

    With the Gotek idea, if you upgrade the machine to Kickstart 2.x or above, you can boot a game or demo from DF1: but be wary that the poorer coders would sometimes hardcode the expectation that you would be only using DF0: which means it will boot to a certain point and then just stop.

    Alternatively, people have installed hacks to switch DF1: to be DF0: either permanently or via a toggle switch.
     
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  4. badmofo

    badmofo Member

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    Great commitment to what most would consider a lost cause. Personally I find that these sort of projects are the most satisfying and result in an understanding and appreciation of the hardware that wouldn't get otherwise, I hope it all comes together.
     
  5. flu!d

    flu!d KDE Neon 5.16

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    It's so white!

    My A500 is treated so carefully, packed up in a pillow case and wrapped in a towel and put on the shelf when it's stored away and always covered. Yet I swear that it's yellowed since the last time I packed it away.
     
  6. HyRax1

    HyRax1 ¡Viva la Resolutión!

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    I've been seriously been contemplating a replacement case for my A500. There's only so much you can do for an original case sometimes.
     
  7. flu!d

    flu!d KDE Neon 5.16

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    The problem is that you get a nice white case and then you notice the key caps have all yellowed!

    I've actually got a spare A500 case under the bed that I bought years ago, I should pull it out and see what condition it's in.
     
  8. HyRax1

    HyRax1 ¡Viva la Resolutión!

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    And therein lies the dilemma! ;)
     
  9. Grant

    Grant Member

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    The project that created the new molds for A1200 cases later did new molds for keycaps as well (the keycaps were for both A1200 and A500), and did a run of them on Kickstarter. They haven't arrived yet :)thumbdn:), but the molds have been finalised after a few revisions I believe. On the IndieGoGo site they've said that they'll do another run of the keycaps, which I assume will be shipped around the same time or before the A500 cases themselves, since they'd already have the molds.
     
  10. OP
    OP
    iMic

    iMic Member

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    Generally the rule I follow is modifications are fine, as long as they're reversible. As soon as a dremel or cutter needs to come out to install it, it's beyond where I'd want to go with a machine.

    I considered adding an accelerator like the Wicher 500i for this reason, with IDE compatibility and because it uses a standard Motorola CPU that compliments the stock hardware. Because of it's price tag though, it won't be something I consider until the machine is otherwise complete.

    The plipbox looks awesome. I'll look into it when the time comes. I'll still connect the machine via Serial at first, since it only needs readily available parts (and I can map phone numbers to network addresses in TCPSER), but eventually the machine ideally needs to be functional independent of another system, and that's when I'll look at getting one.


    I think that's what the DF0 selector does, switches DF1 and DF0 around as needed. Ultimately the aim isn't necessarily to run games just yet, but to allow the machine to boot into Workbench and move data around on something other than degraded floppies.

    I'm thinking about upgrading the machine to a newer ROM, but I'm curious here - is the Workbench version directly tied to the Kickstart ROM version? If for example I wanted the Amiga 500 to have its iconic high-contrast blue and orange desktop, would I need to retain the Kickstart 1.3 ROM and Workbench 1.x disk?


    It's getting harder to find and maintain plastics that haven't yellowed already. I'm thinking about giving the Amiga a spray over with some UV protectant, but need to test it on something else made of ABS first.
     
  11. flu!d

    flu!d KDE Neon 5.16

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    My A1200's perfect - Snow white and no yellowing whatsoever, even the key caps are perfect. A500's were never the same white as the A1200 even from new, the A500 was more of a cream color. What's got me stuffed is how the case and keys appear to have yellowed slightly even though the machine has seen no sunlight.
     
  12. nic55

    nic55 Member

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    I picked up an A500 last year that I've slowly been upgrading and having some fun with.

    Went with a Gotek as well, installed it to an external floppy case and upgraded kickstart to 3.0 so I could boot from DF1 (didn't want to hack up my case either). Very quickly ran in to the issue where a lot of games would not load properly from DF1, and also a lot of the software I wanted to run wouldn't load fully on KS 3.0.

    So as to not cut up the case any, I'm looking at adding a DF selector switch and a friend of mine is looking at burning some dual rom chips so we can select between KS 1.3 and 3.0 with a toggle switch.

    Some food for thought :)
     
  13. Flamin Joe

    Flamin Joe Member

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    You don't need direct sunlight in order for the yellowing process to start as a small amount of UV light will still be bouncing around the room. Had it been directly in the sunlight you probably would of had a badly yellowed case but because it received only a very minimal amount over the years you only have slight yellowing. You also have to remember that while UV light is the primary cause there are others factors such as heat which doesn't necessarily need to come from the machine itself. A room with no aircon over many an Australian summer would be ever so slowly "cooking" the plastic.
     
  14. badmofo

    badmofo Member

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    This is my concern - my stuffs are generally stored in a cupboard so no light of any kind, but the cupboard is in a tin shed which gets cranking hot during summer. I haven't noticed any yellowing of my retro machines though over the ~7 years or so I've had them. I suspect that if a case lasted this long without yellowing them its plastic is probably just not as susceptible as some. Low bromide? Some old keyboards for example have a yellow spacebar while the rest of the keys are OK, which I presume means that the composition of the plastic is different.
     
  15. flu!d

    flu!d KDE Neon 5.16

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    I believe this is exactly what happened. The A1200HD gets stored in a pillow case in the wardrobe where as the A500 was stored in a pillow case on top of the bookshelf in the study and the study gets warm in the summer as the sun set's on that side of the house.

    Looks like I might be doing a but of retrobriting!
     
  16. Flamin Joe

    Flamin Joe Member

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    I've seen the same with my PC's and keyboards, identical parts yet some yellowed more than others and it's even spread across the plastic so nothing to suggest it more direct sunlight than the others. One good example too, I've got an Atari PC XT Keyboard sitting right next to me on my desk of which the case is yellowing yet all the keys are in perfect condition like it just came out the factory! I've got another however which is yellowed all over, it's very much a lucky dip.

    I think your correct about the bromine level. I can't remember where I read it but apparently it wasn't an exact science and it could vary from batch to batch and manufacturer. It's funny to think about it but any plastic manufacturer back then looking to cut costs by mixing the bare minimum bromine was actually doing us a favour later down the track!

    I think collectors who try to emulate museum like conditions by having everything in a temperature controlled room lit by non-UV emitting light are onto something! Has anyone got this weeks lotto numbers? Cheers! :D
     
  17. OP
    OP
    iMic

    iMic Member

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    I took the EM shielding plates to a metal plater for assessment. He took one look and said there was nothing he could do. The process of achieving a presentable finish after plating requires some polishing, and because of how thin the metal is, polishing it would warp it.

    I'm querying this with some other shops, and am prepared to accept any decent finish - polished, reflective, matte - whatever is achievable.
     
  18. flu!d

    flu!d KDE Neon 5.16

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    Why not just get it powder coated?
     
  19. Flamin Joe

    Flamin Joe Member

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    I fully understand the desire to get it 100% perfect and original but I think with some things a compromise is perfectly acceptable, especially when the item in question is a flimsy bit of metal which you are not going to see from the outside.

    I have a non working Amiga 500 (as well as a working one) and it too had a fairly badly rusted metal shield. All I ended up doing was treating the rust to remove it then lightly sanding it to smooth out the damage that had been caused. Then I went to Bunnings and grabbed a can of Silver/Aluminium coloured spray paint (I think it was a Rust Guard brand I don't recall I've used up the can since) but basically anything which was the closest match and has rust protection for an added measure. It may not have come out perfect as you can still see where the rust damage occurred as it was pretty bad, but at the end of the day it doesn't change the look of the case from the outside so I was happy with it.
     
  20. OP
    OP
    iMic

    iMic Member

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    That could work. It worked wonders for my IBM XT frame when I had that one done. I'll consider spray painting it as an option as well. I have some cans of etch primer and flat silver around if I need to settle for a working immediate solution.

    And then a last option would be to have entirely new pieces cut from sheet metal, but that's possibly more on the scale of a complete production run, and selling the extras into the community.


    Thankfully I consider the journey half the fun, getting the machine as close to perfect as possible then starting it up when it's back together. Because my last build came together well, I have to consider whether it's worth going as all-out as last time, or leaving it as one of those "good enough" cases to start using the hardware and software sooner. At the moment I'm not pressed for time.

    I'll wait and see what the other metal places say first and decide after that.
     
    Last edited: May 5, 2018

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