Amiga 500 Restoration

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

  1. OP
    OP
    iMic

    iMic Member

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    It appears we have success; a Silver Zinc coating is possible for the RF shields, and Gold Zinc for the drive bracket. With the chemical surface rust removal, the estimated price is about $100.

    A little more expensive than paint, but considering cost of materials, time and labour - not by much, and for hopefully a much better and more durable finish.

    It'll take around 2-3 weeks to complete as a low-priority job (which presumably keeps the cost down), but I'm in no rush.
     
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  2. badmofo

    badmofo Member

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    You can't buy much for a 100 bucks these days, I reckon that's OK for a job well done. Looking forward to seeing the result.
     
  3. OP
    OP
    iMic

    iMic Member

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    That was my thinking. I'd heard some instances of Amiga fans on YouTube being quoted 500 GBP (875 AUD) for a professional plating, so go the local businesses. If it comes back in good shape, I'll pass their details on to some of the local and interstate groups in case anyone else with a rusty machine wants to have theirs repaired.

    ---

    I'm now grappling with a difficult motherboard situation.

    The 6A board has some corrosion damage. I've attempted to repair it by polishing out the rust and corrosion, but some parts of the gold left-side expansion contacts are just gone. There's some corrosion around the trapdoor expansion connector as well. It powers on and runs, so the chips are good, but the board is rough.

    I mentioned a donor board, which I still have, but it's a much earlier revision than this machine was built with, and it needs some work itself.

    I was bidding on some replacement Rev. 6A boards on eBay, but lost both of them in the last few seconds.

    So I need to source a replacement Rev. 6A Amiga 500 board to continue the restoration. Whether it's missing its chips or not doesn't matter.
     
    Last edited: Dec 10, 2018
  4. Flamin Joe

    Flamin Joe Member

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  5. OP
    OP
    iMic

    iMic Member

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  6. OP
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    iMic

    iMic Member

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    So I bought another one.

    [​IMG]

    My workspace needs to be reorganised, and needs better lighting. So many projects, not enough time.

    This machine is a Rev. 5. The motherboard is in good condition, the shields aren't too bad, and it has a 512KB RAM expansion with some corrosion, but it works and should be repairable. The machine works, it's reasonably clean, and it only needs minor attention in a couple of places.

    It's connected to the PVM via Monochrome Composite for now. Still better than an A520 RF modulator, even without colour.

    The Rev. 6A machine is still repairable. I'll finish fixing that board and reassemble it into a complete machine soon, and then chances are I'll sell it to recover some of the costs.

    As for the spare Rev. 5 board and keyboard, I'll either assemble those in a replacement case and expand them with aftermarket upgrades later, or simply keep them as spares for this one.
     
    Last edited: Nov 24, 2018
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  7. OP
    OP
    iMic

    iMic Member

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    Slowly coming along.

    I exchanged the shields currently in at the electroplaters with a better set, so we're starting with a better foundation. Hopefully the current set, with less rust, will result in a much better quality finish when the Silver Zinc is applied.

    An exciting development as well, I have a replacement motherboard coming across from the UK. A revision 6A, 91/92 production on a dark green PCB.

    I noticed my current board is an 89/90 production on a green and gold board, but the differences are only cosmetic. Still, assuming I'm being incredibly pedantic and choose to find a production year and colour matched board, that board would do brilliantly in a new production replacement shell, with the Mitsumi keyboard, some replacement keycaps, and an aftermarket accelerator to build a seriously fast A500.

    Chances are there will be some spare parts available after, particularly some Rev. 5 motherboards, and in excellent condition too. Within the next few weeks or months, as these machines and parts start nearing completion, I'll likely gather whatever I have remaining and offer it up to the community.
     
  8. OP
    OP
    iMic

    iMic Member

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    And another motherboard is on its way. A revision 6A of 89/90 production on a green and gold PCB. I'll need to assess the condition of this one, but it looks promising from the pictures and it's a much closer match to the existing board. (Even the serial number ranges are close.)

    I'm interested to hear from everyone. What are some must-have upgrades and accessories for the A500? Some that come to mind:

    Then there are possible expansions for the second Amiga, provided I can afford to build it:

    But that machine wouldn't be built for quite some time, or at least not all at once.

    Of course even the first round of accessories and upgrades requires cash. So on to repairing the second machine in preparation for resale. It doesn't need much, the motherboard is fantastic, the case is good, and the keyboard works. It's just the shielding that needs attention.

    On with the paper, soaked in rust remover:

    [​IMG]

    They'll need a light sanding once that's done, then a light polish, then back into the rust sealer to protect the metal. It won't look brand new, but even so, it'll still be quite good.

    The RAM expansion needs some attention as well. Battery corrosion as usual, so I'll need to clean that up, replace some components and maybe run some jumper wires depending on how the board traces come up.
     
  9. DonutKing

    DonutKing Member

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    A Gotek floppy emulator with HxC firmware (and optionally a DF0 selector if you don't want to modify the motherboard, or don't expect to ever use floppies) plus a 512KB trapdoor expansion will let you run the vast majority of Amiga ECS software.

    While you could put an accelerator on it, it's a rabbit hole of money and I'd suggest this is better matched with an AGA Amiga.

    I had an A500 with ACA500 and 68030 accelerator but after the novelty wore off, I sold it and got a Gotek with HxC firmware, and have been quite happy with it. In fact in some cases where the Chipram bandwidth is being fully utilized, adding an accelerator will actually reduce performance compared to a stock A500.
     
  10. OP
    OP
    iMic

    iMic Member

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    The original machine must be configurable back to stock, so a DF0 selector is needed in that case. The Gotek will be connected externally. It already has a 512KB trapdoor expansion (a HE500) so that's taken care of.


    This has me thinking. I haven't established any reason why I'm interested in doing this at all yet.

    The original A500 restoration makes some sense, it's an incomplete project I was given and I want to see it through to completion. Maybe even run some software on it afterward. But I'm not exactly interested in games, outside of a few. I'm interested in chip music and connecting old machines to the internet, something my 386 machine already does, but honestly in comparison I don't find the 386 all that interesting.

    The expanded A500 is almost an exercise in absurdity. There's little reason I want to build it outside of having a ridiculously powerful and obscure computer to use as I see fit. I suspect it's because it's a completely open and uninhibited architecture. (I worked for Apple, I know what locked down hardware is like, and I've come to hate it.) Not the most powerful computer, but one of the most versatile for someone interested in electronics, except for perhaps a Raspberry Pi (or Arduino in specialist applications). To me, that Amiga would be a terminal to control other machines and electronics, connect to text-based online services, something to play music on, and perhaps the occasional game. But mostly, the fun would come from building it. It doesn't serve a strictly practical purpose otherwise.

    I'd rather build an A600 or A1200, but both are difficult to find and too expensive when one does come up. I discovered that in some cases it would actually be cheaper to order the individual components and build an A1200 than purchase one outright. A500s are relatively accessible in comparison. Two of the three machines I have were free or traded, and all three were sourced locally. (Or at least within Australia.)

    Apparently the Vampire 500 has a SAGA core either already available or in development that extends the A500 with an AGA compatible chipset, implemented on the FPGA. I think. I haven't looked into it that much. The Vampire accelerators are expensive, but (combined with a free A500) it's still cheaper, faster and easier to find than an A1200, and it comes with 128MB RAM, IDE drive and HDMI video support.

    But ultimately, who knows if it'll actually be worth it. It may never be used. I could build it, shelve it and never use it again, and at this stage I can't be sure. So I'll build the standard A500, attend some Amiga user groups, get some feedback and decide whether (and how) I'd like to proceed from there.
     
    Last edited: Dec 3, 2018
  11. Flamin Joe

    Flamin Joe Member

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    With any system I've obtained/repaired my philosophy has been to keep everything original and only rely on modern improvents such as Gotek, XT IDE etc if necessary.

    In the case of my A500, I haven't even cracked open the case and all the security seals are intact. As tempted as I am to install a Gotek I just can't bring myself to do it. I enjoy using the limited collection of original floppies I have and every once in a while hunting down another game to enjoy. In a way it's much like it use to be where I had to make do with what I had. If I had a Gotek i'd be spoilt for choice and would probably find myself jumping from game to game never really spending much time on one.

    Just my 2 cents. :)
     
  12. flu!d

    flu!d Ubuntu Mate 16.04 LTS

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    Actually, running an ACA500 and an ACA1232 my A500 was a very capable machine. With a fully functional AmigaOS 3.1 workbench and WHDload I was able to play any game/demo you could think of and the machine was internally untouched.

    Yes, the A1200 is a better machine, but it's also far pricier.
     
  13. OP
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    iMic

    iMic Member

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    I have a similar philosophy. I like keeping the original components in place, with exceptions for upgrades that were available when the machine was built, like RAM expansions and disk drives.

    I'd prefer to use physical disks with my A500, but it seems that a good deal of them are degrading, so while a handful are readable, a bunch of others aren't. Having an externally connected Gotek seems like a reasonable compromise. I don't need to hack up the machine, the DF0 switch installation is reversible, and since it keeps the original disk drive in place, and I can always write new disks as well. I'll need to open the machine to install the DF0 selector, but the machine was already disassembled when it came to me, so any sense of keeping it completely original was already gone long ago.

    Building a second machine for tweaking is mainly because I have a surplus of spare parts from my broken-cased A500. It was already broken, so I suppose I don't have to feel guilty about it. That and the replacement parts it needs - a case and keycaps - are available as new production parts. The idea of expanding it snowballed from there, something like "if I'm swapping X, why not do Y as well". There's no real reason I'd want to build it, other than interest and curiosity, but then that's the main purpose of using and maintaining old computers, I suppose.
     
    Last edited: Dec 3, 2018
  14. power

    power Member

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    I have Schrodinger's floppies, if I never take them out of the box anymore they are both working and not working!?

    when i gotek my A500 it's going to be internal I'd say the FDD does not work anymore afaik.

    I thought about buying a new one but haven't gotten around to it yet, I might even go external as I have a DF1 that I can cannibalise for a working floppy. So it'd all even out.
     
  15. OP
    OP
    iMic

    iMic Member

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    The test pieces came back from the platers.

    [​IMG] [​IMG] [​IMG]
    [​IMG] [​IMG] [​IMG]

    They're certainly better, but I wouldn't say perfect. Some thoughts -

    • All pieces need to be sanded to 2000 grit to level any high or low spots before plating. The chemical solution can only so much.
    • The bottom piece came up much nicer than the top, perhaps because it's a bit more rigid.
    • The gold finish on the Floppy cover looks really nice in person, but like the others, it needs to be sanded and levelled first.
    • I like the Zinc finish in terms of colour. If the pieces were better prepared, the matte finish silver and gold would be quite a nice look.
    • It may be possible to polish and sand some of the spots to improve it, but as the coating is only 12 microns thick, it could damage the finish. There's no way to tell without trying it and being prepared to ruin it.
    • The bottom piece may be usable in the custom machine, since the top panel would probably be left off to accomodate some expansions and accelerators anyway.

    Would I pursue this as an option? Perhaps. I'd need to sand and level another spare set and retry it to see if we can improve the surface finish. If it's possible to do, then it'll be quite a nice finishing feature for the A500.

    If not, then I probably wouldn't. The Zinc is much more rust resistant than the stock shielding, but in terms of appearance it isn't necessarily better, just different. To justify the expense I would need to see a noticeable improvement in appearance over leaving it as-is.

    And the platers that did the work did an excellent job, given the condition I delivered this set to them in, and they're working with me to improve the appearance of the next set, should I choose to continue.

    So from here, I'm awaiting the replacement motherboards. Those boards come with shields as well, so depending on the condition of those, I may choose to leave them as-is and be done with it. Otherwise I can always prepare another set, sand out the imperfections and try for another round.
     
  16. OP
    OP
    iMic

    iMic Member

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    The first replacement motherboard turned up, and it's near perfect. It needs maybe a cleaning, but there isn't a hint of corrosion or tarnishing anywhere. That board is ready for installation into the restored machine, once I choose a bottom shield to fit it into.

    Time for another experiment, this time to restore the shielding on a budget. This set is really rough, the metal is tarnished in a wrinkle-finish, and it needed a decent amount of sanding to smooth out the surface.

    [​IMG]


    I don't particularly want to spend a lot on this set. So I decided to try an Aerosol Zinc coating. I went with Dy-Mark Zinc Guard Silver Bright, around $15 from Mitre 10. There are possibly some better options, like Dy-Mark Silver Zinc, which is a dual action primer and coating.

    [​IMG]


    A quick sanding with 2000 grit to smooth out the surface and remove any rust, then a wipe down with wax and grease remover, before a few quick coats of zinc.

    [​IMG]


    And it doesn't look half bad. I still need to give it a few more coats, then test to see how well the surface finish holds up, but if it all works out this could be a good option for anyone wanting to clean up their Amiga for relatively little cost.
     
    Last edited: Dec 10, 2018
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  17. flu!d

    flu!d Ubuntu Mate 16.04 LTS

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    Actually, I must say that I agree with this. The A500 benefits from a faster processor, until software hits the chipset directly - Like certain games and demo's, then the A500 actually runs slower with a faster processor.

    The reason is the A1000, A500, A2000 all have a 16 bit bus, interfacing a 32 bit accelerator with a 16bit bus creates bottlenecks. Running an A1200, A4000 with the 32 bit bus this is by no means an issue when running a faster processor.

    The exception is the Vampire series of accelerators, as they recreate the entire custom chipset in FPGA.
     
  18. OP
    OP
    iMic

    iMic Member

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    After around 6 hours.

    [​IMG]
    [​IMG]


    I'll let them dry into tomorrow. But they sure do look good at the moment.
     
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  19. OP
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    iMic

    iMic Member

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    I finished one of the Amigas earlier tonight. Photos inbound.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    I'm confident that this machine is the one I'll sell. It's in great condition with only minor wearing, no rust, the board is mint and the drive works. But when completed my other A500 will be in ever so slightly better condition, and I have the original packaging for it.


    The HE500 Memory Expansion board needs some work though. It isn't detected by the system, and the battery corrosion has broken some connections across a few tracks. I think it's repairable though. I'll look into fixing it when and if I find some free time coming up.

    [​IMG]

    [​IMG]
     
    Last edited: Dec 12, 2018
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  20. pelmen

    pelmen Member

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    Sort of but for V3.0 to V1.x they are backwards compatible at least. So you can run lower workbench version on higher kickstarter. V1.2 and 1.3 WB and KS were compatible in all variations. But V2.x onwards introduced much that required the appropriate KS chip for the libraries to load. Actually i think thats the cut over point, pretty sure WB2 & 3 runs on KS2 but not KS1 though it might boot to the workbench and maybe some stuff can run.

    A kickstart switcher is a good upgrade with a 1.3 and 2.04 chip on it. And that will cover all workbenches to V3.x from memory.
    I know you dont want to cut holes etc, but the amiga is so robust for hardware hacking. Early on I had a heap of soldered in hacks and stuff all wired to DB25 socket on the back, I had about 2m of ribbon cable from that to a hobby box in the draw of my desk covered in toggle switches to configure how I wanted. If someone stole the amiga it wouldn't have worked without my secret box. Anyway many mods ended up plug in boards with a toggle switch at the end of a foot of cabling, easy to cut and solder etc of course. I suggest you look for a replacement sidecar panel on ebay for your case, that can be somewhere you can drill/cut to attach switches for the mods and keep original cover safe and clean. Dead easy then to return to stock condition at any time since chips are socketed so the plugin mod boards are no problem on that score.

    And yes you can stack boards too, my A500 has an ATOnce286 board plugged into the 68000 CPU socket, plus a 14MHz 68000 accelerator plugged on top of that all inside the case. eventually i did away with the toggle switch box and installed a row of switches in the case just across the top of the keyboard. Neatly labelled with those rub on lettering stencils from craft stores. the whole thing painted satin black with "stealth" painted in gloss black across the bottom of keyboard. sexy and long before the Web or "case modding" existed. Any old soldering iron was fine to work on them and chips were easy to understand, plus you had BASIC so you could explore your hardware and software nerdness at the time. These days you can only do that with arduino and pi, plus you still need another computer so really you cant even use those.The Amiga had it all there in one box, no extra crap to buy or connect to it. Plus it worked! So it was fun to use and learn with. Still got those John Laws tapes that came with my first one :)
     

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