Can we save the Amigas for the Museum of Computing?



hello cave-dwellers today is an Amiga 500 rapid repair episode three filthy and broken Amiga 500 how many can we repair this episode is supported by monster joysticks calm level up your Raspberry Pi with our all-in-one arcade kit using genuine Sanwa arcade parts and one click print comm for your photos on canvas acrylic gifts and more local craftsman and global delivery yes it's a meagre time again and you know I hate seeing broken amigas so it's an opportunity to bring three back to life today and they're not just any Amiga 500 these come from the Swindon Museum of computing x' amiga graveyard a corner which I found stacked with these amigas when I went to visit them now the Swindon Museum of computing like many museums is completely volunteer-led so I went there on a Saturday and enjoyed my day out it's a small but extremely friendly museum and I asked what can I do to help the museum and that's when they led me to the amiga graveyard and this site these broken amigas and of course I immediately felt it was my duty to get them repaired and back to the museum so that's I'll go today to look at these machines which are all in different states as you'll see and get them back to this window Museum of computing so that they can exhibit them sell them to raise funds or just stall them until a future exhibition whatever it is they need to do they need them to be working so this is going to be slightly different to a normal episode on my channel it's going to be more of a rapid episode because we've got a lot to get through to repair three machines to look at them to diagnose them and answer the question can we save all of the amigas let's find out amigas is there anything better than a table full of them or yes a table full of working amigas would be a whole lot better so let's see what we can do about that the computers are supplied with no peripherals so I'm using a known good power supply to test them and we'll start by inspecting each machine and deciding how best to approach each one based on the symptoms we find and this is a meagre one it's a revision 5 board with something nasty lurking in the trapdoor expansion slot this is a 512 K memory expansion with a real-time clock battery and a battery which is given up on life and deposited is little battery guts all over the board yes it's nasty but the beauty of the 500 is that the damage is isolated to the expansion card only in very extreme cases does the leakage and resulting corrosion work through the expansion port into the mainboard this is a very different story if you have a 500 plus model in which the battery is on the system board and the results of a leak there can be quite damaging there are no visual problems with the capacitors or unseated chips so I put some power into the board to see what happens and well that's not good we either have a problem with the video circuit and common faults there are two capacitors and two resistors in the area or perhaps it's the custom video chip deniz or something deeper maybe the ROM has failed so these are the areas I think we'll start in with our investigations let's see the condition of amiga number two starting in the tractor again this time we have a much more well-behaved memory and real-time clock expansion card we may well service this and put it back into use but I'll put it to one side for now to simplify troubleshooting this Amiga then is a revision 6a and aside from a little dusty looks ok I'll just have to make sure all the chips are seated correctly and then we'll test it out to see what happens when it comes to testing the machine first signs are a lot more positive than the first Amiga but it isn't all completely well here firstly it fails to read a known good floppy disk so that drive perhaps needs servicing and then I found the keyboard doesn't work the power and drive lights work but no key presses are registered this can be caused by two things either the keyboard itself has failed there's a PCB on the keyboard with the controller which may be at fault all the keyboard membrane may be damaged or perhaps the odd CIA chip on the system board which manages the keyboard has a fault and we can test that by swapping it with the even CIA chip to see if the problem follows it I'm feeling quite positive about this one let's see what Amiga 3 has waiting for us finally a mega number three in the trapdoor here we have what looks like an official Commodore branded memory expansion fancy Commodores 8501 memory expansion was encased in metal shielding and guess what inside we have yet another League in battery and you can see it's been eating away at the board it looks messy but that battery is some distance away from the memory modules and traces there's just the ground plane surrounding it so it may be recoverable today we'll put it to one side and concentrate on the machine but I will snip that battery off and neutralize the leak to try and prevent further damage until I can look at it what we have here is another revision six a board and once again it's a bit dusty but the capacitors aren't bulging and there are no visible signs of leakage and no reason not to test it so let's power it on and first impressions here are very good indeed with the RAM expansion removed it boots up it loads a disc and the keyboard is working is it going to be that easy well it's not to say there won't be further issues so this like the others that we fix will undergo further testing to check it doesn't fall over those are our three amigas and our challenges today so let's see if our diagnoses and attempts to fix them give us any success starting with Amiga 1 which you'll recall has problems with the garbled screen output the beauty of socketed chips is they're so easy to pop out and replace and check if that solves the problem and of course that's what I did with Denise and then the kickstart rom but to no avail here so I approach the problem from the video port backwards and that resulted in a little more work than was necessary but there wasn't such a bad thing the a500 unlike the 600 and 1200 and other amigas does not have a bad reputation for capacitors in fact they're pretty solid and you rarely see them leaking nevertheless I noticed I have the correct caps in stock so I decided it would be prudent to swap these out and test them and also check two resistors which if at fault can cause erratic video problems the makers have quite a large ground plane so to ease removal of the caps I'm using flux and some preheating to warm the area with a hot-air gun I should stop the heat from being too quickly synched away when I'm d solder in the part unsurprisingly for the tough old Amiga 500 there's no sign of leakage on the cap or the board once removed and testing showed they were absolutely fine so this is not our smoking gun our resistors also checked out fine they should both be 4.7 ohms and my multimeter confirmed they checked out so while I didn't find any problems here or Amiga did get too smart new capacitors so working back I replaced a deniz again and this still gives us a problem but a slightly different pattern on the screen but the breakthrough came when I next replaced the kickstart ROM leaving the replaced deniz in place it was the combination of both these chips deniz and the ROM that needed to be replaced to win this a meter over individually those two chips were both broken and needed replacing which resulted in this the old familiar kickstart 1.3 screen and 2 thumbs up from me so we replaced a 40 deniz and kickstart rom and along the way unneccesarily replaced a couple of capacitors new caps are no bad thing this Amiga is now ready for testing or mentor Amiga number two which you recall won't load disks and has a nonworking keyboard funnily enough these problems could be related the a500 has to CIA or complex interface adapter chips and these are labeled odd and even the odd CIA manages the parallel port keyboards and floppy disk functions the joystick and some Mouse functions the even also manages floppy functions as well as the cereal and some parallel port functions if we're having both keyboard and floppy issues then the odd CIA chip which has some overlap for both of these devices may well be the suspect as we have the luxury of some spare parts though why don't we just plug another keyboard in and see what happens and guess what another keyboard works suggesting the original either has a problem with the keyboard controller PCB which is mounted on the keyboard itself or a problem with the membrane and we'll take a look at that shortly because while this replacement works were missing a key and that red power light belongs in a revision five amiga and this Rev six should really have a green power light but antic perhaps but we want it to be accurate for the museum for the disk drive then at first I thought perhaps a little maintenance would sort it out so I stripped it down removed it from the outer casing and gave the whole thing a good clean paying particular attention to the read/write head which needed a good cleanup and also the worm screw here which moves the drive head back and forward and looked like it could use a little grease to keep it operating smoothly so I cleaned off the old grease and applied new grease now I've skimmed through that process quite quickly because not only do we have three amigas to get through but it also well it didn't work on its own but it wasn't in vain the solution was not to service the drive alone which it no doubt needed but it was to also swap out the odd CIA chip as suspected because when we did that things started to behave a lot better with the CIA chip swapped out and the drive serviced our disk reading errors were solved let's round this Amiga off them by fixing the missing key number one is missing from the donor keyboard you may have spotted once inside we can fish out the mangled plunge I don't know what's happened to this this part has a rubber foot with a carbon coating which makes contact with the keyboard membrane below to register key presses this is where keeping old parts around for certainly pays off because I happen to have some spare plungers so I popped a new one in and a new spring and a spare if slightly off-color keycap to complete the keyboard then we added the keyboard controller from its original keyboard and as if by magic we now have a full keyboard which is working and a green power light as it should be as well as that working floppy drive we're using the original keyboard PCB also proves that that worked and the problem on the original keyboard is likely the membrane so I'll order one and then I can replenish my spare parts but for now Amiga 2 is up and working so on the face of it we now have three working amigos to which needed attention and one which possibly just needed that trapdoor RAM expansion removing fingers-crossed that's all it was and here's how I tested them first I ran tear phrases sis test software which is freely available using the link below the video this software lets you test everything in a really simple menu from memory tests and checking all the keys work on the keyboard through to audio video and CIA chip tests it's a really useful tool to have in your amiga arsenal for future troubleshoot him and then to further test the machines and make sure we clocked up a good time on each one and they were fully tested but of course it was time for a bit of gaming some turrican – here I played and then I fired each one up on Twitch extended testing turned out to be great fun I really enjoyed spending time with you guys testing out the amigas and we got to revisit some old classics but it wasn't completely problem free Amiga one we found had problems with the mouse and later when I moved the disc drive out of the way well it was quite obvious why this resistor our 401 was scorched and after a quick swap out my mouse port was working again an Amiga three the one we simply took the RAM out of the expansion slot on well that did have some surprises for us an occasional guru error on cold boot although it did work fine after the error and after a bit of head scratching eventually we replaced the kickstart ROM and it has been behaving for me ever since all that remains is to wipe them down load up the car and take them back to the museum where they can decide if they want to refurbish them to exhibition standards whether they want to retro write them I don't know what the museum stance is on retro writing whether they favor it or disapprove of it that's their decision to make today it was purely a technical video to get the machines back up and running so if you're ever in the area do check out the Swindon Museum of computing there's lots of hidden gems there it's a small but really friendly museum the volunteers are great to chat to there who knows maybe you'll see one of our amigas on display and you can enjoy it rather than it festering in a corner in the Amiga graveyard as always thank you for watching thank you to the museum for letting me work on these and to all those volunteers who make the museum possible I really did enjoy when I came to visit and no doubt I'll be visiting lots more in the future thanks everyone take care see you next time if you enjoy my content and would like to toss a coin into the hat to support the cave then check out patreon.com/crashcourse as you can see on the screen now thank you for your support

34 Comments

  1. RetroManCave said:

    Museum of Computing : https://museumofcomputing.org.uk
    This was an intense episode to make but great fun. Thank you to those who joined me on https://twitch.tv/theretromancave for the live streaming. I'm happy with how the repairs went. The final fix on Amiga 3, swapping out the Kickstart, is one I'll continue to monitor to make sure the Guru's don't return. If they do it might be time for a recap if slight power problems are affecting Kickstart at boot time, but fingers crossed it's all good now. I'll share some pictures with you when we return these to the museum. Thanks for watching – Neil – RMC

    May 23, 2019
    Reply
  2. Retro Storm said:

    Sometimes heroes wear gloves instead of capes.

    May 23, 2019
    Reply
  3. Neb6 said:

    Here are some photos of a NOS Amiga 500 that was recently unboxed (for those who want free and high-rez images of a mint machine for whatever purpose):
    http://www.blitter.com/~nebulous/AmigaPhotos.html

    May 23, 2019
    Reply
  4. smakfu said:

    It’s not just great to see these machines fixed, it’s also very helpful to see demonstrated diagnostic fixes for those of us who are keeping these old machines working.

    May 23, 2019
    Reply
  5. oskar20086 said:

    Beautyfull machines, Greetings from Venezuela

    May 23, 2019
    Reply
  6. silver button without video said:

    Terry davis brought me here

    May 23, 2019
    Reply
  7. empire of the rising zucc said:

    watching you repair several amigas in a row is my asmr

    May 23, 2019
    Reply
  8. Retrojunk Review said:

    brilliant video Neil, love amiga 500's

    May 23, 2019
    Reply
  9. Ralf R. said:

    Great Video!!

    May 23, 2019
    Reply
  10. IkarusKommt said:

    Are they going to pay you for the spare parts?

    Also, LOL @ that ISO keyboard with two blank keys.

    May 23, 2019
    Reply
  11. Jerker Ivarsson said:

    great, as usual dude:-)

    May 23, 2019
    Reply
  12. Alistair Brugsch said:

    Glad to see someone as particular about red/green vs green/yellow lights as myself. I love my rev 5's lights, down to how they actually go out when flashing rather than just dimming.

    May 23, 2019
    Reply
  13. ditroia said:

    Your my hero.

    May 23, 2019
    Reply
  14. 10 Minute Amiga Retro Cast said:

    Great that they all came back to life! It is so helpful to have spare parts available to test these.

    May 23, 2019
    Reply
  15. Madd the Sane said:

    13:54 Cool, they have an Apple ///!

    May 23, 2019
    Reply
  16. Gerard Kean said:

    It's too bad that museum is on the other side of the world. all there is by me is https://www.motat.org.nz/ with a small section on old computers, 8bit and backwards

    May 23, 2019
    Reply
  17. MultiMidden said:

    Wow I donated my old A500+ to them a good 10-15 years ago. It was certainly before either the Bletchley Park or Cambridge museums opened.

    May 23, 2019
    Reply
  18. me0262 said:

    1:38 They should all be like what I rename my Trash / Recycle Bin: Amiga.
    Kidding aside, awesome that you got them working. Shame those batteries leak all over the place.
    #OldWarsAreOverButNeverForgotten

    May 23, 2019
    Reply
  19. Tomi Antenna said:

    We sure can! I kept my original Amiga 500 that shipped with Kickstart 1.3 and Workbench (I still have disc!). I got on christmas in 1988, and it literally changed me, had a fundamental impact on my life. It saddens me to say that not all the original parts survived the journey. And it also saddens me to say that I kept a few hundred assorted floppies with random pirated games and junk on them too, and that I'm about to turn 40. Amiga 4 lYfE! Shout out to ONSLAUGHT! TRILOGY! RED SECTOR! TRISTAR! THRUST! DEFJAM! CASCADE! QUARTEX! PLUSH! Legends then, legends now, never forget.

    May 23, 2019
    Reply
  20. You don't need to see his identification said:

    Damn, I wish I were wealthy enough to have an Amiga habit 🙂 (And intelligent enough to program for them! 🙂

    May 23, 2019
    Reply
  21. Derek Cameron said:

    the amiga 500 still looks classy even today!

    May 23, 2019
    Reply
  22. Jawolf said:

    Great to see you fixed the Amiga 500’s! I was looking n Swindon last week visiting a friend. I will try and visit next time I am there.
    I also help out at the Retro Computer Museum at Leicester. All our computers are playable so come and visit.

    May 23, 2019
    Reply
  23. Andy W said:

    Great video.. really enjoyed it. Good to see the Amiga's being rescued and repaired. 🙂

    May 23, 2019
    Reply
  24. Charlie Cat said:

    You're welcome kind sir. Always a pleasure seeing what you do best. 8^)

    Also I contacted you on Twitter right now as well. Maybe you like to join in on this bro. 8^)

    May 23, 2019
    Reply
  25. Charlie Cat said:

    WOW. Just WOW Neil.I'm just lost for words on this great video kind sir. 8^)

    Anthony..

    May 23, 2019
    Reply
  26. Dave Bradley said:

    I have recently been going through some of my own Amiga 500's…7 of them as it happens…and to start several of them did not work, but after patiently going through them all, I have all of them working, I am only short one floppy disk drive…only an Amiga 2000 that had battery corrosion issues died but became an organ donor to help save the 500's!

    May 23, 2019
    Reply
  27. crapcbm said:

    send them to me 😀

    May 23, 2019
    Reply
  28. Adam said:

    Doing God's work

    May 23, 2019
    Reply
  29. Jérémie Faucher-Goulet said:

    Music at 1:35 sounds a lot like a "I gotta a feeling" from the Black Eyed Peas. Unless I'm mistaken?
    In any case, it sounds epic and perfect for that part of the video.

    May 23, 2019
    Reply
  30. Petrus Perius said:

    Reminds me that i should repair my old stash. Got 2xA500, 2xA1200 in pices and only one working floppy drive between em all.
    At least the C-128D is working.

    May 23, 2019
    Reply
  31. reggiep75 said:

    Nice work and glad to see some classic tech back in action to be enjoyed by us who were around when it launched and kids today who can see many aspects of retro computing.

    May 23, 2019
    Reply
  32. qettyz said:

    I could take a tip here. I have rev 6 amiga 500. I have changed all the caps, but still flickering (like every second or two) screen until it warms up. Flickering gaps grow longer while its warming until gone. About 2-5mins flickering from cold start.

    May 23, 2019
    Reply
  33. FRIENDLY JAPANESE BUSINESSMAN said:

    <3 amiger

    May 23, 2019
    Reply
  34. Ian Jeffery said:

    Hi, great video. Quick question though – what would cause a fault in one of the chips that requires it to be replaced? Ian.

    May 23, 2019
    Reply

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