I need to follow my own advice with this Amiga 500
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- čas přidán 8. 09. 2024
- #commodore #amiga
It's time for anote Amiga repair video. This time we have an Amiga 500 that presents as "dead" with just a black screen. Let's get this fixed! Bonus content of testing a RocTech RocHard external RAM+Hard drive expansion unit.
--- Info
Commodore Amiga 500 Rev 5
RocTecn RocHard 800C
--- Video Links
Amiga 500 Rev 5 fix and ROM upgrade:
• Corroded Amiga 500 Rev...
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Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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--- Instructional videos
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I worked in an Amiga store in the 90's. The very first thing we ever did to fix Amigas was to simply reseat all the chips before any other troubleshooting. That fixed them a lot of the time.
Absolutely. However that Agnus socket was always very tricky to work on. Especially if you had that brittle dark brown colored socket.
I was about to post the same thing, turn on without doing anything, then disconnect non essentials like the floppy completely. Still not working? Reseat all the socketed chips. Only then start testing other things.
BTW, if you think measuring on the wrong CPU pin is embarrassing... I once spent 6-7 hours working on a customer PC that seemed to power on and boot up fine, but the monitor screen was black. Power LED on the monitor was on... Hm. Turned out I had 2 monitors on the desk and I had hooked up the wrong cable. The PC worked fine lol. I replaced every single component in that thing... not my brightest (long) moment.
I bought a Rev 5 Amiga 500 from eBay that was non-functioning. I popped the chips out and gave the sockets a clean with contact cleaner, and then the machine fired right up. Not sure if the A500 sockets are extra prone to corrosion or what, but since then I try reseating the chips with anything that has sockets.
I also worked at a Commodore/Atari store as a repair technician back then and I concur. PLCC sockets in particular were a terrible idea and the source of SO many problems. They were extremely frustrating to deal with, especially the fragile ones Commodore used.
I started in PC repair in the early 90s but I had a few friends with Amigas to know that reseating chips comes right after checking the PSU. Then go call someone who knew more than me. :)
You have reached the highest state of existence, Adrian. The Computers just capitulate and fix themselves when you touch them.
I call that, the Fonzie Move... Iol
Nahh, that's an aura. Certain ppl, if called to troubled workstations, just lay their hand on the wireless mouse, and suddenly there IS NO PROBLEM! I witnessed and still witness this once a week. It's magical, it's wonderous, it is baffling but it is almost a repeatable effect... beyond phenomenon.
@@bloeckmoep Doesn't work for me yet, I need to pray more to the Omnissiah.
@@bloeckmoep It is very handy though haha
and agreed lol
@@BenCos2018 It is handy, but it makes everyone else look like a dumb brick. Found myself numerous times dumbed down, now if any problem arises on the workstation I sit, smartphone out, camera on, record. Wait for magic hands to appear, show video, ask if any step was wrong or incorrect...! Let magic hands repeat successfully.
You'd be shocked to know how many Amigas jump back to life after simply reseating all of the chips. That's all it needed.
Yeah, and I can't count the number of times I ran into non working x86 machines, not booting, simply because the ram needed reseating... So, it's not surprising from a machine that's 15 years older than that ...
I have to reseat all the chips in my A1200 to get it to work!
Adrian, even with the 'self-healing' machines, you're still demonstrating how to logically troubleshoot the device in front of you, with the proper test equipment. In my opinion, that is still educating & entertaining. Please keep up the good work. Each video is a learning experience. :)
bad tin sockets cause weird problems
I beg to differ. My logic for an educational video would be start by removing the floppy drive, remove the socketed chips, clean the connector, and only then switch the system on. With that configuration I would start checking the 5V and 12V lines, clock lines, reset lines, etc, etc, to make sure that I know the basic state of the machine.
Only when I had checked out the basics would I start populating the sockets, one chip at the time, rechecking the result. It might be a boring way to do stuff, but that I how I debug stuff. Start with the known basics, and then add complexity.
Maybe it is the universe giving you a break since those TRS-80's caused you so much grief. Serious this proves to people like me if you don't have test equipment like me remove everything that isn't needed and re-seat the chips.
That's what I was going to comment
On similar but typesetting equipment I used to go at ICs and connectors first with an eraser back of pencil. With owners waiting while down the drain money is bleeding, this quick and dirty (but lucky) first move is astonishing 😂. Better odds than reseat all ICs method. Awesome story! Scratched my head, too!
Just a note: in M68000 the #HALT pin is an open drain, therefore if you disconnect the pin and measure it you may read 0V even if the signal is not asserted, as it would be floating. You need to connect it to a pullup.
On the other hand, if you check that signal on the board, it's got the pull-up, so you actually can see whether or not it was getting an external halt by taking that pin out.
Just came in to explain 3-state logic, beat me to it. I was screaming at the screen while watching.
@@8bitwiz_ Yeah, what Adrian should have done was to check that pin on the socket without the CPU in. With the pull up there, it had to be HIGH.
I was telling him also, but he couldn’t hear me. He even showed the pullup on the schematic.
Even very clean looking chips and sockets can develop a bad connection over time. I'd guess that even the tiniest amount of molecular level oxidation or metal interaction can be an issue at 5V. Reseating chips fixes a surprising amount of faults on old equipment.
You broke your own rule; Deoxit that socket!!! :P
Everything may look fine, and be clean and shiny, but if you looked up close with a microscope there'd probably be signs of oxidisation on the contacts & pins on the ICs, which caused the issues, and this can happen from just atmospheric moisture getting in, so, reaseating the ICs breaks that up and makes things work, causing the self-healing... :)
Good name 👍
Exactly. That green mold he cleaned off of the expansion slot pins should have been the first clue that oxidation took place on the socketed chips.
I used to work for a Commodore Dealer in the late 80's - The Agnus was a common fault and to fix it we would drop the Amiga from a couple of inched on to a desk. Worked more times than it didn't!
exactly! customers were only slightly alarmed by this XD
So kinda like beating an old crt tv until you got a clear picture or blowing into a cartridge to clear the dust out. That’s such a weird fault that doing that manages to fix it.
Pretty sure the same procedure was in the official Apple ][ service manual ;)
@@SomeMorganSomewhere it was the recommended way of fixing the notoriously faulty Apple III
I worked for a minicomputer company in the 80s. Occasionally I’d go work in the repair center fixing boards. For certain ones we’d throw them to the static mat on the floor (flat) to reseat chips or, in some cases, the tops would pop off of the bad chips due to having overheated, which we’d then remove and replace. These were big boards. 15x15 inches square or so. Fun times.
I always try reseating socketed chips. I know you do too but this trouble shooting you did is what makes the videos interesting and fun to watch.
I wonder, what is more relible? IC vs socket.
It was the sockets. You simply cleaned up very minor contact issues. I had to re-seat and clean up chips on all my Atari ST's after they sat for years. Fixed everything on all 3 units. A lesson well learned and well taught.
Yep. The last place I worked at has a mobile lab to go out and test smoke stacks and all their equipment gets minute amounts of debris and corrosion from exposure. Reseating the chips helps to remove the corrosion.
I got them to buy a bunch of micro mesh pads and q tips so we could polish the contacts. They have to reseat the chips a lot less often now.
Edit: and by corrosion I mean literal corrosion as well as whatever junk is in the atmosphere around the stacks coating stuff as well.
Think this illustrates one of the reasons why so many manufacturers switched to just having stuff soldered on directly to the board instead of putting in sockets - as much as they may make stuff easier to repair, they often come with extra reliability issues. 'Tis also why I would generally reseat everything first thing if such a machine wasn't working.
depends on the sockets, 'double wipe' types rarely have issues unless its had wires or a pin header rammed in them, that can stretch the contacts , some say 'turned pin' ones are better but i've also read they can be similarly damaged, usually when a previously soldered chip is rammed in unless you get all the solder off first
Solder in board and inside BGAs also crack, and capacitors get leaky/dry you know. In socket's case you just have to mechanically refit them. Now try to "refit" a BGA chip.... No, you can't.
That's without counting these days manufacturers aren't applying a proper conformal layer on their boards, starting with Samsung and Apple, so these things rust now even on very minimal moisture.
Nice try to defend non repairable electronics, but such argument will not fly too far.
i always at least 'reseat' socketed chips, and sometimes remove,wipe with contact cleaner, the refit, as i've had a few issues with bad contacts, had a spectrum 128 that would crash if you barely touched it until i did the above!
@@hyoenmadan Not trying to defend non-repairable electronics. Far from it. Today's planned obsolescence tactics are horrible and shameful.
I have no idea what solder cracking or capacitors drying have anything to do with this argument, though - the sockets themselves are soldered in as well, and thus would suffer from the exact same problem - you just now have two failure points instead of just one.
And if a chip fails, well - back in the day, an average user wouldn't try fixing a computer on their own. Not like you could just go to a corner store and buy a loose SID for your C64. They'd either send it in for warranty, or give it to a repair shop. Those places would have the equipment to replace these soldered-in chips easily, at least when it comes to through-hole stuff.
You know these computers like the PET, Commodore 64, Amiga, and so forth remind me of the original classic cars.
They were never designed to last much more than 10 years. But through passion and perseverance people continue to keep these things going.
Amazing.
And this is about a minute into the video so I have no idea if he truly does fix it.
agreed
I bought 2 dead amigas last week... both working great... after 40 years... they survive... and the ic of the amiga could live 100... :D even the caps are allways ok even after 40 years...
they had several cables not connected and some doing weird stuff like the inverted floppy connector... hahaha I was amazed when the floppy hand appeared on both computers bougth them cheap
Adrian, you are running into the same situation as we did in aircraft maintenance in the Air Force. Old avionics equipment often began working again with a card reseat. So when fixing a nav computer say, the fix may often be “Reseated computer. Op check good”. 😊
I’d love to see that come up more in military dramas lol. Did you ever have a CO in disbelief at how quick you fixed them, or were they clued-in enough?
When we were notified of a problem we start talking about what it could be. Sometimes we would pull a piece of equipment out to check for broken wires behind the mount. After reinstalling the box and it starting working all you can do is sign it off as a reseat of whatever box. 😊
FYI when you pulled out the HALT pin, its an open drain output, and would always show up as 0V unless you put an external pullup resistor on your scope probe.
I thought the very same thing
Not only that, but in monitoring A1 or A2, we have to remember the first address is 0 and we're ripping things out so we have no idea what the CPU picked up to do next. Granted the 2nd fetch on start is address 4 so A2 should be seen at logic 1 briefly.
@@danman32 the 68000 does two longword fetches from $0 and $4 to start with - these give it the initial stack and program counter. In the Amiga, the ROM has an overlay setting which ensures it is seen at location $0 (normally it is $F80000) to get these two vectors.
@@jaycee1980 I heard what Adrian said which you're just repeating. You missed my point.
My point is that the address lines monitored joule very well be legitimately low with the testing being done, particularly when the startup starts them low.
Maybe you'll catch A2 high when it does it's 2nd vector fetch, but after that, you don't know, especially when you took the circuit apart.
@@danman32 well yes if you want to see whats going on at the cycle level you cant just scope out the address pins - you need to follow the whole cycle with !AS etc
As others have commented, HLT and often any asynchronous bidirectional control signal is likely to be open drain and needs to have a pullup resistor. You cant leave those connections floating. I'm not an expert by any means, but I was almost screaming at my screen when you left HLT floating 🙂and knew that would send you down a rabbit hole. When you are looking at a 68000 other pins to look at for activity are AS and DTACK as they control the bus cycle. The 68k bus works very different than a 6502. Good video Adrian it is nice you put out the videos where everything goes perfect along with those that don't. Those can be just as instructive. Keep it up!
You can at least lift HLT from the CPU to determine who is holding HLT low - Gary or the CPU. If it's the CPU then its usually the sign of a bus conflict - and you start looking for things like enable pins being floating or low when they shouldnt be. This is very common on a 500+ that has Varta damage
Agreed, DTACK must be looked at. Unlike the 6502 and the Z80, the 68000 has an asynchronous bus. Instead of holding up the CPU with /WAIT as for the Z80, the chipset has to acknowledge that a bus cycle can proceed using DTACK. If that does not happen, you can look confused at the system for hours. Ask me how I know...
@@michaelhaardt5988 !DTACK is another one that often goes bad on Varta'd 500+'s - one of the first things i check on a black screen machine!
As Adrian was playing with the address pins, I was thinking: Check DTACK. If it isn't low, nothing else matters.
Of course he wouldn't know that from working with 6502s.
36:14 What have we learned here? De-ox it that socket!
As always another brilliant video.
I always make a comment to wife if she's about when I’m watching these videos from Adrian that he's the happiest youtuber in the world!
Look carefully on the Quantum hard drive label - it will detail the amount of power that it needs and it needs quite a bit. Also, 8mb of DRAM used to use quite a bit of power to refresh.
Those scsi drives are quite power hungry
I said this before. I can't say how many times that just cleaning pins fixed early computers. Oxidation on connectors was a real problem back in the day.
Still great troubleshooting info in this video! Great to see your process as you consult the datasheet and breakdown the steps of the system booting.
If the contacts of the socket and chip are of different metal alloy, galvanic action takes place using the humidity in the air, and will corrode the contact area.
The corrosion is a salt that doesn't conduct. When you removed the IC from its socket, it was hard to break through the corrosion and that's why the IC felt secure in place.
Once you removed the old chip and inserted a new one, the socket developed new scratches on its pins and your problem was over.
I always removed ICs from their socket and reinstalled them to make sure the contacts were fresh.
Ha. Its got to be some kind of metal reaction between socket contacts and chip pins. Oxide build up or whatever. Even though the board looks very clean, that reaction must be taking place maybe microscopically. I guess your 'deoxit that socket' mantra needs following with these self healing machines!. Great video. Thanks.
Adrian your videos are a balm for my soul some days. Thank you so much.
When I was a kid I've repaired my ZX Spectrum clone just by putting some pressure on IC chips, and it worked. I thought my speccy is done and requires professional repairs, I couldn't be more happier to have it working again %)
A common issue with Atari STs. The PLCC sockets would get funky, or the chips would wiggle as the user typed, and wiggle themselves out of connectivity. Atari's solution was to flex (yeah, twist) the computer to re-seat the chips (I used to work for Federated, and that was the official fix on Atari letterhead). Adrian, the first thing you should do on a PLCC socket system is to re-seat the chips. It would seem in addition to Atari, the Commodore Amiga had similar issues. Atari's end solution was to install clips over the chips to force them down. Sometimes the obvious and simplest (yet unlikely) fix is the solution.
Lift the chip slightly, then push it back down. Do it to all of them.
Heh yeah I've seen those ST bars -- I must say the sockets Commodore use don't seem to have these issues, at least not that I've come across. Of course there is a first time for everything right? LOL
Lessons learned: Even with clean-looking machines, always reseat and perhaps deoxit stuff before going further lol.
I'm also a machine from the middle of '88 in absolutely amazing condition!
I'm early 70's vintage and I could certainly use a retro bright 😂
This is exactly why I felt all my A500 boards were failing, until I reseated the chips... I can absolutely feel your frustration Adrian!
It was pretty common back in the day to reset any PLCC chips on an Amiga when a machine started acting up or dead, usually resulting in a perfectly functional machine. The Amiga 3000 offered double the fun on that front thanks to the ZIP ram often doing the same thing as the PLCC chips.
I grew up with Commodore 64 and later Amiga 500, I have a soft spot for this machine, with all the graphics and sound, I just love it!
I have a Amiga 600 which I purchased as faulty. I cleaned all connections and terminals
and it fired up into life and it works to this day.
Bad sockets can ruin your day ;-)
Although it also happened to make mine as well: A customer brought in 4 MSX machines of which 2 were marginal and 2 were totally dead. I fixed the 2 marginal ones and my customer said I could keep the other ones as he had written them off. I never even paid attention to them but as soon as I did: I just removed the ROM chips, reseated them and OMG both machines worked flawlessly! Sometimes you get lucky; a lot of times you don't ;-)
In my day as a repair tech we had a saying: "Re-seat the chips first". Worked most of the time :-).
The most important is that You show us how to perform good troubleshooting. Thank You
I'm always amazed that on any board you're starting with as an unknown, you don't immediately put deoxit on all socketed chips and connections, then remove and reseat them before continuing.
I loved both of these videos, Adrian. Promise I'm not secretly enjoying your frustration! It's just nice to see that not everything works out sometimes. Or sometimes you can't explain why something works again. I'm often the repair person for my family and partner's tech problems, and sometimes, I simply cannot recreate the problem they have after something like a simple reset. We think computers are simple 1s and 0s, working or not working, but somehow we've created something far weirder, almost living, even if it's just digitally. I'm glad you share these one with us and not just the stuff that works out.
I am pretty sure I sent you a machine last month that will not "self heal" considering the smoke that came out of it last time I turned it on! Good luck with that! Anyhow, keep up the great work! Even the self healing ones are interesting at least to me.
I just needed some love, sweet tender chip pressing.. She really loves good contact amongst her chips and sockets! Great work though, it's WONDERFUL to see her fixed with her original parts!! You did exactly what you're supposed to, this is just the WAY it is!!
An interesting low tech fix. It reminds me of a nightmare afternoon we had with an AV-supported lecture tour 41 years ago. We had a bank of slide projectors and a 16mm movie projector controlled by an Audio Visual Labs (AVL) Roadrunner computer [N.B. Z80 controlled]. The show was just about to start when the Roadrunner stopped working. We were able to run the show in backup reduced manual mode then send the computer for repair to a local AV company. It turns out that re-seating the Z80 did the trick.
Love this channel. I think this is a little like when i was 10 in the 70’s my mums TV wouldn’t work. I gave it a huge slap and it worked fine for the next 5 years. I think it’s down to dirt, dry solder and probably just age. I enjoyed this a lot
Thanks for jolting my memory I’m going into the loft and get the Amiga 500 which has stored wrapped up for the last 30 plus years 😎👌☕️
One thing i have noticed when it comes to even modern computers is that 'reseating' memory can solve problems. reseating all your chips may be what is healing things. the act of removing and putting the chips back in could just be re-connecting things.
My first thing to do on any non-working computer is to simply reseat every removable chip and then try again after reseating them all . That doesn’t always work but works often enough to make it my first step in troubleshooting.
The issue you're encountering is most likely chip creep. This is the process by which heat expansion causes dust or oxidization to break connections between chips and their prospective sockets. I've only ever seen it twice in my over 30 years with computers. It's fixed by simply removing and reseating the chips in their sockets. Since that seems to be what happened here, that's what I suspect.
A fun video, nice to look at the internals and hear Adrian's logic (and watching Adrian be frustrated)!
What magically fixes computers?
Flexing the circuit boards when inserting chips fixes 'bad' solder joints?
Solder whiskers?
Cosmic rays?
Space Aliens? CBA (Could Be Anything!!)
I used to tap (hit?) all the chips with the end of a screwdriver handle (rubberized) and that fixed many of 'em.
The Amiga is one of the few 80's computers I still want. I love the whole Atari-ness of it.
What I learned. Re-seat all the chips.
Blasphemy! :-) The only thing the Amiga had in common with mid-80’s Atari was the 68k CPU. Everything else was in a class of its own.
@@dans.8198 if one compares the Amiga with the Atari 8-bit they are similarly designed as it was was designed by some of the same people.
@@dans.8198 Ha!, You need to look up the history of the Amiga
@@KAPTKipper People who had left Atari; and vice-versa, some ex Commodore people designed the uninspired Atari ST series. This proves it’s all about people, not companies.
The number of computers I have fixed in my time, simply by reseating stuff, means I can well believe that was all that was needed to persuade it to work. My go to first step of diagnosis is to reseat everything that can be.
@1:10 Series 725 switches are commonly known as space invader switches, due to their resemblance to the enemy characters in Taito Corporation's Space Invader graphics
When I’m repairing retro systems, I’ve learnt that the first thing I do is to remove, clean, and reseat everything that’s socketed. Just because any old socketed connections (ICs / connectors) are susceptible to oxidation over time. It’s amazing how many systems I’ve fixed by simply reseating old oxidised connections. 🤓
I'm guessing this is why gold sockets are the go to for connection reliability 🙂 But obviously would push the cost up also. So out of the question for these low cost computers.
Step One should be to re-seat all the chips. Maybe the Agnus had a bad connection in the socket. Maybe the CPU, Gary or other chips did too.
I had opening my A500 sometimes and had enjoyed in looking at it's beautiful board ! 💓
Reminds me somewhat of when I worked for a manufacturer of communication and avionics test equipment. New product had digital control of nested phase locked loops for frequency selection. *Any* wrong output (or shorted traces) gave wrong input to the next device, giving wrong input to the next loop. So any fault at all in several different modules (and their interconnects) caused every place you looked to be wonky.
It took me a good month to develop any successful strategy to troubleshoot the units. Made worse by the fact that being newly manufactured there's no assumption possible that it had once worked or that there was a single fault. Also made more difficult by having zero known good modules to swap in until we got about the first six units working.
Learned a lot about being very systematic and thorough. And also about infant failures when components are being used beyond their data sheet limits. (Also about static electricity damage caused by stockroom handling, but that's a whole other story).
People have been griping about C= using single-wipe DIP sockets since the VIC-20 era (and probably before back into PET-land or KIM-1 :)). But I've read particularly bad things about the PLCC sockets C= used. For me, the problem wasn't usually the chip developing intermittent connections - it was me breaking the socket. Even with the right tool, even with a machine that was fairly new (2-3 years old from the factory). So, multiple remove/insert cycles on a 30+ year old socket ... I am SUPER impressed that it survived. Very courageous :D
Thats a very early model and in fantasic condition, I had a similiar Issue with a rescue A2000 which was stored in a garden shed for over 20 years. It was given to me complete with mouse nests and eaten cables. I stripped it all down, removed all the chips and gave it a good wash and alcohol bath, rebuilt it with new cables and fired it up but with a green screen. The fix was reseating the Fat Agnus chip a few times as the contacts were not as clean in the socket as I thought.
Mechanical contacts are always suspect on something this age or older. No matter how clean it may look. Reseating chips is always a good thing to try. Must have been the problem in this case.
We are witnessing a mans journey into insanity by one self healing device at the time. I still learn a ton and love the entertainment so all kudos to Adrian, keep up the good work!
It's like you have the Midas touch with vintage computers. You just touch the chips and they're healed. Thanks!
I have seen sockets cause that many a time. The first thing I do is pull each chip, reseating them and power it up. Many of an electronics device has work after doing.
Corrosion or pins getting hot has had issues, I have even seen it on cards in PC's.
Good luck, keep the videos going.
Lee
I had/have an A2000 (hard drive processor and memory board, bridgeboard 286 with memory and hard drive for that, all the bits and bobs) that got moved by car a couple of times a week, basically the routine was to reseat EVERYTHING when you got to the days destination. It's still with us.
I always thought re-socketing chips in old gear was a good first step to rule out bad connections, but assuming worst case scenario and jumping into advanced signal analysis works to 😄 Good job tho!
This is something i observed quite alot lately with old and even oldish machines. Somehow the contacts corrode over time and all you gotta do is clean them up and everything works again. I repaired some 10 year old PCs just by cleaning the RAM chip contacts for example. And old machines where repaired just by pulling the chips, cleaning everything with Isoprop and putting them back in.
Adrian, It was, and still is, common practice that for any computer/device created in the '80s & '90s were there are shocked ICs, and the computer is having any problems. To completely remove and re-seat of all the ICs in the computer/device. As the most common causes of the computer/device not working was the ICs had worked their way loose or there was oxidation on the pins and contacts. The most common reason for the ICs becoming loose was either by heat expansion and contraction. And also during shipping of the computer/device, the jostling of the computer/device during shipping causing the ICs to move and become loose in their sockets.
So, I would suggest to you that when you are first testing a system from the '80s & '90s. That the first thing you do when finding a problem with the system. To FIRST re-seat all of the ICs in the system and to use Deoxit when doing the re-seating. That way, you don't have to worry about the "Self-healing computers" again. But, I personally like even those videos.
Adrians repairs are the main reason of Deoxit sales in Oregon - it's the best tool to mysteriously repair old computers. 😇
Adrian, I think the logical conclusion we can draw is that after so many repairs, you gained the power to repair bad chips by touch 😅
LOL! So long as he doesn't suffer from Guru Meditation, we'll still have content. 😂😂
I bought an Amiga 500 back in the day and it after a couple weeks it started failing. I re-seated the chips and it worked ever since. For years never another prob.
Good video! You've demonstrated the importance of removing one socketed chip at a time, test for a change in operation, reinstall, remove next chip, etc, to find out that all that was wrong were oxidized contacts. No such thing as self-healing. You fixed it! And yes, the bonus was indeed interesting. I have 8 boxes of Commodore stuff I found after digging out my 2000 because of your battery leak repair video. I found my wife's A500 in one of those boxes. Can't wait to open it up and see what I find. Grats on another successful repair!
Re-seating chips is often the only thing needed, but also if you have a micro-crack in one of the board layers. As you change the chips that can make things move and line up.
You provide a great resource for vintage machines. Your voice is great for video work and you are interesting to watch. As someone who purchased a new Commodore 64 that failed on the last day of warranty, I took it back to SEARS where I bought it and they plugged it in and it worked! My suspicion on these systems is now a loose chip. Fast forward to 2023 and that C64 that didn't work until I drove it back to the store still runs. Thanks for providing a great resource!
Back in the day, I had an expansion setup for my A500 - I had no end of trouble with it but suspected the power supply wasn't providing a consistent supply of current...
Hell fun to have a hard drive to play Elite Frontier on!
That's an unusual combination with the proper chickenlips case and HiTek-keyboard but a rev 5 mobo and "wrong" drive.
Bad contact in socket. FIRST thing I used to do before diving deep was reseat all socketed chips. It fixed many faults.
I love the videos. You did technically fix it, since it didn't work when you started! I always enjoy these videos. Keep up the good work.
36:15 - "What have we learned here". I think you've learned to Deoxit that socket!
I get to deal with self-healing electronics and software on a daily basis. Sometimes it's better to just be glad things work at all.
Typical conversation at work for me:
Why did the machine break?
I don't know.
What did you do to fix it?
Reboot the controller several times and maybe reseat some cables.
How do we keep it from breaking again?
No idea, but hey, at least it's running.
reseating chips is a time honored tradition for repair
For six years I built IBM servers and Blades for a system integrator and one instruction I remember from the IBM certification training was to plug everything in at least twice.
I dont usually watch a whole 1hr video on something like this, but I found your presentation and method so good, I was really happy to watch thru to the end. I'm glad the Amiga is working and we all learned something along the way - reseat the chips first !
I have to give you props for making an honest video. Being that you are the one who first turned me on to Deoxit, i AM giggling a little that you didn't do the simple "reset chips" before diagnosing... live and learn, eh? ;-)
I love how the amiga can make any tech eat their words. So funny.
While I have no experience with Amigas, I learned long ago that when you have a problem with electronics that isn't software based you need to unplug all the peripherals, cartidges, socketed chips, etc; check the connectors to ensure they are clean (and possibly give them a bit of cleaning anyway), then reseat everything. Carbon buildup is a thing, and even a thin layer that is hard to see can cause issues. Making sure things are cleaned off and reseated tends to fix a lot more than you'd expect.
For quick and dirty testing, you don't need to clean perse, but at least inspect the connections and reseat.
I used to have an A600. It developed a rust spot on the disk drive head ( we had a damp house growing up ). I discovered this when it ate a neat ring in the surface of the disk. I told my brother to not use the computer until I could replace the drive ( I was technically adventurous and a drive replacement did not look hard ). I went out to a friends. When I got back I found my brother feeding the last of my game disks into the machine "Just in case". Every single one was destroyed.
I wish you would make videos that are 15 minutes long. That would be perfect playing while I fall asleep. I think these longer ones affect my sleep quality and can wake me up.
I think the bad connections are probably related to oxidised contacts. If that were the case, it would make sense for the chip to feel "in there, proper". The act of re-seating them scrapes the oxides off physically and voila - happy Amiga.
This is why they gold-plate contacts.
The quick & dirty solution to this is to reassemble with dielectric grease (regular old automotive silicone grease works a treat, but I like SGM494). Just gob it on there and make sure it goes down thw holes. It'll get displaced where necessary by the pins making contact, but otherwise it keeps the moisture out.
I used to work in an official Commodore repair centre in the late '80s and early '90s. Chips badly seated was an extremely common fault, in particular Agnus. I wouldn't be in the least surprised that the simple act of extracting and reseating Agnus fixed the issue. Faulty CIA chips were also very frequent, as were faulty floppy drives for that matter.
Excellent! You keep finding self-healing Amiga 500s. Maybe you can pick a few companies on the stock market? Your luck is outstanding!
Back in the eighties we were instructed to drop the computers from a small height onto the bench to re-seat the chips without opening the units.
I'm a fire and security engineer, even with them, sometimes disconnecting the cables and reterminating them can clear a lot of faults, especially on older installs. Can't be sure, but I've always assumed that the process simply forms a nice fresh connection between the metal and the old connection might have been just tarnished enough to cause issues.
When you're doing it for a living, you just take the easy win. The only time it's annoying is if the same fault keeps happening on the same system.
A bit surprised that Mr. Let's Dexoit was so puzzled that reseating a chip solved the problem ;-) The Agnus socket is often quite flaky, so carefully reseating the Agnus, or, if everything else fails, replacing the old socket, is often the solution. I just "repaired" a wonky A500 that crashed after a couple minutes by simply pressing on the lower half of the 68000 and reseating it that way.
The Hi-Tek-keyboard was only used on very early A500 and A2000B (that's 1987, the earlier A2000A was a made-in-Braunschweig machine and used another style of keyboard like the ones they used for their Commodore PCs). It's a bit prone to problems with the little leaf spring contacts, but the typing feel is the best of probably all machines Commodore ever built. Linear, not too light, with a nice, hard landing. People are finally realizing this and just the keyboard alone is getting sold for a premium price nowadays (and I'm probably not helping here...).
@37:20 .. Removing and re-socketing the chips is a valid troubleshooting step. ANYTHING that could move, and may get thermal cycling, can potentially develop a bad connection. Chips, RAM, expansion cards, cables, etc.
As is well known, Commodore always went the cheapest way. It could be considered a miracle that they did use sockets on the Amigas so that it's easy to replace a defective chip, but *the sockets* are the actual problem here. I have several A500s in different revisions, and most of those have some sockets that have gone bad just by existing! I've grown tired of opening the computers and reseating the chips every time I pull them out of storage, and am going to purchase a desoldering tool and some top-quality sockets. Soon. Next month, definitely this year... 😇
Often they used single-wipe sockets which are absolutely dreadful for contact issues. I replace them on sight when I come across them during a repair.
Any progress update? 🤭
There is an in-rush that happens when the spindle motor activates. It is transient, but a peak none-the-less
Number one Adrian rule deoxit that socket. I literally had an Amiga 500 memory expansion battery leak and spray through the small slit in the metal shield around it and just a tiny bit of gue hit the Agnus causing damage. Luckily minor
The only time I had an issue with an Amiga not working I was fortunate that I had two of them and was able to swap chips to find the faulty one. At the time there was an awesome shop called Power Computing in the nearest town where I got my replacement. This must have been around 20 years ago!
That's just how repairs go sometimes! I still enjoy the video.
I agree with the below post De oxit all socketed chips before attempting any sort of repair....these things have been in attics or whatever for many years.
Commodore had a problem with the very first Amiga 500s. The Agnus chip would unseat or get misaligned somehow. We used to drop our Amiga 500s about 4 or 5 inches onto a desk to reseat all of the socketed chips. Obviously, not a good practice, but it worked and was faster than taking it all apart to reseat everything manually.
Red Baron, Aces of the Pacific... some of my favorite games back in the day.
A saved Amiga is like a rescue pet. Every one needs a good home.
Bring it on. Love Commodore 64 and Amiga videos.
I had the same problem with a Gateway 80486 tower that I had sent by airmail. All I had to do was reseat all chips, even the 486, I had to actually extract it and reseat it, because simply releasing and pulling and pushing back the socket lever and cooler did not help.
You my friend have been pranked by doubting the excellent engineering of Commodore Amiga Engineers.