My Commodore Amiga A1200 Recap (Polymer) & Repair (Colour Problem)
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- Опубліковано 26 чер 2021
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A quick recap and simple repair to my A1200! The colour problem was caused by something different on this 1200.
#commodore #amiga #repair - Наука та технологія
Note: I said I hadnt been in since 2008, that's true in terms of I haven't done anything in there - but I did periodically take the lid and shielding off and check the caps. At some point when checking it the metal tabs broke off the small shield piece you could see kapton taped down! The shield is removed in an upcoming video - best running these without the RF shield.
"Chopsticks" de-soldering technique! That's a good one!
Finally someone who doesn't twist the old caps off. 👍 Great job!
Thanks =D
Mine had leaked and ate through the pins on the hdd, half the pins broke in half. I had to remove and replace the whole connector. I like your double iron approach.
Problems with colors happen. First time I see someone checking and fixing them changing one of those small caps in the board. Great work.
Report back in about half an hour when I've got em all out 😂😂😂😂 I feel your pain
Haha, yeah - they are a pain! I hate it when systems have those holding the shield on...
Ahahaha I remember that, I laughed so much ^-^ Somewhere, in a tree, there is a nest with an Amiga key... Makes the world a more interesting place
Imagine Sir David Attenborough's voice narrating this rare finding....
Fantastic video (as usual), and timely. I have had my original A1200 torn apart to be recapped for ages. I too, purchased polymer caps -- a bit more expensive but worth it to me, especially when my original computer is concerned. Glad to see you didn't twist off the old caps -- that always makes me cringe when I see it done on old Commodore gear.
Two irons at once = soldering ninja
=D
i wish i could solder..never done it in my life and itching to have a go..not sure im brave enough yet lol...thank you kindly for your videos.
Great video - thanks. I have just had the light purple/pink show up on my A500 - aargh, but I hope this will help guide me. Thing is I also have an old A600 that my dad got the kids many years ago and it also has purple instead of white and therefore left in a cupboard. So 2no. amigas might be saved. Brilliant.
Those caps were the exact same cause of flickery colour I had on an A1200 a few years ago. When I looked all three were different colours and had different 'standards' of soldering. Replacing all three caps (22pf I think they were) and the colours came back rock solid.. :)
Nice work! I recently recapped my A1200 with the same kit that you used. I had gotten it before the end of 2020. I have to give mine a sunbathe too.
Nicely done! Something I do for smc parts is put the flux down, then put the part on top, wet the tip of the iron, and then bob in and out and it just flows in. I guess its a bit messier, but always flows perfectly every time no matter the size.
I would theorize the yellowing returns more quickly because a treatment with retrobright will strip a lot of the UV stabiliser/absorber compounds that are added to plastic. This makes the butadiene component of the polymer more vulnerable to oxidization from energy sources- heat energy that would normally be absorbed by those compounds is instead absorbed by the butadiene which breaks down in the typical way to cause yellowing (carbonyl radicals which form chromatic molecules). retrobrite and things like bright sunlight remove the yellowing because they break down those chromatic molecules faster than the same reaction is able to create them, but that extra energy (either from a strong oxidizer like hydrogen peroxide or bright sunlight) is enough to usually destroy the UV additives, too.
I've been working on my 1200 recently, some I'm loving all this A1200 content :-) I've got one last weird lingering problem I've not yet solved, the phase on the VGA output is always off when the Amiga is first powered up, but settles to where it normally is after it's been switched on for a while.
Really nice soldering work there Chris shows just how highly skilled you are.
Thanks =D
Very nifty iron work!
Thanks =D
Check all 3 resistors near the vid DB 23 connectors, I had the issue with blue-ish colors same way (R232, R231 etc)
You are right about the yellowing. Had my beige Amiga 500 and 800xl stored in a box for 12 years and I ended up with .....two bananas. I guess heat must also play a huge role in discoloration (or coloration lol). Summer temperatures here in Greece exceed 40C!
Thanks for letting me know =D
Instead of Kapton tape, I'd suggest trying adhesive aluminium foil (the "real" duct tape, used for ducts but also heating systems and chimney piping). It is amazing to protect plastics, especially when using hot air. Instead of just blocking heat it spreads and dissipates it. A single layer works for me way better than several of Kapton.
Here a roll that is gonna last me forever is even cheaper than branded Kapton, and it is also reusable several times, so for me it is a win-win
Thanks! That's exactly what I said in the live commentary for this video when it premiered lol =D
I recall seeing someone on youtube use razor blades to make a fence to protect nearby components when using hot air. I've been meaning to give that a try myself.
Proper good video. Awesome, Ive got the same board and simialr issues but with blue. Here goes nothing.
I had the same issue on mine. Unfortunately I did the videodac swap (added PLCC socket) - then chatting with Keir F he suggested C213, bingo fixed.
thank you a lot for this video..
Excellent job!
I'm going to do mine as well. It's holiday time after all ;-) Mine is a rev. 1B (with some botch wires yours is missing, I guess yours had some traces added to it).
Mine clearly has some leaky caps as well, but it should be pretty straightforward.. It's not as bad as a lot of of the Macintoshes I've repaired that suffered from pads covered in brown capacitor crud. It takes a lot of IPA, solder and flux to clean that up if the pads and traces aren't destroyed that is.. The electrolytic caps Apple used were total garbage if you ask me as most of them already started leaking after 10 years. Luckily, these one Commodore used aren't nearly as bad 👍
Love the seagull story by the way, LOL!
Oh and by the way: that resistor that appears to have been butchered off by an evil plumber must've been a mod the previous owner did to allow it to run a specific turbo card. Some of these earlier boards had compatibility problems with some accelerator boards.. The fix was to remove some resistors here and there apparantly :-)
I had an Amiga & loved it, when I started repairing them though....I much preferred the Atari ST! Amiga boards always seemed to be a pain to de-solder anything.
My A1200 has'nt had a shield for about 20 years. :)
Re: birds. Before retrobrighting, pop down to your local hardware store, agricultural store or home center and get some wire mesh (preferably with holes less than 2 inches / 50mm) and cover the tank with it. Also helps with squirrels and the like.
Lol, poor bird must've had a bad time, ingesting that peroxide. But hey, that's what you get from stealing our precious function keys ;-)
Just a thought, no idea if it would actually work. For those tricky areas like at around the 27:00 mark, what about sticking aluminium tape on top of the kapton? Its extra firmness would probably make it easier to shape/not get in the way, and I'd trust it more than the "koptan" tape I usually use
Yeah, I suggested the same thing myself in the premiere commentary =D
the yellowing is bromide leaching from the plastic, this in essence is the plastics are starting to break down into its constituent ingredients, you can keep retrobriting all you want , its a temporary measure at best
Yes, but it seems its all about ambient light too - ie. I retro brited this around 9 years ago, and it hasn't gone super yellow again due to the machine receiving ambient light. The problem seems to increase when these plastics are protected from light. I've seen the same happen to many other systems - when they go into dark storage, they yellow.
I think that when you retrobright something very yellow, it will change drastically to white, but it won't last as long as you would like. Once it's yellow again and once you retrobright it again I believe it will last longer. That's what I've seen. Anyway, it's the best you can do with yellowed plastics, you know.
@GadgetUK164: What was the temperature in the area where it was stored? If it was in an attic through a summer, I'm wondering if the re-yellowing could be a result of prolonged heating. They might simply not re-yellow before going into storage because they're kept in climate-controlled rooms?
I wonder if anyone's done an experiment to put a retrobrighted system in a low temperature oven for a few days to see if it immediately re-yellows.
It was near a radiator tbh! But since coming back out into a lit area, the yellowing has improved. Looks perfect in the room its in.
I think AmigaBill said something about the plastic that was used in commodore casings had an anti-inflamatry agent mixed i in for fire prevention and that is what reacts to UV and will Always return despite retro-brighting.
Yeah, typically the *returning* yellowing affect is when they use a bromide salt in the polymer as opposed to other flame retardants / self extinguishing agents. There's a shed load of additives, so I assume that most places that wanted mass produced cases went for the most available and cheapest additive, for obvious reasons (cost and expected life of the device).
Yeah, fully aware of what causes it, but the key point I've been trying to make is that they re-yellow super quick if put into a dark room. That's certainly my experience. And I've found from this, and the Gameboy that when exposed to light again they gradually seem to improve.
@@GadgetUK164 Yeah, my A500+ has been sat next to my window, no "retrobrighting" methods used, and the only part that has gotten more yellow is the lower case front (the bit below the spacebar) over time, and the rest of the case (and keys) has improved loads.
For the tricky work with SMD polymer capacitor with low space I use an SMD Tweezers soldering Iron (mine is marked yihua 938D), i was searching on amazon uk for one if it's possible to send you one (they cost near 50£) but they havent these soldering irons but in the french or german amazon (im french) i can find them, and yes i have done a research in english.
Do you have some kind of PO Box to send you one in?
Thanks! I will take a look =D I don't have a PO box! Thanks for the offer though =D
Have you ever worked on lead-free solder joints? Been trying to replace the caps on an old Pentium 4 motherboard and the solder doesn't melt al all, it's like the soldering iron tip is completely cold.
Yes, but I think part of your problem there is PC motherboards have several (or more) layers - they need a LOT of power from the soldering iron you use. You probably need a soldering iron that has 30w to 60w or more of power.
@@GadgetUK164 Cheers, bought a KSGER, if that fails then I can always use a hot air gun to warm up the PCB.
It's not an easy task to change the caps of the Miggy, is it?. I would say it's not recomended at all for a beginner.
Yes, I would agree!
Following the logic that stuff yellows in darkness.... why doesn't the inside yellow?
I think some people have theorised its about light weakening the outside to start with, where the inside never gets exposed to light. My 1200 is now much much brighter than when i did this video a few months back, not just from being in the sun that day, but from being out and in use daily. There are a few videos showing that sun brighting works (Vince did one), and I've seen that too. My Gameboy is super yellow from being put in a dark area - going to get that out soon and leave it out in the conservatory for a few months to see the effect there.
Nice video chap, gonna give the dual wielding a try on my 1200 modo with dodgy colours too 👍
Thanks 👍
The ceramic caps can "crack" and cause "shorts" .
Thanks, yes - seen it before where they short, but in this case it seemed to resolve after it was removed. I swapped it anyway, could have been a micro fracture inside that perhaps stopped causing a problem when heated to remove it.
@@GadgetUK164 Dave Jones did a good video on the problem, had this problem several times in video door entry phones where the only stress is the users slamming the phone down on cold callers.