Amiga motherboard repair A500+

[roy bates]

i found this on youtube,so i thought i would post it here as there has been alot of amigas comming out of attics and basements lately.


i found the video to be usefull and informative,and its the way i would do it,enjoy


[ Show youtube player ]


also i think this video is relevent for other amigas as well,not just amigas with battery damage.

[TjLaZer]

thanks for that link, yes good and detailed info.

[A500Man]

Well,

the video contains all the infos needed. And the guy knows a lot about Amiga ....

But there have to be made twoo remarks:

1) The video is -erm- quite loooong ... ....
2) The amiga worked before the repair! How do I know? Well, how can the owner tell him, that it does not boot from the floppy-disks ... Yeah, because the Amiga itself was/is working fine (despite the corrosion), just the disk-drive has gone nuts ...

Please do not get me wrong, that guy is really good with his soldering iron and knows exactly what he does. But the corrosion on this board is a very light one. I have seen boards where every ICs in a 3-inch-range from the battery had corroded. And the place where the battery used to sit was covered with white chrystals. No hope left ... So, the guy in the video has not "revived" the Amiga, but he surely saved that Amiga from dying in a not too far away future ....

CU,
A500Man

[roy bates]

@a500man

i have to disagree with you on the comment of light corrosion,the traces he repaired where nearly eaten all the way through and the ic he replaced did need replacing becuase of it along with other parts with corrosion on them.(which if you dont know,is the point of a repair)

i dont know weither the video was too long really,how long does it take to repair one of these machines.....


yes we have all seen worse,but using the word revived wasent far from the truth as it clearly dident work properly when it was shipped to him.

the video is for reference only,and not really to be taken as is due to every case is mostly different.(the video is of one case with very specific problems that wont neccesarally relate to anyone else)



also i would like to point out if this video was to help everyone with there problems individually,it would be several videos and each video would be several hours long......if you get my point

[TjLaZer]

Originally Posted by A500Man

2) The amiga worked before the repair! How do I know? Well, how can the owner tell him, that it does not boot from the floppy-disks ... Yeah, because the Amiga itself was/is working fine (despite the corrosion), just the disk-drive has gone nuts ...

Actually I think you are mistaken. The previous owner had removed the leaking battery and did some clean up. And at this stage I believe it caused the A500 to not work anymore. So when it arrived at this guys place it was in a NON working state.

I have had Amigas working with leaking battery, then when I removed it and cleaned the area, it stopped working. Probably due to corroded traces getting "cleaned away" due to being heavily corroded.

[fitzsteve]

Originally Posted by TjLaZer

Actually I think you are mistaken. The previous owner had removed the leaking battery and did some clean up. And at this stage I believe it caused the A500 to not work anymore. So when it arrived at this guys place it was in a NON working state.

I have had Amigas working with leaking battery, then when I removed it and cleaned the area, it stopped working. Probably due to corroded traces getting "cleaned away" due to being heavily corroded.

Same happened with my first A500+

[TomCrazy]

Thanks a lot Roy for spreading the word. Really appreciate it.

It seems like the repair I did on this A500+ has caused some confusion.
I will try to clear some things up by answering to A500Man's comment here.

Originally Posted by A500Man

Well,
1) The video is -erm- quite loooong ... ....

Yep, sure is! Can't disagree with you there. However, one can ask himself whether that is a good thing or a bad thing.
The Lords of the Rings-movies (extended versions) are also quite long. Is that a good thing or a bad thing? Well, it willl of course be a negative thing for a person who is only interested in watching, say, a 1h 30min movie at the time. But there is no way Peter Jackson could ever have included all the details of the story if it had been a 'max 2h per movie'-trilogy. Squeezing an almost 4 hour movie into 2 hours without losing any details of the story is just impossible.
The point here is, of course, that the YouTube clip could have been made shorter, but that would have resulted in a loss of details regarding how the repair was being performed.
It's up to each and everyone to judge whether any video is too long or too short. Also, it depends on how interested the viewer actually is in watching the video.
If anyone goes to the movie theater and sees a movie, and then comes out saying "This movie was too long, I almost fell asleep.", then at least to me that almost means exactly the same thing as "I didn't really find this movie particularly interesting."

Btw, here is an excerpt from the description of the video:

"I know that this came to be quite a long video, but please keep in mind that this is a documented repair, not a tutorial. Fixing corroded motherboards really takes a lot of time and patience, and a lot of time has been spent just scrubbing and cleaning the board from corrosion all over the affected area, which is not included in the video. So even though this video is quite long, there are still many time-consuming things that I have done to the motherboard during this repair which are not presented here. However, I have chosen to include the most interesting and critical things I did so you can get an idea of what had to be done in order to get this motherboard up and running again."

I expect the working time on this motherboard to exceed 10 hours in total. Maybe even 15. Yes, I am not kidding. It really took that long to repair it. Like stated in the video description, many things were done that I thought I would rather skip including in the video in order to not make the video even longer than it turned out to be. That would include things like neutralizing the battery acid, scrubbing a lot with a toothbrush, cleaning the remaining chemicals off with water and then cleaning off any possible remaining minerals with alcohol... All those time-consuming commonly used methods often utilized by PCB repairmen were something that I felt didn't have their place in the video... Mainly because of the difficulties in filming all those steps and the extra work of editing it into a time-lapse, but also because it would add even more length to the video.
And then of course, browsing through the electronics store's webpage carefully making sure you order components with exactly the right values and physical size takes quite some time as well...

Originally Posted by A500Man

2) The amiga worked before the repair! How do I know? Well, how can the owner tell him, that it does not boot from the floppy-disks ... Yeah, because the Amiga itself was/is working fine (despite the corrosion), just the disk-drive has gone nuts ...

I can assure you that it certainly did not operate in a way that can be referred to as "working". Or... um, well... That depends. Is an A500+ supposed to only put out a green screen without doing anything else when you power on the system?
This is actually even included in the video. At 12:01 in the video, I clearly show you that the Amiga was (at the time) not doing anything but putting out a green screen. You cannot possibly call that a "working" Amiga, can you?
I am kind of wondering if you watched the whole video, since it seems like you must have missed the part at 12:01 when I show everyone that it wasn't working?

Oh, and about the disk drive... Using the expression "gone nuts" here would be a bit exaggerated. You are correct however in that the disk drive the owner sent with the machine was not in fully working condition. It was about half-reliable, although it did boot and load disks. But the thing is, why would anyone use a bad floppy drive when the focus is put on testing and repairing the motherboard?
Of course, a fully working original Amiga shugart floppy disk drive was used during the whole repair of the motherboard, not the half-reliable floppy drive that was inside the Amiga when it came in.

Originally Posted by A500Man

Please do not get me wrong, that guy is really good with his soldering iron and knows exactly what he does. But the corrosion on this board is a very light one. I have seen boards where every ICs in a 3-inch-range from the battery had corroded. And the place where the battery used to sit was covered with white chrystals. No hope left ... So, the guy in the video has not "revived" the Amiga, but he surely saved that Amiga from dying in a not too far away future ....

Thanks for the positive feedback on my soldering job. I guess I could never have done these kind of repairs 20 years ago, which was around the first time I modified my first console. Practice gives progress, but there is still much to learn. I would most of all like to improve my multi-pin soldering techniques when it comes to TSOPs, QFPs, PLCCs, and similar types of packages.

Originally Posted by roy bates

@a500man

i have to disagree with you on the comment of light corrosion,the traces he repaired where nearly eaten all the way through and the ic he replaced did need replacing becuase of it along with other parts with corrosion on them.(which if you dont know,is the point of a repair)

i dont know weither the video was too long really,how long does it take to repair one of these machines.....


yes we have all seen worse,but using the word revived wasent far from the truth as it clearly dident work properly when it was shipped to him.

the video is for reference only,and not really to be taken as is due to every case is mostly different.(the video is of one case with very specific problems that wont neccesarally relate to anyone else)

also i would like to point out if this video was to help everyone with there problems individually,it would be several videos and each video would be several hours long......if you get my point

You really nailed it down there, Roy! Couldn't have said it better myself.
At 22:05 in the video, we can clearly see on the close-up that a trace has been completely eaten through by the corrosion, and is completely cut off from the solder pad. So one trace was actually completely eaten through, not just nearly. A few other ones would however fall under the "nearly"-category. And those had to be taken care of in order to make the Amiga last longer than just 1 month or so after sending it back.

What is referred to as an Amiga "being dead" and/or "being revived" is something I consider to be more of a language related topic, and is to me a subjective matter. Since it's a matter of personal use of language and definitions, it's pretty much impossible to say what is the truth and what is not.
Did I "revive" the Amiga? Maybe I did, maybe I didn't. But actually, I don't think it really matters that much. It's just a word, just a definition that we choose to look at in a different way. But, one thing is for certain: The Amiga was not working when it came in, and it was working perfectly fine when I was done with it. I might not be a native English speaker, but I am quite sure that it would be perfectly plausible to use the verb "to repair" in a such a situation. So my conclusion would be that whether I revived it or not, I did certainly at least repair it. Goal achieved! And that's what matters, right?

But, just to give you my own opinion on the matter (although it is a subjective matter, like I said):
No, I don't think I really revived the Amiga in all it's true meaning. Because you can not revive something that is not dead. Was it dead? Not really, I guess. To me, a dead computer system is when you turn on the power and nothing (and I really mean nothing) happens. The LED doesn't even come on. I have repaired Amigas like that. The most recent one, which I still have a clear memory of, had a not so much surprisingly power failure caused by a broken 5V supply trace on the board.
That one I did revive. Well, in my opinion at least.
This A500+ was not dead. It just wasn't functioning properly, since it only gave me a green screen on power-up.

Exactly, the point of the video was not to help anyone with their individual problems. The procedures during a repair of this type really have to go on a case-by-case basis. No two situations will be exactly the same. Every repair has an inspection and evaluation stage, with course of action based on the result of the evaluation performed. Therefore, as far as corrosion goes, it's almost impossible to make any kind of video that pinpoints one certain situation.
What I am doing is documenting the particular job I have at hand, so that those who are interested in following me can do so if they wish. But of course, even though corrosion has to be dealt with on a case-by-case basis, hopefully beginner electronic enthusiasts / repairmen will be able to pick up some useful ideas from watching some of my stuff.

Also, I can confirm that everything TjLaZer says in his post is absolutely correct. There is just one thing; It was with 99.9% certainty not the removal and cleaning of the area (performed by the owner) that made the Amiga stop working. It was the corrosion caused by the leaky battery that did. It was already in a non-working state when he took it out from the attic, and that is what led him to opening up the machine only to find a lot of corrosion around the battery. So he decided to take the battery out and clean the area as good as he could, without any success of getting the Amiga to work again. This is when he decided to send it over to me.
What can be seen at around 22:06 in the video is not the result of a Q-tip with alcohol on it rubbing against the PCB. The "edgyness" or "jagginess" seen on the traces and the solder pads, especially at the points where they have a break or are close to having a break, is not something that a human hand could ever have caused. Those are typical signs of copper having been eaten away and partially or completely damaged by the corrosion.
I have seen several cases of this and it has basically looked in a similar fasion every time.
But of course, corroded traces are much more fragile than undamaged ones, so they can easily be damaged during cleaning of the PCB and desoldering of old corroded components. So I do not doubt for a second that such a thing has happend to people before. But that was not the case here with this A500+.
Btw, when traces are really corroded, there might be just a tiny fraction of the width of a certain trace that is still conducting electricity. It doesn't take much for that last conductive part of copper to snap off, which inhibits current flow through the trace, making the Amiga not working anymore. In such a case, I hardly think the Amiga would have kept working more than a month if the corrosion had been left on the board as it was. The corrosion would quickly have eaten its way through that last fraction of the trace. So it doesn't really matter that removal of the battery and cleaning tore that last fraction of the trace off. Because if cleaning hadn't caused that last piece of copper to snap, the corrosion certainly would.
So working or not working is really not the issue here. If there is any corrosion, then that corrosion and the damage it has caused has to be dealt with, no matter the current status of functionality of the machine.


I hope this clears up a few things.

A lot of thanks to everyone who sees this post and have been watching my videos and given me positive feedback. Really appreciate it.
I will try to continue documenting my repairs as long as there is people out there interested in following me on what I do.
Thanks again.

TomCrazy / RetroGameModz

Wotcha!!
I'm a newbie here, sorry!
i have 2 A500+ motherboards both not working, i presume due to leaked batteries. one is very severe leakage and i get a green screen. the other isnt too bad really but i get just a black screen. i think the socketed chips are ok but a few capacitors and a couple of soldered chips have that green gumpf/corrosion on. would this green stuff (not a copious ammount) be enough to stop the old girl working? i think the badly corroded one is a dead duck though. anyone interested in it? i'm not patient enough to unsolder and re solder many capacitors!!
cheers!