User avatar
moray

Posted Sun Apr 10, 2022 8:45 am

Hello,

I posted a while ago a couple of pictures of the battery area of an Amiga 3000 I got (with a bit of luck :)).
The battery leakage was not at all visible at a first sight but after snipping it out I discovered a small spot under it and noticed some solder joints of near components were slightly affected.

I cleaned with vinegar and alcohol, scraped a little bit the solder mask of the spot and then... well I had to shelve the project until yesterday.

I would like to clean this area up throughly and I have a couple of questions for anybody used todo this kind of work (I did a little soldering but not at all expert).

- I am having trouble reflowing a couple of joint that are on larger ground plane, in particular it took me a bit to clean the ground pin of the battery, also because of the corrosion.
What is the best practice? I try to add solder (and flux) n the joint on the back of the board and then use the solder pump, but I can't get all the solder out.

- Picture attached, I still have to fix a couple of solder points but my question here is: are there any other components I should be worried about? Like what about the caps near paula (C411, C412...), The solder joints seems dull.. also the components on the other side R470 and up (I did the first two).

Thanks in advance!

P.S.
This Amiga 3000 is actually a UX version, the serial number on the back of the case is CA0000411 made in california, but the board has a sticker with a different serial number. Anybody has info about those?


Image

User avatar
dalek
Australia

Posted Sun Apr 10, 2022 4:43 pm

My technique when I hit a large ground plane is to use a heat gun to pre-warm the area. If you can get someone to hold it, continue using it while desoldering with the iron/desolder gun. Adding fresh leaded solder+flux beforehand does help too. A larger iron tip and iron that can sustain higher temps is also a good idea.

Everything there looks pretty good actually. If you are concerned you could do a second vinegar clean and wash off with IPA, or use a fibreglass pen to shiny up the leads. But it doesn't look necessary to me.

If it's not working after cleaning socketed chips and sockets with contact cleaner and reseating all chips, your next best bet is to use diagram to try and isolate the issue.

User avatar
moray

Posted Tue Apr 12, 2022 9:05 am

Thanks for the tips!
I unfortunately don't have an heatgun or desoldering gun.. yet.. And I am having difficulties with other components too so I will order at least the heatgun.

In the mean time I received another Amiga 3000 motherboard that has more visible corrosion, but it works. I spent all day cleaning it.
I noticed that many vias around the battery on the front and on the back of the board were black, I thought some traces were damaged so I scraped them with an xacto-knife and uncovered the copper of the via and the trace adjacent, I didn't find any broken traces (and tested with the multimeter). The vias are exposed now but I wonder what should I do to clean the hole as in many cases it is black..

Whit this one I had to remove U480 as the pins were very corroded and green and I will probably replace the components around it, and while removing it a couple of pads disappeared, I wonder if they were corroded or I did that.
I snipped the legs and then removed them while heating the pad from the back of the board, but as usual, the pins on the ground plane are super difficult and I can't seem to clear them...

P.S.
I thought I would live some updates for whoever is looking for cleaning up an A3000

User avatar
halfbrite

Posted Thu May 05, 2022 7:08 am

You should re-cover all the exposed copper if you can, there are coatings available for this, I of course cant remember the name. There are also color matched ones, like green, etc. Pens that will do this that work OK. Overcoat pens maybe?

I am by no means an expert, but I think the UX version would have came with a 3 button mouse and maybe hardware for using tapes? I think everything else would be just regular hardware upgrades like more ram, etc.

It of course would have shipped with Amiga Unix :)

My 3000 I just acquired has similar damage to your first one, will let you know what I find and do.

User avatar
halfbrite

Posted Thu May 05, 2022 1:44 pm

This is what I see so far, just looking at photos. Maybe I will get lucky with just removing a few chips and a vinegar bath followed by an alcohol shower?
Image

User avatar
McTrinsic

Posted Thu May 05, 2022 2:14 pm

Sorry to crush your hopes. But the acid may crawl under the lacquer and destroy more elements. Think of rust. Get some help for this board.

User avatar
halfbrite

Posted Thu May 05, 2022 2:53 pm

McTrinsic wrote:
Thu May 05, 2022 2:14 pm
Sorry to crush your hopes. But the acid may crawl under the lacquer and destroy more elements. Think of rust. Get some help for this board.
Sure, whats your advice for get some help?

Other than stripping it down and cleaning well, remove the battery, etc.

Thank you!

User avatar
intric8
Seattle, WA, USA

Posted Thu May 05, 2022 2:54 pm

I had one of my A3K's sent to an ultrasonic cleaner/bath. It does a remarkable job of removing harmful acid particles we can't even see. Like, behind or underneath areas you'd never even think to look.

User avatar
obitus1990
USA

Posted Thu May 05, 2022 7:48 pm

I have an A3000 that I purchased with similar signs of corrosion. I desoldered every single component and socket in the area that had even a tinge of corrosion, then sanded off the solder mask to bare copper, checked for continuity in all traces, cleaned it in an ultrasonic, re-tinned the traces, through holes & vias, then recoated the exposed copper traces with a UV cured solder mask.

You have a lot of work ahead of you to mitigate that if you want to keep the system running...and it will not be an easy desolering job due to the large ground planes the A3000 possesses. I feel your pain.

User avatar
McTrinsic

Posted Thu May 05, 2022 9:55 pm

Hi,

to answer that question: open a new thread / request on this forum and ask for help. Or do something similar on other forums that you trust.

Content-wise, see Obitus‘ answer.

Cheers,
Erasmus





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