User avatar
halfbrite

Posted Fri May 06, 2022 6:49 am

I have a pretty big ultrasonic cleaner, can fit the Amiga motherboard at an angle I think.

It of course has the leaky battery, and I want to remove the existing crust, and stop any further damage.

My thoughts are to perform the following steps on the motherboard.

- Clip off battery and remove legs
- Remove all non-soldered components (May skip the ZIP ram)
- Clean around the motherboard where it look like acid got to with white vinegar. Suggestions how?
- Run through the ultrasonic cleaner the motherboard with a cleaning solution - Any recommended liquid solutions?
- Run through the ultrasonic cleaner the motherboard with 99% IPA.

Clean all the removed chips by hand.
Assemble and smoke test.

User avatar
obitus1990
USA

Posted Fri May 06, 2022 5:23 pm

Unless you want a fire, don't run 99% IPA as your solution in an ultrasonic. Ultrasonics by design warm the solution they contain, and, you could hit the flash point for that alcohol. Clip the battery, remove the legs from the board, get a new toothbrush and scrub it down with something to neutralize the battery's leaked BASE (it's not acid) like white vinegar, rinse with 99% IPA, followed by distilled water. Branson EC is a good one to use in the ultrasonic after that, and then another rinse with distilled water, followed by complete drying of the board. Blow it out with compressed air and then either let it air dry for a few days or put it in an oven at 115F for an hour.

User avatar
halfbrite

Posted Sat May 07, 2022 10:33 am

obitus1990 wrote:
Fri May 06, 2022 5:23 pm
Unless you want a fire, don't run 99% IPA as your solution in an ultrasonic. Ultrasonics by design warm the solution they contain, and, you could hit the flash point for that alcohol. Clip the battery, remove the legs from the board, get a new toothbrush and scrub it down with something to neutralize the battery's leaked BASE (it's not acid) like white vinegar, rinse with 99% IPA, followed by distilled water. Branson EC is a good one to use in the ultrasonic after that, and then another rinse with distilled water, followed by complete drying of the board. Blow it out with compressed air and then either let it air dry for a few days or put it in an oven at 115F for an hour.
Thank you very much, oops on the base :) And a VERY good point on the alcohol, wasn't thinking about the heat.

User avatar
halfbrite

Posted Tue May 10, 2022 8:11 pm

So, I pulled the mother board to check the bottom, was pleasantly surprised as was expecting the worst, very little signs of corrosion.

The super Denise was not so lucky, Surprised it worked. Hopefully the lack of 2mb of chip ram is something simple.

That spot was pretty big after clipping out the battery!

Some vinegar treatment next.

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User avatar
halfbrite

Posted Wed May 11, 2022 11:20 pm

So after a long soak in vinegar targeted with paper towels, as well as cleaning the chips that had green.
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Some scrubbing with a brush, cleaning with IPA and then removing all chips and rinsing with distilled water I had the following. U477 had the most corrosion of any chip, but the legs are solid and it doesn't look like it went into the chip. Looks like a logic chip so would like to know what it is used for.

I removed the + legs on the batery no problems of course, VIAs look a bit trashed, but the ground plane is of course a pain. I don't have a lot of experience dealing with that, I assume I just need a hot large tip iron. So for now its stuck in there still.

I also need to figure out if any traces were damaged under the resistor. Anyone have any experience with checking those traces and where they go. Otherwise off to digging out schematics and looking for the lost silkscreens that labels the resistor and the cap.

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Also on close inspection of the bottom of the board I had a burned out trace. Was a bugger to solder to the remaining trace, didn't think I could get the VIA. This went through to something under the SCSI and Serial port tower.

I have seen traces burn out like this when too much voltage goes across, anyone know if this is a common thing?

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Last edited by halfbrite on Thu May 12, 2022 10:50 am, edited 1 time in total.

User avatar
dalek
Australia

Posted Thu May 12, 2022 12:29 am

Generally you want to go vinegar -> water -> IPA. The water washes off the vinegar and the IPA helps evaporate excess moisture.

For checking traces get Sprint Layout demo version and the ReAmiga 3000 9.4 files.

But your board is looking pretty good!

User avatar
halfbrite

Posted Thu May 12, 2022 10:55 am

Thanks for the tips! I have a mac, so cuprum https://apps.apple.com/us/app/cuprum/id1088670425?mt=12 on the appstore was free, and works great for the gerber files.

What a life saver, took 10 seconds to see the traces and where they go! So for anyone with battery damage this is for you for sure. Good news is they are all still intact.

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User avatar
halfbrite

Posted Mon May 16, 2022 12:19 pm

I got the coin cell battery installed, never realized my hakko could be reset by pressing both front buttons, powering on then releases the front after 10 seconds. I could then hit up and then enter and it resets to factory calibration. Somehow I must have messed it up over the years. It's 65 watt and that with flat tip fixed all my issues with desoldering the ground plain and installing the coin cell holder.

Did some paint and a bodge wire since the vias were ruined for the positive side. Tested and it keeps time.

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User avatar
halfbrite

Posted Mon May 16, 2022 12:24 pm

So I ran Sysinfo on the board, it shows 25mhz, cool.

It also shows the 1mb max for chip ram.

I have tested power at the sockets for the extra mem, I have also check common trace points for the OE, CAS and RAS.

Basically the sockets seem fine so I assume I have to focus on chips around the battery damage.

If anyone has any pointers would appreciate it.

I am thinking of focusing on U477 and U480 first. I would assume if I did have problems with Denise, it would manifest graphical issues but games seem good just running them in demo mode.

I assume the ram is good, I have no way of testing and the sockets are good, but that the system is not detecting or selecting the second bank.

User avatar
Sanxion

Posted Mon Feb 06, 2023 2:27 am

Hi

I am in the same process as you were, cleaning corrosion from my A3000 motherboard.
I have a couple of questions:
1. How is your board now?
2. What did you use to paint the corroded area under the battery?
3. Have you done anything since to the board?





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