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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: trekiej on August 08, 2019, 03:25:00 AM

Title: Amiga 2000 Main board cleaning
Post by: trekiej on August 08, 2019, 03:25:00 AM
Hello.
I am looking to fix a mother board that had a leaky battery.
I have used Alcohol and Vinegar on it already.
It still has some green on it.
Do I need to just scrub it more or what?
Thanks.
Title: Re: Amiga 2000 Main board cleaning
Post by: giZmo350 on August 08, 2019, 04:22:36 AM
Do I need to just scrub it more or what?

Yup! Scrub it till it bleeds! LOL.....  Seriously, ya gotta neutralize the damage. Period! If there is any damage under any sockets, the sockets need to be removed and replaced (R&R). Any trace damage must be repaired. Brutal! I know.   8)
Title: Re: Amiga 2000 Main board cleaning
Post by: trekiej on August 08, 2019, 09:40:35 AM
I still have a lot to check. I do not know for sure just yet. The battery I removed looked fairly new.
Title: Re: Amiga 2000 Main board cleaning
Post by: trekiej on August 17, 2019, 01:23:37 AM
Ugh, I guess it is getting to be Dremel time.
Title: Re: Amiga 2000 Main board cleaning
Post by: amigapassion on September 03, 2019, 03:31:55 PM
Green screen means you have a chip ram issue, so cleaning will only remove the damage which is a good start. The issue will be down to damaged tracks which can be checked for continuity with a multimeter and a circuit diagram. Or you can try reseating the Agnus chip and the Gary chips. Any pics????
Title: Re: Amiga 2000 Main board cleaning
Post by: trekiej on September 03, 2019, 06:40:08 PM
This board does not have any Amiga Chips or 68000 CPU.

I do have a lot of pictures and am looking to post them on my blog.

The copper traces are shiny and still needing to remove some sockets.

I had to stop and fix my De-solder Unit. The old handle is trying to break up.
JB Weld looks like it is holding it together.

Ugh, I need more money to fix the traces.




Title: Re: Amiga 2000 Main board cleaning
Post by: thebajaguy on September 04, 2019, 04:24:19 AM
AmigaWiki has the schematics if you have a 6.2.  It's nearly the same to the left of the ChipRAM buffers on the 4.x, too.

Make a spreadsheet of common address and data lines, and common clock and bus signal lines, checking off each one from the CPU socket to the 86 pin slot, expansion bus buffers, ROM, and the ChipRAM buffers.  Mark the bad traces in your sheet with color.

At repair time, run the thin wires on the underside.

Save the clock schematics page for last - it's not critical.
Title: Re: Amiga 2000 Main board cleaning
Post by: trekiej on September 04, 2019, 12:24:46 PM
@thebajaguy
My working A2000 needs more testing.
The corroded spot is more localized.
I have put Vinegar on the spot a couple times and let dry on its own.
Wednesday night, I need to clean it again and see how bad it is.
Maybe only three lines are bad.
I still need to check all ports.
Title: Re: Amiga 2000 Main board cleaning
Post by: thebajaguy on September 04, 2019, 11:32:24 PM
Vinegar = An Acid, used to neutralize the battery leakage (which is a Base, in terms of pH)
An alternative is to use lemon juice - again, an acid.

Soak that under chip parts if you suspect some leakage got under it.
An old toothbrush is a good idea for scrubbing. 
Sockets with green in/on them should be replaced.  You can't get in the sockets well, and they will likely continue to corrode.
Badly affected chips with green are also candidates for replacement, but if not in sockets, clean as best you can, and save for later.

When done, rinse with isopropyl alcohol.  This negates much of the acid and neutralization reaction, and brings the acid/base value much closer (but not exactly) to a pH of 7 (neutral).  A 70% solution isopropyl alcohol is good enough, with the benefit that the alcohol evaporates, and the remaining 30% of that is pure denatured water - let that dry.  Avoid tap water for final rinsing if you know it tends to have a high mineral content (but it's better than nothing if you don't have the alcohol handy).  Denatured water from the store is also an option (exact neutral pH of 7, no minerals). 

Check also that any through-hole solder point (a via) conducts when it transfers the signal to the other side of the PCB.