Amiga a500+ battery leakage repair

Blogs & guides and tales of woo by forum members.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Amiga a500+ battery leakage repair

Post by Steve »

Just been working on @mrbombermillzy 's a500+. He had already neutralised the acid but required repair work on the eaten away traces. Special thanks to the absolutely amazing tool Amiga PCB Explorer without it this would be a nightmare. I really wish we had something like this for Atari!!!

Just a note on battery damage and how it can affect the physical properties of PCB's and solder. Firstly it can penetrate underneath the solder mask (the green protective layer) and eat away at the copper, it then spreads as far and wide as it can, through traces and vias (the holes that travel between PCB layers, front to back) When acid comes into contact with solder (on component legs or in vias) it seems to eat away the lead and just leave a crumbly crud which doesn't conduct electricity anymore. So it is really important to replace this crumbly crud with fresh solder, but - as it isn't proper solder anymore it can be super difficult to remove, it takes a lot of time and patience.

Coloured in purple are the affected areas that will need work
1. original shot beginning.jpg
1. original shot beginning.jpg (444.12 KiB) Viewed 2803 times
You can see the acid has traveled all the way up to the chip legs, this means the traces and vias will be extremely weak and I will need to be extremely careful when removing the chip for cleaning the area
2. acid on chip legs.jpg
2. acid on chip legs.jpg (200.63 KiB) Viewed 2803 times
Acid had travelled down to the ram expansion bus, so this will also require removing extremely carefully and cleaning
3. acid on expansion.jpg
3. acid on expansion.jpg (164.07 KiB) Viewed 2803 times
As mentioned before, the solder on these resistor legs are crud and so they need lifting and the vias need cleaning. I also scraped away the corrosion on the copper layer underneath the old battery and put a layer of solder over it. Normally I'd use clear over-coat but I don't have any at the moment! The diodes and resistor in the audio section also needed patching together since the trace was gone.
4.  lift all resistor legs.jpg
4. lift all resistor legs.jpg (370.96 KiB) Viewed 2803 times
Expansion header removed, ready for cleaning
5. expansion removed.jpg
5. expansion removed.jpg (268 KiB) Viewed 2803 times
Chip removed, ready for cleaning
6. remove chip.jpg
6. remove chip.jpg (235.23 KiB) Viewed 2803 times
A nice bath in the ultrasonic for the expansion pins and chip
7. ultrasonic.jpg
7. ultrasonic.jpg (345.73 KiB) Viewed 2803 times
Chip socketed, as at this point I can't be 100% sure the chip works and therefore installing a socket is important
8. finish socket chip.jpg
8. finish socket chip.jpg (342.75 KiB) Viewed 2803 times
As you can see, there is light shining through these vias now, where as before they were full of grey crud
9. light through vias.jpg
9. light through vias.jpg (461.93 KiB) Viewed 2803 times
All the broken traces are now patched up!
10. final.jpg
10. final.jpg (629.36 KiB) Viewed 2803 times
All working, yay!
11. working.jpg
11. working.jpg (335.83 KiB) Viewed 2803 times
User avatar
Badwolf
Posts: 2231
Joined: Tue Nov 19, 2019 12:09 pm

Re: Amiga a500+ battery leakage repair

Post by Badwolf »

Well done, Steve!

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
User avatar
PhilC
Moderator
Moderator
Posts: 6016
Joined: Fri Mar 23, 2018 8:22 pm

Re: Amiga a500+ battery leakage repair

Post by PhilC »

Nice explanation of the repair @Steve , it's surprising how far away the acid can go if given a chance.
If it ain't broke, test it to Destruction.
User avatar
mrbombermillzy
Posts: 1441
Joined: Sun Jun 03, 2018 7:37 pm

Re: Amiga a500+ battery leakage repair

Post by mrbombermillzy »

Great job Steve! :D

2MB Chip RAM, I cant wait... :cheer:
User avatar
mrbombermillzy
Posts: 1441
Joined: Sun Jun 03, 2018 7:37 pm

Re: Amiga a500+ battery leakage repair

Post by mrbombermillzy »

And here we have the returned motherboard fitted back into its immaculate A500+ case...

P1040080.JPG
P1040080.JPG (66.71 KiB) Viewed 2629 times

Now to (very quickly) test it. Ive managed to grab a floppy set of the game Road Rash. (Please excuse the mess in the background!)

P1040079.JPG
P1040079.JPG (83.43 KiB) Viewed 2629 times

Looking good Steve, thanks. :D

Of course, I have yet to perform thorough testing and the ultimate test is being used with a CPU accelerator drawing more current through those copper veins, but that's for another day, spare time being at an all time low ATM. :(

However, it looks like Steve has done a great job here, and he doesn't muck about time-wise either! :lol:
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Amiga a500+ battery leakage repair

Post by Steve »

Awesome thx @mrbombermillzy :)
calimero
Posts: 34
Joined: Sun Nov 05, 2017 11:27 pm

Re: Amiga a500+ battery leakage repair

Post by calimero »

Nice work!

What should I use to clean motherboard from Battery acid?

And what to use in supersoonic bath?
using Atari since 1986.http://wet.atari.orghttp://milan.kovac.cc/atari/software/ ・ Atari Falcon030/CT63/SV ・ Atari STe ・ Atari Mega4/MegaFile30/SM124 ・ Amiga 1200/PPC ・ Amiga 500 ・ C64 ・ ZX Spectrum ・ RPi ・ MagiC! ・ MiNT 1.18 ・ OS X
User avatar
stephen_usher
Posts: 5578
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: Amiga a500+ battery leakage repair

Post by stephen_usher »

The NiMH battery juice is actually an alkali and not an acid. To neutralise the chemical you can use white vinegar and then clean with water.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
PaulJ_2.0
Posts: 571
Joined: Sat May 11, 2019 11:32 pm

Re: Amiga a500+ battery leakage repair

Post by PaulJ_2.0 »

Nice work, I like to spend spare time repairing 500+ boards and getting them back in service, it's quite rewarding.

For future reference:
Those logic chips can be tested in a TL88 eprom programmer, the bundled software has a test.
It's a cleaner look to run the patch wires on the underside. Tops side is of course functionally fine though :)

Oh and well done on removing that header for the expansion port without messing it up. Those can fall to bits easily.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Amiga a500+ battery leakage repair

Post by Steve »

PaulJ_2.0 wrote: Fri Oct 22, 2021 9:21 am Nice work, I like to spend spare time repairing 500+ boards and getting them back in service, it's quite rewarding.

For future reference:
Those logic chips can be tested in a TL88 eprom programmer, the bundled software has a test.
It's a cleaner look to run the patch wires on the underside. Tops side is of course functionally fine though :)

Oh and well done on removing that header for the expansion port without messing it up. Those can fall to bits easily.
Cheers Paul. Yeah I ran fresh solder through the entire expansion port first to 'loosen up' the cruddie grey solder, then used my desoldering gun & then a little blow of the heat gun to just loosen it out without pulling traces.
Post Reply

Return to “MEMBER BLOGS”