Battery Corrosion. Need some insight.

Rookie (22)

03-03-2020, 05:44

Hi.

We just got a very special MSX, but with some corrosion around one of the internal batteries.
I already tested most of the traces, and there is continuity. One or two traces I couldn't test so far since I cannot figure out where they lead to. They pass under some ICs so I might check it later anyway.

Pls check the photos:

The machine turns on. When connected to the TV, I briefly see the MSX blue screen (but not the logo, just a blue "flash"), like a few milliseconds, then just blackness. I suppose that batteries are long dead so the machine cannot really start. Maybe it is some wrong assumption. Anyway, the "ON" LED stays on.

Once that corroded battery removed, will the corrosion continue or not anymore? Is it possible to remove it?

Also, any advice on how to replace that corroded battery for something else? I am not sure if a battery holder will fit in there. Also, the corroded battery is a 50mAh, 2Volts unit.
Also I might need to replace that ugly capacitor and a diode next it, that doesn't look good.

This is a very rare machine so I totally need to fix this thing.

Thanks beforehand.

Por Rataplan

Champion (354)

03-03-2020, 07:42

First thing is to remove the battery as soon as possible. The damage seems to be rather mild. In my days I often used vinegar to clean things up. If possible I just put the affected part in a bowl or box or whatever I had at hand, and made sure it's completely drowned with the vinegar. Is this case I'd make sure to use a soft toothbrush to remove as much leakage as possible, because yes, when it ran under a trace or chip it will just continue corroding.

You can always fit a battery holder, the question is if it fits nice or not. I wouldn't mind as being able to use safe batteries is much more important. Also, having the battery in place or not usually shouldn't prevent an msx from booting up as far asI know. Some nvram settings like startup colors would be lost obviously, but it should still boot.
What machine is it actually?

Por gdx

Enlighted (6429)

03-03-2020, 10:18

I suggest you to clean with water and a little sodium bicarbonate, dry well, scrape off the varnish a little and put tin where the tracks are damaged. Do not use vinegar!

Por rderooy

Paladin (686)

03-03-2020, 10:37

I agree with using vinegar to clean. That is what everyone does that knows how to fix these things. It neutralises the acid from the battery, something that water will not. Then use isopropyl alcohol to clean off the vinegar. Do NOT leave the vinegar on the board afterwards!

Por gdx

Enlighted (6429)

03-03-2020, 11:35

Sorry, you are right. For Alkaline batteries and Ni-Cad batteries use vinegar to clean. Then use isopropyl alcohol to clean off the vinegar. Do not leave the vinegar on the board afterwards!

Por Manuel

Ascended (19678)

03-03-2020, 22:08

Vinegar is a mild acid. How can it neutralize acid from the battery? /me confused...

Por rderooy

Paladin (686)

03-03-2020, 22:20

Manuel wrote:

Vinegar is a mild acid. How can it neutralize acid from the battery? /me confused...

Here is your answer https://www.bobvila.com/articles/how-to-clean-battery-corros...

Also works on leaking capacitors.

Por Manuel

Ascended (19678)

04-03-2020, 00:49

Aha, so there is no acid coming from the battery! That explains.

Por sdsnatcher73

Enlighted (4294)

04-03-2020, 06:25

So know you know how to clean the leak, but I am of course:

1. Curious what rare (SONY) machine you actually have
2. Not sure that the issue with the machine will be solved by removing the battery and the leak, sounds to me it has issues with the caps in the video circuitry. You can check if the machine boots fine (without video output) by listening if you hear key click or sound from an inserted game ROM.

Por Underscore

Rookie (22)

05-03-2020, 03:15

Yes, at first I will clean up that area with some vinegar to neutralize the corrosion.

sdsnatcher73 wrote:

So know you know how to clean the leak, but I am of course:

1. It is an MSX 2 machine. The last forum post about this machine was like 3 years ago. Not an extremely rare unit, but quite a bit and for me one of the best looking ones

2. It could be both. When I removed the battery, I found that it had corrosion inside. The battery is made up of two connected cell. Also it was completely dead. The other battery, a 3volt button battery, still holds a charge of 2.89volts and it looks in good shape, so I will leave it in place. Or maybe I might put a battery holder replacing the current soldered one.
The machine starts, then the screen flashes blue for a fraction of a second. It could be some issue with the video circuitry, I might need to check that part too.