Battery Corrosion repair

Fox1 · Oct 18, 2013

So I just picked up this broken 4 slot and after I removed the battery....low and behold:

Now what's good (I guess) is it looks like it didn't spread past that area in the photo. Cleaned it with baking soda and rinsed the boards off. Currently drying them out for 24 hours. I currently get a mix of green screen and garbled junk on the screen. Before I start replacing things (like the oscillator) , what would be good place to start? What would be a good place to start?

Tyranix95 · Oct 18, 2013

Ohms test each and every one of those traces.

Any trace that either looks iffy or does not zero out: Repair with Kynar wire.

(Iirc, Radio Shack used to have a good deal on the stuff.)

And keep an eye on the corrosion. If it looks like it is coming back, then clean the board again.

Xian Xi · Oct 18, 2013

Use a fiberglass pen to remove the corrosion from the traces then seal them up with nail polish(non-metallic). Sometimes dark spots are where the cuts in the traces are. But you need to check any of the ones that aren't green.

Fox1 · Oct 18, 2013

Sounds good. Thanks you 2!

channelmaniac · Oct 18, 2013

Stuck on green = calendar error.

Check the continuity from pin 14 on the D4990 clock/calendar chip back to the battery area of the board. The +5v to run the chip comes from the backup battery circuit so a corroded trace or plated thru hole will cause that.

Fox1 · Oct 19, 2013

channelmaniac said:
Stuck on green = calendar error.

Check the continuity from pin 14 on the D4990 clock/calendar chip back to the battery area of the board. The +5v to run the chip comes from the backup battery circuit so a corroded trace or plated thru hole will cause that.

When you say back to the battery area, you mean the two pins where the battery was? If so I checked that and I get a momentary connection I guess is the best way to put it...

channelmaniac · Oct 19, 2013

No silly... Go to pin 14 on the D4990 and make sure it has +5v on it when the board is powered up. If it doesn't, trace it backwards to the battery backup circuit and fix where it stops.

xsq · Oct 19, 2013

just one small tip: if the battery originally installed on your board read "Ni-Cd", the leakage will not be acidic, but basic... so you should rather use vinegar than baking soda to neutralize it.

Fox1 · Oct 19, 2013

channelmaniac said:
No silly... Go to pin 14 on the D4990 and make sure it has +5v on it when the board is powered up. If it doesn't, trace it backwards to the battery backup circuit and fix where it stops.

Oh when it's powered up, roger that! :P

xsq said:
just one small tip: if the battery originally installed on your board read "Ni-Cd", the leakage will not be acidic, but basic... so you should rather use vinegar than baking soda to neutralize it.

Oh, yeah it was Ni-Cd...okay I'll use vinegar

Fox1 · Oct 19, 2013

Ok I checked the power on pin 14 and it was getting +4 on it.

channelmaniac · Oct 19, 2013

Too low!

Fox1 · Oct 19, 2013

channelmaniac said:
Too low!

Ok I fixed it and cleaned it off some more..I checked all the suspect traces and oddly enough they seem fine, but now I'm getting this screen:

channelmaniac · Oct 19, 2013

How did you fix it?

Something you did broke something else.

Fox1 · Oct 19, 2013

channelmaniac said:
How did you fix it?

Something you did broke something else.

Power supply wasn't giving enough juice, switched it. It certainly seems like I broke something else although I have no idea what since I really haven't done much other than replace a capacitor and crystal since they were shot.

Xian Xi · Oct 19, 2013

Make sure you check the traces as well as the plate-throughs. It might be fine from A to B but if you check the under side the plate-through might not be good.

Tyranix95 · Oct 19, 2013

New board pic.

Fox1 · Oct 19, 2013

still getting crap off of it

Xian Xi · Oct 20, 2013

Are you testing the full board or just the bottom board?

Tyranix95 · Oct 20, 2013

Xian Xi said:
Are you testing the full board or just the bottom board?

What I was going to say.

Split the boards: Boot just the bottom board. Report.

The pair the boards: Boot up: Report.

Fox1 · Oct 20, 2013

Tyranix95 said:
What I was going to say.

Split the boards: Boot just the bottom board. Report.

The pair the boards: Boot up: Report.

Tried them both, same result.

Tyranix95 · Oct 20, 2013

When you boot up: Do the speakers make a clicking noise?

Also, when you boot does the game go straight to the garbage screen, or does it start like normal and then post the purple junk on the screen?

Fox1 · Oct 20, 2013

Tyranix95 said:
When you boot up: Do the speakers make a clicking noise?

Also, when you boot does the game go straight to the garbage screen, or does it start like normal and then post the purple junk on the screen?

I don't hear a clicking noise. Let me correct my last post. With a single board it does that checkered pink/blue/whatever screen, but with the 2nd board on top it does a tanish/pinkish line on top of the screen.

Edit: Actually it's quite random on what it does with the top board on.

Most of the time it does this:

Some of the time it does this:

And some of the time it does that the same screen as the one without the top board on. This thing has a mind of its own..

Tyranix95 · Oct 20, 2013

The garbage on your screen means that your CPU is crashing.

Different things can cause a CPU to crash: A bad CPU, A bad BIOS Rom, a bad Crystal, a bad logic chip or chips, bad Ram, or bad Traces.

1) Use a Multi-Meter to ohms check any trace that does not look BRIGTH GREEN, from point to point, in general battery area. You need to double check and make sure all traces in the battery area are good, from point to point. Esp. those involving the the Clock and the 4990 chip.
2) You can use an eprom programmer to check (verify) the BIOS chip.
3) And you can use a logic probe to check the CPU and the Clock. Check pin 16 or 18(?) to see if it is HI on or Low on the CPU. And check the legs of the Clock and see if you get any signal.

Considering your board has a bad battery, I'd focus on "corroded" traces and parts, in the general battery area, first, before touching other parts.

4) Or, if you don't want to mess with it: You can always PM CM and see if he can repair it.

Fox1 · Oct 20, 2013

Tyranix95 said:
The garbage on your screen means that your CPU is crashing.

Different things can cause a CPU to crash: A bad CPU, A bad BIOS Rom, a bad Crystal, a bad logic chip or chips, bad Ram, or bad Traces.

1) Use a Multi-Meter to ohms check any trace that does not look BRIGTH GREEN, from point to point, in general battery area. You need to double check and make sure all traces in the battery area are good, from point to point. Esp. those involving the the Clock and the 4990 chip.
2) You can use an eprom programmer to check (verify) the BIOS chip.
3) And you can use a logic probe to check the CPU and the Clock. Check pin 16 or 18(?) to see if it is HI on or Low on the CPU. And check the legs of the Clock and see if you get any signal.

Considering your board has a bad battery, I'd focus on "corroded" traces and parts, in the general battery area, first, before touching other parts.

4) Or, if you don't want to mess with it: You can always PM CM and see if he can repair it.

I'll check everything again, appreciate it.

Tyranix95 · Oct 20, 2013

Something to read while your checking things over.

http://www.neo-geo.com/forums/showt...-screen-before-booting&highlight=4990+crystal

Battery Corrosion repair

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