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Neo Geo 2 Slot


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Got this in for repairs with a few other boards.

Its a NEO GEO 2 Slot, Pretty clean and untouched.

 

http://www.gamedude.com.au/images/2_slot_neo.JPG

 

Inspection looks good, nice clean PCB but I did notice the battery had started leaking and the DIODE near the battery was burnt up and the audio out sockets were broken.

 

Powered it up and get a video ram error....

 

http://www.gamedude.com.au/images/neo_problem.JPG

 

Hmmm OK time to check the video ram signals, there are two 5814 ram chips. Probing pins 9, 10 and 11 gave this result which is bad. The time base on the scope was set slow so you can see the odd rise.

 

http://www.gamedude.com.au/images/neo_what the scope showed.JPG

 

What its supposed to look like is more like this... The scope is set to the same time base so it looks a little flat line but trust me there is lots of activity. On a faster timebase you can see the ram data more clearly. The same pins are measured on the other ram 5814 next to it.

 

http://www.gamedude.com.au/images/neo_what it should be like.JPG

 

I removed the suspect ram nice and clean, no damage the way I like it.

 

http://www.gamedude.com.au/images/neo_nice clean video ram removal.JPG

 

I then moved onto the battery and DIODE, I simply replace the DIODE and removed the battery and installed a battery pack externally so no more batteries can leak on this board. I can only guess as to why the diode is burnt out but it all seems to still work after replacing it.

 

http://www.gamedude.com.au/images/neo_what the.JPG

 

After replacing all broken parts I then powered up the game board... It goes past the test but there is small defects in the graphics... ahh crap :( more work... I suspect corroded tracks as the graphics data passes through buffers near the slightly leaked battery.

 

http://www.gamedude.com.au/images/neo_crap gfx.JPG

 

Continuity tests and dexterity are needed here as there are hundreds of tracks, luckily they are usually obvious. Corrosion and dark rotted looking tracks make it easy to suss them out. As you can see a total of 4 bad tracks were found. I will laquer the PCB to help fight further corrosion....

 

http://www.gamedude.com.au/images/neo_corroded tracks.JPG

 

Ahhhh Much better!! :D

It all works....

 

http://www.gamedude.com.au/images/neo_working.JPG

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That's really cool for a noob like me to see how you troubleshoot... AND you saved a Neo Geo, nice work :D

 

Also, what's with that monitor/tv?! Looks like you've added some extra controls there?

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It took about 2 hours, that includes picture taking and wife/baby attention.

Those extra controls are voltage adjust, fan speed for internal fan on PSU and chassis/picture controls.

 

The LED display is for 5volt and 12volt... The 5volt display had some segments fail after a month or two and its to much effort to pull it all out again...:cool:

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  • 2 weeks later...
Am I imagining things, or is that monitor a converted KT-3A?

Can we get some details on the conversion to it's current form?

Or is that a state secret?

 

Dunno what a KT-3A is but I can tell you it WAS a phillips TV..

 

I have been asked a few times now to show the conversion so I guess I will have to dig the pictures out.

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  • 6 years later...

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