Karate Champ - is it the PCB or monitor?

tom11011

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Hi Group,

I picked up a Karate Champ (Player vs Player) machine the other day. It seemed to work ok but after transporting it, it has some issues I cannot identify.

Long story short, I cannot see the two players (although they are there). The monitor seems to be displaying everything but the two players who are fighting each other. I can move the joysticks and hit and kick the other player (I hear the sounds and the points register) but I cannot see the players.

But I see the background ok, just no players superimposed over the background.

Hope I'm explaining that well enough?

Appreciate some assistance thanks.
 
Something rattled loose.

Double check all connections on the pcb stack - especially interconnects and chips in sockets. Don't pull chips out of sockets unless you're comfortable doing it - sometimes that causes more problems than it solves.
 
Something rattled loose.

Double check all connections on the pcb stack - especially interconnects and chips in sockets. Don't pull chips out of sockets unless you're comfortable doing it - sometimes that causes more problems than it solves.

:)

I would pull the boards out, disconnect the ribbons. then separate them. then on like a foam block or bubble wrap, take your 2 thumbs and press down on every socketed chip. you don't have to take them out, if that were the case it wouldn't have worked at all before you moved it. moving it could have had zero influence on this as well, it could have just happened.

when finished, snap the boards back into the pushpins and reconnect the ribbons and try again.
 
cannot see the two players...But I see the background ok, just no players superimposed over the background.

first, measure the +5vdc ON the game board AND on the power supply with your trusty multimeter
hopefully it isn't over +5.35vdc or damage can occur to the chips which can happen or, the voltage is too low to power everything and you've lost a layer of graphics
maybe one of the chips is bad. before reseating all the ROMs and all that, power up game board and carefully with the back of your finger feel the chips and see if any are hot. if one is hot maybe it needs a heatsink on there to wick away the heat
those "switcher" power supply can drift over time up or down and hopefully...

weak pins inside the connector or even the connector sitting funny and not allowing electron flow needed to power up the board/stack

report back what you find there plz

good luck
 
Your problem is on page 10 of the video board schematic.
Reseating chips won't fix it.


Can you be more specific? I'm on page 30 of 43 on the KarateChamp.pdf file found on this website. This page shows in the diagram as page 10 of 12 "Schematic Set NOI-80 PCB". I also looked on page 10 of "Schematic Set NRI-80 PCB". What am I looking for here?

Or maybe you are referring to something else? Either way, any help appreciated. I plan to spend some time later today.
 
:)

I would pull the boards out, disconnect the ribbons. then separate them. then on like a foam block or bubble wrap, take your 2 thumbs and press down on every socketed chip. you don't have to take them out, if that were the case it wouldn't have worked at all before you moved it. moving it could have had zero influence on this as well, it could have just happened.

when finished, snap the boards back into the pushpins and reconnect the ribbons and try again.

I removed the boards from the arcade, separated them, and removed and re-seated all chips. Same result, no players visible. I examined the boards and can see three possible areas where there might be some issue or maybe not you can judge. Have a look at these pics.

k4co6a.jpg


1zxbfib.jpg


2ivfjg6.jpg
 
Can you be more specific? I'm on page 30 of 43 on the KarateChamp.pdf file found on this website. This page shows in the diagram as page 10 of 12 "Schematic Set NOI-80 PCB". I also looked on page 10 of "Schematic Set NRI-80 PCB". What am I looking for here?

Or maybe you are referring to something else? Either way, any help appreciated. I plan to spend some time later today.

You're apparently looking for a basic understanding of how arcade game graphics circuitry works....
 
You're apparently looking for a basic understanding of how arcade game graphics circuitry works....

Ok, are you saying the problem is found on chips that cannot be reseated? IE- board has to be disposed of? Talk to me like I'm new at this :p
 
Ok, are you saying the problem is found on chips that cannot be reseated? IE- board has to be disposed of? Talk to me like I'm new at this :p

Ignore HudsonArcade. He's not willing to help newbies.

First things first - do you have a multi-meter, and do you know how to use it?
 
How was the game transported? Was there anything that could have caused pcb damage? Something bouncing around inside the cabinet that could have bumped against the pcb stack causing damage to traces?

Mark's right, the issue is likely with a logic chip (those ARE soldered down in 99.99% of cases) but if there's a scratched/damaged circuit board trace to one or more of those logic chips in the graphics section, then it could cause problems.
 
Just a quick update to the group, I got the machine working.

What I ended up doing was buying a PCB on ebay, got an untested one for $30.

When I installed the PCB, the game was then totally pixelated without any sound or gameplay. So I separated the boards.

I used my original top board with the replacement bottom board and boom works.

I've got $230 total into this now, having a little fun with it, my daughter likes to fight dad.

Anyway, there is no way I can bring the cabinet in the house, the bottom of it is literally falling apart, its particle board. I'm debating on whether I want to get ambitious with it and maybe make a new cabinet or just play it in the garage for a while and sell it. I did the same with a pacman earlier this year, cleaned it up real good, played it for a few months then sold it for a $50 profit :)
 
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