Monitor or PCB problem - Joust

landsteam

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The game has a fuzzy picture most of the time but sometimes it looks perfect.
I checked the video cable wires all are good connectivity.
If I disconnect the video cable to the monitor the screen still comes with a fuzzy pitcure see the 1st attachment. Would this point to a monitor issue?
If the video cable is removed should the screen just come up black?
 

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As a guess, it is probably a monitor issue. My first guess woud be a cracked or cold solder connection. It looks like the horizontal hold is going out, but it is hard to tell from pictures.

ken
 
I think you must have a monitor problem, since it does it when the video's disconnected.

I STILL say you have a board problem too, though, because things like the lines through the Joust logo that are geometric and different colors can't be caused by bad cables or a bad monitor in my opinion. That's got to be a messed up signal getting sent from the board. If the whole image had lines, that could be a cable or a monitor problem, but the parts of the image that break and change color at the logo and things, a monitor can't mess up like that.

I think you've got all kinds of issues going on. They could actually be caused by the same thing though, like for instance if something's wrong in the power block at the bottom or whatever, it would mess up the monitor and not give the board the right voltage, etc. so I'm just stabbing in the dark here.
 
I think you've got all kinds of issues going on. They could actually be caused by the same thing though, like for instance if something's wrong in the power block at the bottom or whatever, it would mess up the monitor and not give the board the right voltage, etc. so I'm just stabbing in the dark here.

Yep... looks like board AND monitor issues. Lucky you.

I'd say there is some gibberish in the monitor's power... a little AC leaking through? Could just be the power block though... again, all guesses. I know I have ran a Defender on 100V (transformer blew, had to use a spare... only had a Nintendo transformer...). The screen was a little weird, size wise, but nothing like what you have. I work on a Ghosts n Goblins that had that static on the monitor... it was the chassis. No idea what it was that was causing it because I just swapped the monitor and it was gone. Never really looked into it.

As far as the colored blocked under the static... board issue.

They could both be caused by the same issue (I don't believe in dual faults too much), and the only thing they have in common is the power. Double check that transformer to make sure it's not starting to crap out on you.
 
Could the wired in power supply be causing the trouble?
The game came with a switching power supply the orginal one is not present.
The power supply is making a buzzing noise.
Also sometime it clears up and the picture is crystal clear and perfect, the game still plays 100% at all times.
 
If the power supply is causing the problem if I disconnect it the monitor screen should come up black?
If it still has the static on the screen like picture #1 then the monitor must be the problem?
 
Check to make sure the video ground wire has perfect continuity between the CPU and the monitor. I recently had a similar picture in a Defender that ended up being a broken ground wire...
 
I changed the power supply with the same results.
I also check the ground wire form the CPU to monitor it checked good with connectivity.
It is harder to fix then anything I could handle.
What should I do next?
 
If you have another game, get them close together and connect the monitor to another game to see if it is the problem. It might be a bad solder connection at the input pins, or some other issue.

If it works with another game, then you need to look at your wiring and boards...
 
If you have another game, get them close together and connect the monitor to another game to see if it is the problem. It might be a bad solder connection at the input pins, or some other issue.

If it works with another game, then you need to look at your wiring and boards...

That is exactly what I just did.
Same results I connected the video conntector into my working defender and the screen was having the same problem.
So this must be a "CPU problem".
 
Hook your Defender video cable and monitor power to the Joust monitor and see what you get.

I think you have a power or wiring problem only.
 
Is this bad to plug different games into each other for testing? Could you break a working game by doing this?

Swapping monitors is a time tested diagnostic tool. The only real danger is if you plug something in wrong. When swapping parts, it is possible, if the power supply is bad to damage a working board. That is why step 1 is always test your power with a meter. The LEDs can lie. They only indicate the minimum voltages are present.

Ken
 
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