Wells Gardner 19" K7200 Red Screen/Backgrounds, Can't fix

[teesee150]

I'm trying to build a replica Ms Pacman Cocktail, and the first monitor I bought was cracked, so now I just got a second monitor in and I'm having issues with it. I believe its a Wells Gardner 19" K7200 (at least it looks exactly like my old K7200), manufactured in 2004. When I power the monitor up with no signal, I get a red screen with scrolling lines. When I boot it up with my 60 in 1 Jamma board, I have the same red screen, but the lines stop scrolling, and I can see the games, but it's mostly a red screen.

Trying to adjust the red driver and red cutoff on the neck board as zero effect on the screen. I have tried adjusting brightness and contrast as well and cannot get the red to even remotely come close to going away. I've tried searching for solutions and haven't been able to dig anything up yet. I double checked my connections from the Jamma board as well.

Any help would be greatly appreciated.

I've got a few pics as well:

Running a game:
Running a game 2:
Running a game 3:
During Jamma board boot up:
Monitor powered on with no video signal:

[iankellogg]

inspect the neckboard and look at those red drive/bias pots to see if any of the legs are broken. It seems to happen a lot on the k7000 monitors. While you are there use your multimeter to check if the pots actually work by measuring their resistance as you turn them. Finally do a diode test on the color transistors, make sure none are shorted out. If everything checks out we may have to go back to looking on the main board.

[John's Arcade]

Most likely a neckboard issue. Check the color drive transistors and the traces around them.

You can swap the transistors around to see if the problem moves. Meaning, if the red transistor is stuck on, swap it with blue and if blue is now stuck on then there is your issue.

[teesee150]

inspect the neckboard and look at those red drive/bias pots to see if any of the legs are broken. It seems to happen a lot on the k7000 monitors. While you are there use your multimeter to check if the pots actually work by measuring their resistance as you turn them. Finally do a diode test on the color transistors, make sure none are shorted out. If everything checks out we may have to go back to looking on the main board.

The legs on the pots are connected. Visible checked than also checked with the multimeter by testing for a short with one lead on the pot itself than the other lead on the back of the PCB on the leg sticking thru. The resistance also changes on the pots as they are turned.

Moving on to the color transistors now.

[teesee150]

I swapped neck boards, didn't work at first but I rechecked all connections and now it works...awesome.

Thanks for the help everyone. I still need to find out what was wrong with original board, but at least its up and running.

[teesee150]

Can anyone tell me if these vertical lines are normal in a monitor? I can adjust the flyback and get them to almost disappear, but they are still slightly visible




After adjustment

[iankellogg]

They can be caused by either bad caps or just over driving the guns. Often there is separate brightness control other than the screen control on the flyback. If you can't adjust it out with the pots then you may need a cap kit. If even after the cap kit they are still there you may need to rejuv the tube.

[teesee150]

They can be caused by either bad caps or just over driving the guns. Often there is separate brightness control other than the screen control on the flyback. If you can't adjust it out with the pots then you may need a cap kit. If even after the cap kit they are still there you may need to rejuv the tube.

I've been playing with the adjustments and got it looking really good right now. Appreciate the help!

[BaldiGit]

Just a thought.... I have the same lines on my cabinet. But only when there's no signal to the monitor. It's a WG 25" K7000 I've recapped it and fitted a new flyback.
I've always thought it was caused by the mains cable being bundled with the signal wires on rout to the monitor. And is on my to do list.
Not sure if your cabinet is the same, but it might be worth trying to seperate them out, as it might be a cheep quick fix.


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