Red color missing on two monitors

Drewdah

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So I have two different cabinets in the garage that have nearly identical monitors, one a Konami 4 player cabinet and the other a dynamo z-back.

Both monitors "work" for the most part, but I have a persistent problem with them both where the Red color will flicker and disappear from the picture after the cabinet is moved or bumped. In both cases, jiggling or slightly tugging on the ribbon cable going to the monitor neckboard makes the red color come back, but it doesn't stay when playing.

Anyone have any idea how to fix this? I read through the stickies in this forum and didn't see anything about my specific problem.

Here's the serial numbers I have for each monitor to try and identify them. I believe them both to be 25" k7191 variants, but I've got some Zenith serial numbers on there too.

Dynamo Cab:
Zenith R-A63ADG25X
WG846995

Konami Cab:
Zenith R-A63ADG25X
Y49K7191-000
054A7191-007
 
You have a solder problem. It could be where the video comes into the neck board, a connector in that line or the components that work with the red signal on the neck board. Look at the pots and transistor for cold solder. If all the solder is good it could be the tube socket but it's typically cold solder.
 
Once I didn't have the anode cap installed correctley on the tube and I couldn't get red on my Go7. Not saying that's it but might be something to check into. Discharge with caution if this is the case.

This lead to me seeing the biggest zap I've seen with my own eyes when I went to discharge the tube. Scary!
 
Once I had the same issue with a monitor. It was tracked down to a dirty pot on the neck board.. A bit of PCB cleaner (compressed fluid through the thin red straw) directed at the pot coils did the trick.

Cheers
Darryl
 
As stated above it you should reflow the solder on the header pins on the chassis. If that doesn't work then check your color drive transistors. If they are good check the color pots.

My guess is these are both K7000 monitors. If so, one of these three things will fix it assuming the tubes are good.
 
Check the connector where the video connects to the monitor chassis. R-G-B-Blk-space-White. Wiggle that while the game is on and see if the red comes in and out. This is where 80% of the cold solder joints occur. If not there, then it is probably on the neckboard at the larger transistors. Find the red adjustment knobs and follow them to the transistor and resolder the joints on the neckboard. (Do this test with the power off by the way) Reinstall chassis and try again.

Since you mentioned that it happens when you tug on the cable to the neckboard, resolder each of the points where the cable connects to the neckboard.

Good luck
 
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