WG 19K7901 Monitor showing overpowering red with horizontal lines

Bullwinkle

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WG 19K7901 Monitor showing overpowering red with horizontal lines

I have this monitor in my Thunderblade cabaret. It comes up with a hideous red screen with horizontal lines. The horizontal lines head south towards the left of the screen. I have hooked the thunderblade cab up to my WG 25K7191 and the game runs fine. I have since recapped this monitor (although there is one cap I was unable to replace as I had nothing even close to resembling it ; "560uf 200v" i believe (circled in pic below)

mainpcb.jpg


and here's the red screen issue

rsod.jpg


Any suggestions on where to start? It did flick over to correct colors for about 30 seconds twice, but then went back to this. Thought it might have been a failing cap so I replaced the caps to eliminate that as a possibility (unless of course its the one I didn't replace).

Thanks,

Tom
 
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Open up that cardboard piece on the neckboard and look for bad solder joints - bet you'll find a few. Also try wiggling the red controls on the neckboard (very carefully/lightly) to see if it changes - could be a bad pot.

PS - The big cap is the filter cap and usually not part of cap kits. Its usually OK unless you get a lot of waviness in the picture.
 
Orion3311, I messed with the red drive and red cutoff pots quite a bit..no change though. I'll take the cardboard off the neckboard and see whats up there.

Thanks
 
If you get a screen that "flickers" between good and bad, that is usually an indication of:

a) cold solder, either on the neckboard or video input pins

b) a bad pot - perhaps the red pot is going bad and is flickering between normal and "all the way up"

c) an internal short in the tube. a rejuvenator can fix it.


I guess it's also possible that it could be an issue with the output from the board, but you'd have to hook it up to another monitor to be sure...
 
Looks like an internal short on the red grid in the CRT.
Try gently but firmly rapping the neck with the rubber handle of a screwdriver to see if there is any arcing in the neck of the CRT.
Use care not to break your convergence magnets.
You may even get lucky and knock away the short and fix your tube.

Don't worry about that cap.... it's not your problem.
 
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OK, I pulled the neckboard off and took a quick look at the components (especially the red pots). I couldn't see anything that would indicate a cold joint, but I know its not always visible so I resoldered both the drive and cutoff of all the pots and it seems to have done the trick!

Thank you everyone for the great tips. Just learning monitors and it took me 3 weeks just to get up the nerve to discharge one :) Better at it now though.
 
You know, if you turn that on its side and change the problem color to green, it seems to be the same issue my pacman monitor is having; overwhelming prevalence of one color, and slightly diagonal lines that get closer and closer together. I think I'll try the pots on mine, too.

Thank you for posting your solution rather than just moving on; solutions are always appreciated!
 
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