WG 25K7401 Contrast bleeding issues

[DynamiteSJ]

Hi...

I've been workin on this monitor (been awhile since i got around to it) i installed a new flyback and cap kit. It looks a whole lot better than what it did before but i am still having troubles with having a dark screen. I can make it have the colors and brightness be what it needs to be but when its at that setting i get major bleed of colors... mostly white and yellow. Any contrast that i give it... it bleeds... doesnt matter how much.

On the cap kit... all caps came included except the big one.... could that cause this issue... or is there another adjustment i should be doing? I only adjusted the 2 knobs on the flyback and on the monitor control panel.

[lilshawn]

try adjusting the color cut off until an acceptable screen contrast doesn't bleed out anymore.

[SirPeale]

For giggles, check R811 on the main board and see if it's gone open.

[DynamiteSJ]

hmmm... where do you adjust color cut off? On the control panel? Contrast must be all the way down for no bleed... and little contrast givin... it bleeds... I'll try to take a pic or make a quick vid of it tomorrow.

and...

what am i exactly looking for in R811?

[SirPeale]

what am i exactly looking for in R811?

To see if it's gone open.  You'll need a multimeter, and you'll need to unsolder one end of it to get a proper reading.

[DynamiteSJ]

where can i buy a R811? I'll just replace it and go from there

[SirPeale]

where can i buy a R811? I'll just replace it and go from there

It's a 1/2 watt, 100K ohm resistor.  Don't just replace it...test it!  If it's fine then that's not your issue.

[lilshawn]

sorry on the 7400 the pots are labeled "x bias" not cutoff replace x with r,g,b it's on the neckboard attached to the tube.

best way to adjust is with a gradient square pattern and make it so you can see all the squares and not just one solid bar.

[DynamiteSJ]

I looked up the monitor schematics on the wells garner page and it showed up... 75K 1/2W resistor.. will that make a difference from the 100k you mentioned?

[DynamiteSJ]

thank lilshawn on that info.. i check tho settings later when i get home

[DynamiteSJ]

well... i adjusted all the pots on the neck in the display settings menu (Tekken 3) and the display got better... had to play with the settings for a while. I believe the picture could be a little better but i am gonna assume its the tube since everything else seems to be fine.

[SirPeale]

I looked up the monitor schematics on the wells garner page and it showed up... 75K 1/2W resistor.. will that make a difference from the 100k you mentioned?

Interesting, the 7400 may be different from the 7500.  Check what is actually on the board and see what the value is.

Either way, if it's open, replace it.

[southmonitor]

This is a common problem for those K7400 and more often than not the Tube is the problem. Many are old already. Anyway there is a subcontrast pot on the main board and you can also play with the bias and gain pots on the neck board to try to improve the image. If you have replaced the bad caps already there is not much else you can do in the Chassis and the tube is likely to be the problem.