WG25K7401 too bright

ELutz

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Donor 2011
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I thought I'd ask if anyone's seen this issue before I tore into it. I've got a 7401 that starts out looking fine. The longer it's on....the brighter the screen becomes....all white background and washed out....basically, like the screen pot is up too high. I can adjust it out with the screen pot/focus, but if left on....it's too bright within a couple hours. And if I turn it off for the day (after adjustment), it's too dim when turned back on. From start-up, it takes a couple hours before it starts to "brighten".....and takes 10-12 hours before it's full on bright.

I did a cap kit, swapped flyback from a good chassis, swapped neckboards from a good chassis, tube looks good on the rejuvenator...I even tried the chassis on another tube. Any ideas?

Thanks!
Edward
 
I assume the pic looks good before this happens? Have you tried swapping remotes/cables just to see if it has something to do with the brightness pot?

Also, you could check R310, but I don't think that's it. Maybe try swapping U500? Maybe R823 in the heater circuit is shorting after it heats up?
 
I assume the pic looks good before this happens? Have you tried swapping remotes/cables just to see if it has something to do with the brightness pot?

Also, you could check R310, but I don't think that's it. Maybe try swapping U500? Maybe R823 in the heater circuit is shorting after it heats up?

Yup, picture starts out looking good. The longer it's on....the brighter it gets. Once power is turned off and the monitor "cools down"....we can start the process all over again. It takes about 10 hours for the picture to go from "good" to "brightness all the way up". Thanks for the suggestions....I'll look into them.

Edward
 
Just a little bump...so far, no luck....all suggestions tested good.

Thanks!
Edward
 
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