mits VS-50805 Green shadowing after power interruption

[bwinters]

lcaillo

I have a mits VS-50805. About a week ago a lightning storm caused power to cycle to my set. Ever since, I have this green(only green) shadow on the right side of everything on the screen and from time to time the entire picture turns a light green color. If I bring up a menu with letters on the screen, the green colors smears straight to the right of the letters. I inspected my convergence ic's and didn't see any stress around the solder joints. I cleaned the ic's and heat sink and re-applied new thermal compound. I was going to order and replace the ic's but I don't have the "hourglass effect" so many talk about with bad ic's. Can the ic's still be my problem or do you think I have something else going on?

Thanks,

B

[lcaillo]

Your duplicate post in the other thread has been deleted. There is no need to post twice.

This sounds like it is not convergence. If the green makes a flare off to the right, it is usually a G2 or bias voltage problem. You could have a bad focus/G2 block, a bad tube, a resistor that has changed values, a bad video output amp or any number of other issues. This one needs some troubleshooting by an experienced tech.

You didn't play with the screen (G2) controls did you?

[bwinters]

No, I don't know what the G2 screen controls are. I was home for lunch and my picture looks perfect again, no green haze or shadows. My wife said after about 3 hrs. with the set being on, the picture cleared up and it was good for 2-3 hours. So, I powered it off again and let it set, unplugged for 30 min's and restarted. The picture was good for about 3 min's then the green haze and shadows started again. Any suggestions as to what solder joints to resolder, or is that a possibility. If it's on the green crt drive circuit, i'll leave it to the pro's. Thanks for your help....

[lcaillo]

Not likely, but you could check the ones on the grounds on the green CRT board. Could be a problem there or with the connector at the base of the CRT.

Look for coolant leaks as well. That is a real possibility on these sets.

[bwinters]

Do you have a picture of what the coolant looks like when it leaks on a power board? There is white/yellowish foam looking stuff on a couple of places on the board. It is hard to the touch but I thought it looked like it was put there to protect the components it covers.

[lcaillo]

The coolant in these types of sets is a clear solution of ethylene glycol and glycerine. Itwould look like a wet spot on a board, and if it has been there any length of time will absorb water from the air and start to corrode leads leaving a messy green and black goo on the parts and traces. If you see it, do not run the set at all and map the coordinates of the board that are affected as carfully as possible then get back to me for instructions. It is critical to handle the problem correctly or you can make it impossible to repair reliably.

Most likely you have something wrong related to CRT bias or setup.