Convergence IC STK392-110 vs STK392-110T

Aug 12, 2006

- So I went ahead and bought a pair of IC STK 392-110s.
After much strugle, I managed to desolder and take the chips out and put a new pair in and soldered them back.
Result? a little better, but not watchable yet.
With the heatsinks properly attached to the chips, the TV does not auto turn off anymore. The image stopped shaking, I can see the image better, but the red alignment is still not lined up. I went to the convergence set up screen and tried to align the Red and Blue crosses on the Green. There are 10 positions to converge, the center screen and the 9 positions on the edges of the screen. For the center position,the Blue cross works perfectly, but the Red vertical line seems to be longer. i.e. I could see the top and the bottom of the cross red. For the 9 positions at the edge of the screen, the left and right of the screen align well. But the top and bottom ones do not. The Blue ones align fine. I tried to move the Red, but while I could move it, I could not get it aligned. It stopped short at below or above the green cross.

Can this be fixed in the Service Mode or is there another chip not working?

Any suggestion will be greatly appreciated.
Thanks,
/Dara

Aug 22, 2006

- I finally decided to go ahead and replaced the two STK392-110s ICs. The TV worked fine after I replaced them. By the way, I found the chips are unusually hot and the heatsink must be attached properly or the ICs will overheat and causes the TV to shut down again. So after 2 weeks of enjoyment, the TV again started to shut down after 2-3 hours of continuous use, but the picture was still good. A few days later, the picture again showed convergence problem and the TV shuts down after 3 minutes. So it looks like the ICs were fried again. So I think techman is right about something else died. It seems more than the ICs that were burned. Could it be the power regulator, the STR***** chip, or some capacitors got fried too?

I appreciate any help.

Thanks!

By the way, on the 55H70, there is an easy way to remove the STK392-110's. You don't need to remove the PCB, connectors, cable or anything like that. The power PCB and the control PCB are screwed onto a plastic frame. The plastic frame then is fastened to the TV wood by 3 black wood screws (it might be less or more on different model). You remove these 3 screws then loosen the cables from the cable ties and holder then slowly pull the entire board out. Then you can stand the entire board in a vertical position where you can desolder and solder the ICs. Taking the board out to this position takes 5 minutes. Soldering the ICs back take a little more care since you need to do it vertically and the solder tends to drop down a bit.