vertical ic fails over and over

I am sure you missed the capacitor that is causing the lines at the top

It is obvious you did not replace ALL the vertical circuit capacitors if you still have the lines at the top 15% of the screen.

Those lines are indicative of your problem- there is a faulty part in the vertical section which is causing the IC to fail. My first thought is electrolytic caps, but you say you've changed them all. Maybe one or more of the new capacitors was faulty. I'd check every single part in the vertical output section, check the supply rail is the correct voltage and well smoothed.

If you get desperate and have limited test equipment- change all the parts in the vertical output. There shouldn't be many, none of them will be expensive and it'll be a lot cheaper than keep buying output ICs! There could be a marginal part which is failing under stress which you might never find with normal testing procedures.

Don't forget to reflow all the solder joints in the vertical section as a matter of course, and while you're at it do the same to the power supply. Check any components on the yoke are OK and the correct value.

Incidentally, has the vertical output gone altogether, ie seriously squashed picture or horizontal line? If not, and the only symptoms are white lines in the top of the picture then chances are the IC is fine, some passive component is causing the problem. Again- capacitors are the likely culprit. Forget that you already changed them, electrolytics are notoriously unreliable and could easily have failed again.

Dave

Also, in addition to the other tips you have been given, if it doesn't have one, add a heat sink to the IC. Are the replacement IC's the same package material as the original? For example, some original IC's may be ceramic while the replacement may be plastic. There are obvious heat transfer property differences between the packages. Don't forget to use heat transfer compound between the heat sink and IC. Just my 2¢.

Thank you all, you were all right. It seems I forgot a capacitor (or two). Since I don't have the schematics and couldn't figure exactly where the vertical circuit starts and where it ends, I've tried to replace some more capacitors in the nearby (along with the vertical IC again) by following the connections on the board, and it seems I got it right. The tv works, but more important - the top white lines are gone, so I hope this time the IC won't burn so quickly.

Thanks again.

glue a heat sink onto it for good measure. Mark

What model? There are some TVs (there was at least one Philips model) that require some circuit modifications to prevent this.

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