Quote:
Originally Posted by Zenith26kc20
No vertical is usually the vertical IC and some capacitors connected to it. The caps cause the IC to run hot and fail. A sure sign caps are bad, once the IC is replaced is a foldover at the top of the screen.
I remember that I had to add to the heat sink to keep the IC alive. Apparently towards the end of that IC's popularity, seconds were being sold. I had the same trouble with Zenith power supply IC's when the sets with all the shorted CRTs came along. The seconds always ran HOT!
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With those Sonys, the chip is rarely bad - it's usually 1) the 22uf/50V cap off the yoke return - it's open, and ESR will be >10 ohms or so 2) Solder connections at the chip itself 3) Bad 24V or 28V source feeding the chip 4) the 10uF boost-up cap, also in the vertical area.
With lightning strike sets, the chip will usually short, taking out the 24 or 28V source - replacing the chip fixes that, but you wouldn't have a picture with the chip shorted. Two different versions - the UPC1378 and the UPC1488 - you have the earlier, and the caps are usually the culprit.
OP, have you checked the solder on the chip, and the presence of the 24-28V source feeding the chip?