On Thu, 17 Feb 2005 20:53:47 -0500, "Steve W. Neas" put
finger to keyboard and composed:

I have a TV with no vertical deflection, just the horizontal line
across the center.
It is a Panasonic PV-27D52, chassis KM-D2702, from 2002.

I checked the supply voltages to the vertical deflection chip
(LA7837).
Vcc (pin 1) was 23V (should be 12), and the pump-up supply voltage
(pin 8) was 28.4V (should be 24).
I removed the chip, and Vcc went to 11.8, and the pump-up V went to
29.4.

It seems to me that the IC is bad. AFAICS, there must be an internal
leak between the Vcc8 and Vcc1 supply pins. The 12V rail on Vcc1
probably supplies other ICs in the set. Hopefully Vcc1 is current
limited (by a 100 ohm series resistor?), otherwise those other ICs
would be damaged. After replacing the IC, I'd check to see that this
resistor, if it exists, has not been heat stressed.


- Franc Zabkar
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