LG 50PK550 no picture but sound

[TheDCE]

Hi,

a friend of mine brought me his LG tv which has no picture anymore.
In his words, the tv went from working to blank without any prior signs of error.

When powered up, there is no glow on the pannel, but the remote and sound are working.

So i opened it up and started to follow the guides i found here.
The fuses seem ok, and the resistors at the top right corner of the PSU are all at 10 Ohms.

Voltages are:

Vs on P812: 203,1 volts
Vs on P811: 202,9 volts

Va on P812: 60,1 volts
Va on P811: not connected

5 Volts on P812: 5,04 volts
5 Volts on P811: 5,09 volts

VSC with Y-Drive boards connected: 0,4 jumping to about 2,6 volts
VSC with Y-Drive boards unplugged: 150,6 volts

-Vy with Y-Drive boards connected: -4,7 jumping to -30 volts
-Vy with Y-Drive boards unplugged: -189,5 volts

VZB: 114,7 volts

LED on mainboard is blinking

The strange thing is, when the tv is powered up with the two Y-Drive boards unplugged, VSC and -Vy voltages are stable and the pannel shows a picture like this:


Does anyone know, what to do here and how to investigate this problem further?

Many thanks in advance .. Holger

P.S. Here is a link to higher resolution photos, in case the attached ones are not sufficient -> https://picasaweb.google.com/1042620...eat=directlink