Hello all, I am working on a Samsung HP-T5064 50" flat screen plasma with a dark/blank screen and no picture. I have the issue narrowed down to the Ysus/Ymain board. The LED indicator on the board lights up indicating a problem. My Vs is good at 204V but VScan voltage at the test point on the board is about exactly half of what it should be, proper voltage should be -190V according to the label and I am getting -97V. The board# is LJ92-01490A/LJ41-05120A. I also measured voltages at the following test points:

SIN_2 should be 0V
OC2_C_2 should be 3V
OC1_ODD_2 should be 3.5V
LE_2 should be 0V
OC1_EVEN_2 should be 3.5V
CLK_2 should be 1.3V

I have readings of 37V on every pin listed above.
I removed and checked all the FETs (14 of them I think?) and 2 diodes from the heatsinks and they all tested good. I checked all of the caps and had 2 that were questionable so I replaced them. I also replaced both B13NK60Z transistors near the test points b/c they were surface mount and since I had them off to test I just replaced them with new ones. The problem doesn't change with the buffers disconnected and both Y buffers test good. I hope that someone can help me narrow this down to the cause and point me in the right direction. I'm not sure what ckts/components convert Vs to VScan. Thanks to all in advance.

 

To simplify the concern, does anyone have a suggestion of what may be causing the Vsc voltage to be half, disregarding the other measurements?