Vizio p50hdm red flashing pixels

There is also a Vs adjustment on the y sustain board that you just installed.. Often the y sustain boards are adjusted by the factory to be calibrated to the buffer boards. Before making any adjustment on a Vo or Vs or other variable resistor mark its original position with a sharpy. There are 5 possible adjustments on the y sustain board. A specific combination of these 5 adjustments can adjust the screen for any set. Again always mark the initial position!
The 5 positions on your specific board are marked as follows:
(VSET_UP) at VR22
(VSET_DN) at VR2
(RAMP_UP) at VR51
The last two are located on a set of small perpendicularly protruding boards near the bottom of the y sustain.
The boards are listed as:
PS101 (-Vy)
PS102 (+VSC)
If I recall correctly it is one of these two adjustments on the (-Vy) or (+VSC) that will take care of the red polarization you are speaking of. These can be adjusted while the TV is running but be extremely careful of shorting components or injuring yourself.
I don't suggest making these adjustments yourself unless your are familiar with safety measures involving high voltage electronics.

Try to adjust the Vs voltage on the power supply by lower it a little bit or increase it a little bit. It will help to decrease the red pixel flashing.