Prima PS-42D8 B Service Manual page 24

a. If it's a vertical bright line of other colors, then the problem lies with COF or the screen.
b. If it's an entire vertical block of other colors, then first check to see if the connection socket
between COF and logice BUFFER has problem. If no problem, check if the connection socket
between the logic BUFFER and the logic board is normal. If it's normal, then replace the logic
BUFFER. If the problem still remains after the replacement, then replace the logic board. Finally if
the problem is still there, then the problem lies with COF.
6.There appear on the screen abnormal bright spots or blocks that are different from what's described
above:
a. Check if the connection socket between COF and logic BUFFER board has been well plugged.
b. Replace the logic BUFFER board. If it's not solved then replace logic board. If the problem still
remains, then it's the problem with COF.
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