Prima PS-42T8 Service Manual page 24

yes then replace Y BUFFER (upper, lower) in respect to the upper, lower part of the dark line on the
screen.
2.3 There appear on the screen one or several horizontal lines that are much brighter than the
remaining horizontal lines at the edge:
Check if the socket between Y driving board and Y BUFFER is plugged well. If not, plug it well. If
yes then replace Y BUFFER (upper, lower) in respect to the upper, lower part of the dark line on the
screen.
4.There appear on the screen one vertical unlit line or a vertical entirely unlit block
a. If it's one vertical unlit line, then COF has problem.
b. If it's a vertical entirely unlit block, then first check if the connection socket between COF and
logic BUFFER has problem. If not, check if the connection sockets between the logic BUFFER and
the logic board is normal. If yes, replace the logic BUFFER. Finally, if the problem still remains when
the replacement is over, then replace the logic board.
5.There appears on the screen a mono color signal and one or several vertical bright lines of other
colors:
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 logic 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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