(1) check the control card has no pulse output and check the line and the driver is in good contact,
the key is not failure.
(2) please check the control card back to zero switch and control card control port has no pulse
output.
(3) check whether the return to zero has been bad.
(4) check the direction of the control card control port signal and check whether the line is in good
contact with the driver
(5) check the cable port on the panel to the control card Display port link is open
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