i checked from the manual what ever mentioned
Firing pulse cable to relevant thyristor is interrupted
♦ Ribbon cable X101 or X102 is incorrectly inserted or interrupted
♦ Defective electronics or gating board
♦ Internal interruption in gating cable in thyristor module
but all the above issues not there
i checked it what else shall i open the thyristor and verify?
any other possible reason?
thanx in advance