Looking for advice on the repairing of a hitachi commercial plasma monitor cmd 4201 currently cycling off after power up.Shot gun repair effort so far ,just replacing suspect board x and y substain s. Power supply board .I have repaired it several times before luckily. Want to do a more complete evaluation of my problem. The power supply I assume is cycling because of I believe that the Y substain is bad. Can I test the power supply board to rule out,problems on it. Should the power supply supply vs va for the substain boards with them unplugged,. Will I get the voltages before it cycles off or not. I have a trouble shooting flow chart that suggests a sequence of tests for narrowing down the problem,. So is anybody familiar with these monitors,it does not have a tuner. Thanks joe