I have a samsung plasma that clicks but won't turn on. After disconnecting and then alternately reconnecting the different boards only the X board causes the clicking sound and no turn on. Is it bad

Probably power supply failure

Sustain board fault. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/

What do you mean by clicks? Plasma televisions are hot cathode ray, there is thermal expansion that takes place due to heat.

The main board is causing the problem

ORIGINAL SAMSUNG BN44-00445A BN4400445A POWER SUPPLY FOR PN59D550C1FXZA PN64D550C1FXZA
Original Samsung BN44 00445A BN4400445A Power Supply for PN59D550C1FXZA...

Hi,
check the video
Samsung plasma tv S50hw yb05 vertical colored lines diagnose fix su board...
www.electro-medical.blogspot.com

Here's is what you need to look for when describing a problem for troubleshooting purposes:

0) What model is the TV (you've covered that)

1) Does the TV respond to command to turn on?
(yes - continue; no - 70% bad power, 30% bad main board)

2) Once it responds (clicks), does a front LED or other indication show that it turns on? It's OK if there's no display.

(that can be model specific and is not certain indication for anything until known what is specific for the model)

3) If such an indication comes up does it remain on until you act or does it go off by itself?
(Stays on - power supply likely good; turns off - power supply *may* be good, but not certain)

4) If the power indication stays on by itself can you make it go off by pressing the power button or do you have to disconnect from AC power?
(responds to power off - 90% power supply likely OK and 90% OK main board; does not respond to power off - 90% bad main board)

Here is a link for test/repair of the power supply of your TV, hope it would help:

http://www.coppelltvrepair.com/p/895/samsung-pn58a550s1fxza-power-supply-repair-service-for-dead-or-clicking-on-and-off-problem

& blinks is sc or,sd or ,su board or all 3. Disconnect the ac cord. remove the back cover. on the left are 2 thin boards with flat cables that connect to the panel. these 2 boards are the SD and SU boards. They are connected to a board to the right. This the SC board or Y sustain board. Disconnect the 2 wie plug that connects this SC board to the power board in the middle. Examine the sqauare ics on the SC and SU boards on the rt side. Look for a pit or burn mark on one of the ics. If you see one then this board is bad. Disconnect this board from the SC board remove connectors on the rt and also remove the all the screws on this board. It should now be hanging free only by the flat cables on the rt. reconnect the 2 wire cable from the SC board to the power board. Plug in the set and power on. If set turns on the that board needs replaced. You will see 1/2 of picture. If still won,t turn on then disconnect the ac cord and the 2 wire conn from power board to SC board. disconnect the other board on the left letting it hang free. re connect SC to power board,plug ac cord in and turn on. If set now will turn on then Replace that board. If stiil won/t turn replace the SC board.

Says bad 15V bad. To check on D board.

Could be power board. Check for swollen capacitors . If ok next check buffer boards for burnt ic. With set unplugged unplug power board from sustain boards. Plug back in and see if it turns on. Unplug again and disconnect buffer boards from sus board plug power supply back into sus to see if it powers on. If it does then buffer boards bad. Isolate upper and lower to Determine which one is bad. Just always remember to disconnect power board from sus boards when disconnecting panel to buffers. Power supply stores a lot of energy and will burn these connectors while reconnecting them.