no screen with sound on my tv daewoo dth2881-100D chassis cp-830F

[mooswief]

hi there, when the tv runs the screen is getting black with sound after  a couple of hours.
i resolderd the prints but this doesn't solve the problem.
when the screen is getting black the sound is still ok, but when i feel on the outside of the screen
it looks like if there is no high voltage anymore.
plse help , i'am lost.
tks in adv