One technique is to open the tv up and with it switched ON start tapping the back of the PCB's with the plastic end of a big screwdriver. Where the picture comes good then you've found the area where the dry joint is. Re-solder the joint and it should be OK.
BE VERY CAREFUL!!!! Inside a tv there are voltages in excess of 25,000 volts and even if the TV has been switched off for a couple of weeks then it is still dangerous! Basically do not touch anything except with the plastic end of the screwdriver.
If you are not sure then pay somebody to do it. Better that than end up giving yourself a very nasty shock.
C, June 2004
