Max said:
It's a common problem with all LCD TV sets. First, try unplugging the
display panel's backlight inverter board. It is very common for these to
fail and cause the set to revert to standby. Otherwise, it's most likely
that the PSU itself is faulty - also very common.
Examine it *very* carefully for bulged electrolytics on the secondary side.
Note that these may be 'hiding' under bits of heatsink, so look carefully.
Also, check all large and heatsink-mounted devices, for bad (lead-free !!)
joints, which is another common cause of your described symptoms. Other than
this, you're a bit 'on your own' with LCD sets. There are other possible
causes, such as bad sound output chips, but if you really do have a power
supply problem that's not one of the things described, then you will
struggle to get to the bottom of it without schematics, and an intimate
knowledge of switchmode power supplies. These LCD ones are infested with
monitoring circuitry for output voltages and over-current conditions, and
they all work on the standby supply, so if *any* unexpected condition is
detected either at startup, or during use, the standby supply is momentarily
stopped, which causes the system control micro to reset back to its 'sleep'
condition, removing the 'power on' signal to the power supply. Depending on
the set, that may then be an end to it until you try to bring it out of
standby again, or it may just keep trying on its own, causing a flashing
power light.
If you can prove which board is causing the trouble, you might want to
consider just replacing that board. PSUs and inverters for many sets, can be
found astonishlingly cheap on the 'net and e-bay sometimes.
Arfa
