power on error PDP 42V5 board.

probe2009 · Joined: 03 Jun 2009 Posts: 3

The problem of this screen is no picture and sound at all, power led on the front go on and stay green. On the power supply board the relai clicks and the led on the board go on and of every 6 times.
The relay falls back and stays in standby mode.
The protection kicks in.
I disconected the Y-sus and Z-sus boards but the fault lies in the power board.
Anyone can help me please because after spending a lot of time in checking diodes, caps and fets i don´t know where to look anymore.
Thanks a lot
Regards

probe2009 · Joined: 03 Jun 2009 Posts: 3

Hi,
I found the error, and as i suspected it was on the power-board.
It really is a stupid piece of circuit what was failing.
The fault was the discharging circuitry for the VA and VS lines.
So i replaced this to my own criteria.
Even without this circuitry it works perfectly(NOT RECOMENDABLE).LG mainly has this for servicing purposes.(well that is not completely tru but as long as you don´t switch the unit on and off repeatedly in a very short period of time nothing happens.)
As well, this discharge unit is used whenever the protection kicks in to discharge rapidly these two lines to prevent further damage.
Anyway, problem solved.

Regards