LG TV not powering on

[johnc12]

hi all, i have a TV which i think is a diesel type... hehe

what i mean is that when i turn on the switch the TV doesn't turn on... after leaving it for several minutes without pushing the power button again, the TV turn on.... what could be its problem??? 1 technician tried to replace a transistor near the flyback but the problem is still there... hope anyone could help... thanks in advance..

salamat 

 

[AN920]

Often these TV's have a switching type PSU. They use a high value start-up resistor to get the PSU control circuit going. After that DC gets fed back through a diode blocking circuit to supply the control part of the PSU. Over time these resistors increase in value and have problems supplying enough DC to the control part to start the PSU quickly. Look for and measure all the 100k+ resistors (1/4-1W) that you can see in the PSU section.

Example shows a starting resistor in a Sylvania TV's PSU

View attachment 40275

 

[johnc12]

thanks a lot i'll try it...

by the way can i ask for the full schematic diagram of the TV??? i'm trying to service it now... i'll be posting the result later... maraming salamat po!!!! 

 

[audioguru2]

I got the service manual and many forums about the same problem with my Sony TV by simply entering its model number in Google.