LG 32LN540B power on problem

[stomanata]

Hi,
The power board is EAX64905001 (2.7), over
internet i found wiring for (2.4).
May be the whole problem is that
i have 3.13V instead 3.5V. When i power up tv
the red led light up for ~10secs, then power off
for 3-4sec, and again power on, power of, etc.
In version 2.4 output 3.5V came from main transformer - D203-
C201- LB201- C209-C210.
But in my case (2.7) 3.5V came from IC202 (NR891D).
In hid datasheet there is only info that from output must
have 5kohm resistor to FB to produce 3.3V but i can`t find
what control and how to calculate output voltage.
I change both capacitor near to LB201, but this did not change
output voltage of 3.5V line - it stay 3.13V.
What other to check?

[nomoresonys]

Re: LG 32LN540B power on problem

Pictures?: https://www.badcaps.net/forum/showthread.php?t=39740

[stomanata]

Re: LG 32LN540B power on problem

Pictures?: https://www.badcaps.net/forum/showthread.php?t=39740

Thanks. I upload pdf that i have for 2.4

[nomoresonys]

Re: LG 32LN540B power on problem

If you haven't already, unhook cable from powerboard to mainboard and test the pins on powerboard, see what voltages you get and if they are steady.

[stomanata]

Re: LG 32LN540B power on problem

If you haven't already, unhook cable from powerboard to mainboard and test the pins on powerboard, see what voltages you get and if they are steady.

It is better - 3.45V
So, may be fault mainboard?

[nomoresonys]

Re: LG 32LN540B power on problem

seems to be dragging it down a little, try testing the powerboard as stand alone, with tv unplugged from power, unhook cable from powerboard to mainboard on mainboard side, I jump it thru the end of connector by tracing the wires from the powerbord side to the cable end, take three 1k ohm resistors and jump from PWR-ON TO 3.5, DRV-ON TO 3.5 and P-DIM to 3.5, plug power cord in, see if backlights come on and stay on and the other voltages come up to expected levels.

[stomanata]

Re: LG 32LN540B power on problem

seems to be dragging it down a little, try testing the powerboard as stand alone, with tv unplugged from power, unhook cable from powerboard to mainboard on mainboard side, I jump it thru the end of connector by tracing the wires from the powerbord side to the cable end, take three 1k ohm resistors and jump from PWR-ON TO 3.5, DRV-ON TO 3.5 and P-DIM to 3.5, plug power cord in, see if backlights come on and stay on and the other voltages come up to expected levels.

There is backligh, voltage is 66V and other voltages seems to be OK

[nomoresonys]

Re: LG 32LN540B power on problem

Seems like a mainboard issue then.

[stomanata]

Re: LG 32LN540B power on problem

Seems like a mainboard issue then.

May be yes. Thanks for all your support