820-00239-A , turn on, no image or backlight

[rui4892]

hello forum. i need help how to solve this problem.

turn on, no image or backlight

PPVCC S0 CPU 0V , after 3 seconds 1.04V stable for 10 seconds , then 0V

L7430 4 ohm 0V , 0.7V after 14 seconds and remains stable
L7520 4 ohm 0V , 0.7V after 14 seconds and remains stable
L7410 4 ohm 0V , 0.7V after 14 seconds and remains stable
L7210 7 ohm 0V , after 3 seconds 1.04V steady for 10 seconds , then 0V
L7220 7 ohm 0V , after 3 seconds 1.04V steady for 10 seconds , then 0V
L7270 12 ohm 0V, after 4 seconds 1.05V, after 11 sec 0.875V and remains stable
L8000 205 ohm 0V, after 4 seconds 1.02V and remains stable
L8050 140 ohm 0V, after 4 seconds 1.01V and remains stable
L7900 300 ohm 0V, after 4 seconds 1.20V and remains stable
L7960 70 ohm 0V, after 4 seconds 0.95V and remains stable
L7700 after 4 seconds 1.05V and remains stable
L7030 after 4 seconds 13V and remains stable
L8410 always 0V
L3500 always 0V
L7660 always 3.3V
LB700 always 0V
L9400 always 2.7V

plate consumption

0W , after 3 seconds 17W with fluctuations up to 20W , after 10 seconds it has a consumption of 9.5W

historic:
the display was replaced about a few months ago due to it being broken.
small evidence of corrosion on the Q4201 has now been re-soldered and cleaned.

thanks.

[mon2]

Re: 820-00239-A , turn on, no image or backlight

Is the unit stable without the display ?

Start with checking the voltage of PPBUS_G3H = F7000 (fuse), pin # 2. What is the voltage here ? Is it steady ON upon power up ?

[rui4892]

Re: 820-00239-A , turn on, no image or backlight

good morning, first of all my thanks for your prompt help.

without the display the voltage on pin 2 of the F7000 is 13.0V and stable.

initially 0V, after about 4 seconds it is stable at 13.0V.

thanks.