[SOLVED]820-2850 no backlight

[dukefawks]

No idea, 2.5V seems low. We can talk about this all day but you need to swap the LP8545 and check all resistors.

 

[MDY]

Will replace LP8545 again and will compare with another board I have here for parts.
It is possible to test screen connecting 30V to VLED directly? Will turn on the leds or it is no enought? This way also I can check if leds turn on at 27,28 or 29V

 

[dukefawks]

Negative to LED return lines and positive to the BKL Vout. LEDS should light at about 30V. But do this with a variable power supply and go up from 20V till they light up.

 

[MDY]

Sorry, you mean I have to put all 6 return lines to negative? And PPVOUT_S0_LCDBKLT to power supply. 20-30V

 

[dukefawks]

Why do you even want to mess with this? This is not going to fix the board. I gave you the correct voltages from the board.

 

[MDY]

Finally I got this board working. Resume: I found LP8545 damage and no backlight. After I replaced this IC with new one I got only 25V and no backlight. I replaced it again with new one same provider and again only 25V and no backlight. I replaced it again and the same. Always check carrefuly how this chip is solder and I solder this chip perfectly.

Then I took this chip from my board for parts and now backlight works and I have 33V

New chip from SEE-IC I got is written on it: VM08AD 45-EXTF. This chip doesnot work for me. I got only 25V with this chip. Could be fake chip? Or not exact part number they sent to me?

 

[dukefawks]

These chips have en EEPROM inside. Maybe they are programmed for something. A blank default EEPROM normally works.

 

[MDY]

Never find a not working new chip?

 

[dukefawks]

I don't buy these new chips, enough donor boards in the pile.