HP Pavilion 15-AK112NL Power On but no Video (MAIN DAX1PDMB8E0)

Good afternoon friends of the forum. This laptop enters me with the following defect. Pressing power on, the LED lights up, the fan turns on but does not go on the screen. Also tested with external screen but nothing. I only notice that the caps lock flashes 5 times. Tried to change ram, reprogram bios. I found no corrosion, Checking the voltages in the coils are all present. Thanks

many thanks matic.
So without turning on, I measure 10mA
when I do power on I measure 0.74A

Try to turn on the machine without RAM memory connected. Are there any changes in operation of the machine in this case?

No same synthom, caps lock blink

Also measure the power consumption of the board, when the machine is turned on without RAM memory connected.

0,73A

Make sure, if you tested the board with a low voltage DDR3L RAM.

yes, tried other ddr3L but nothing

Do you have a DDR3 RAM slot LED tester? If so, test both RAM slots.

yes, only the reset led lights up strongly, the other leds are poorly lit, tested in both slot

reflowed pch but nothing. Contacted customer for replace pch . Very thank's matic for your help.

if the customer accepts the quote, replace the pch and I'll let you know if it worked

Hi Matic, I recently soldered the new pch. Unfortunately it remains with the same defect, fan that starts at the latest after a few seconds, black screen and flashing of the caps lock, flashes 5 times and then 3 fast flashes

Thank's Matic
Pin 1 3,34v
Pin 2 3,34v
pin 3 3,34v
pin 4 gnd
pin 5 0v
pin 6 0v
pin 7 3,34v
pin 8 3,34v

Yes
Matic i was thinking, could it be a rom problem inside the kbc? I ordered the svod so in case the kbc is reprogrammed

Hi Matic, I'll update you on this laptop. I got the svod, I reprogram the kbc through the dump downloaded on this site, the same defect remains, caps lock flashing. I buy a new kbc, soldered it, wait 5 minutes witch ac adapter connected and give the power on, the machine starts but gives the same defect, caps lock flashing and no video in the screen. I reprogram the kbc always through the dump download from this site but same problem. What could I check now? Thank you

Between pin 1 of BIOS chip and pin 101 of KBC chip.

15ohm

Between pin 2 of BIOS chip and pin 103 of KBC chip

15ohm

Between pin 5 of BIOS chip and pin 102 of KBC chip

15ohm

Between pin 6 of BIOS chip and pin 105 of KBC chip

15ohm

Check the highlighted 4 resistors (pictures below).
All four must have a value of 15Ω.

all four resistor is ok ( 15 ohm)