HP Probook 450 G8 mobo DAX8QAMB8D0 REV D dead

I found U6202 shorted, after removed short is fixed

Both bios chip seems to replaced or flashed

PU 8601 is warm
PU 8601 voltages

Pin 1 = 19V (must be 5V)
Pin 5 = 19V
Pin 6 = 1,6V
Pin 7 = 0,2V
Pin 8 = 2V
Pin 9 = 5V

Voltage coils

Only PL 8604 = 2V

Resistance Coils
PL8604 = 170 Ω
PL 8601 = 15,6 K Ω
PL9200 = 1,3 K Ω
PL8701 = 334Ω
PL8202 = 5,7KΩ

PL 9101 = 76Ω
PL 8903 = 23Ω
PL 8902 = 23Ω

Now I found a short to ground on pin 9 of PU9500
After removing PU9500 short is still there.
But without PU9500 I got 3,3V on PL8601 and led on the motherboard blinking

PL8604 = 170 Ω resistance too low. Do short circuit test.
Measure the voltages on all pins of U5401.

Short circuit makes PU9500 quite hot.
After removing PU9500 resistance to ground on PL8604 is 170 ohm and current absorption is 200 mA
Nothing is hot

U5401 voltage of 3,3V pin 3’and pin 5 others pin 0V

Was the resistance to ground on PL8 measured after some time to allow the capacitors to discharge?

I measured again resistance is 190 ohm
Problem is short on +3V_DEEP_SUS pin 9 of PU9500
Short circuit on that pin without IC, U4700 becoming quite hot

Unsolder the KBC and check if the resistance increases.
If it increases the KBC must be replaced.

After removing KBC problem is the same all around KBC is hot but not a single component
Short circuit on pin 9 of U9500

Unsolder R1616 and check which side you have low resistance on.
Measure the resistance to ground on pin 1 of U1600.

I found the issue
As I wrote both bios chip seems to replaced and I found short on pin 8.
The picture shows missing isolation too near on pin 9
Short now has been removed
I have to solder all missing components to get a result

Resolder everything that was disconnected and test if it works.

I soldered all components
I got 3,3V and 1,8V
Problem is 1,9V instead of 5V on coil PL8604
PU8601 damaged?

Measure the resistance to ground of PL8604.
easure the voltages on pins 1, 4, 5, 6, 9, 10, 13 of PU8601.

PL8604= 207 ohm

PU8601
Pin 1=19V
Pin 4= 0V
Pin 5= 19V
Pin 6 = 1,8V
Pin 9 = 5V
Pin 10 = 2,6V
Pin 13= 1,95V

PL8604= 207 ohm

Resistance too low.
Do the test described here on PL8604 (explained at the end of lesson 3):
post5699.html#p5699

As I supposed PU 8601 was damaged.
Replacing now I got 5,1V on PL 8604 and 3,3V of +3V_DEEP_SUS
But motherboard doesn’t power on
I unsoldered KBC, can be it damaged?
Also EC and Main bios was replaced by the customer damaging and making a short on pin 8 (solved)

Does the LED next to the DC socket glow white when you plug the charger?

No led on the socket and no led on the motherboard

Remember that was a short to ground on pin 8 of main bios chip

Now do you have voltages on all the coils?

Measure the voltages to ground on listed pins (with the KBC chip soldered of course):
- On pin 1 of resistor R4740.
- On pin 2 of resistor R4725.
- On pin 1 of capacitors C4702, C4715.
- On pin 2 of capacitors C4705, C4707, C4710.
- On pin 1 of transistor Q7502.
- On pin 3 of transistors PQ8011, Q7507, Q7508.
- On pins 5, 11, 12 of charger chip PU8200.
- On pins 6, 7 of chip U6203.

Transistors PQ8011, Q7502, Q7507, Q7508 pinout:

R4740 = 3,3V
R4725 = 1,8V
C4702 = 3,25V
C4715 = 3,3V
C4705 = 3,3V
C4707 = 1,19V
C4710 = 0,8V
Q7502 = 3,2V
PQ8011 = 3,3V
Q7507 = 3,24V
Q7508 = 3,24V
PU8200 pin 5 = 3,3V
pin 11 = 3,3V
pin 12 = 3,3V
U6203 pin 6 = 0V
pin 7 = 0V

Sorry I forgot to replace U6202 now motherboard led blinking amber but DC connector led is still off.

Also I checked missing 1,2V RAM voltage