Fujitsu Lifebook U729

[dhs6512]

Hello. Notebook Fujitsu Lifebook U729, motherboard CP761853-X3. Please help to recognize 5-leg component. Marking: high line "Dot K", middle line "A7", low line 72. Near edp connector. Photos attached. thank you.

[dhs6512]

device year 2019

[mon2]

There is a solder ball shorting pins 2-3 in the posted picture.

[dhs6512]

Thank you. Yes, I know, I want to replace this component, but cannot find what exactly it is.

[mon2]

Review where the circled via ends up on the LVDS connector. Is it mated with pins 29 & 30 on the LVDS connector?

It appears to be a power switch. Attached is a partial schematic from other Lifebook units. Confirm the pinout and check if it matches your board.

If it does, consider to use part # G5243AT11U

[dhs6512]

The circled via hole is GND. Removed IC and measured resistance to GND at all five contacts, photo attached. Nothing from them have direct connection to lvds connector. Seems not good at leg 5.

[mon2]

Ok.

Pin # 2 = ground. This is a match.

Meter on pin # 1 PCB pad; other meter probe onto pin # 30 on the display connector. Meter in resistance mode (not diode). What is the measurement?

Repeat with testing on pin # 29 on the display connector. What is the measurement?

[dhs6512]

If we consider that pin#1 is left of the lcd connector ( there is no marking on the PCB at all), then pin #1 IC – pin #1 lcd conn mohms, pin #1 IC – pin #2 lcd conn mohms, pin #1 IC – pin #29 lcd conn (GND) 9,69kohm, pin #1 IC – pin #30 lcd conn mohms.
I think this lcd connector has big difference from your posted schematics above. I think this connector has backlight power (2, 3, 4, 5), GND (9, 10, 11, 12 ,14, 15, 20, 23, 26, 29), LCDVDD (17, 18), differential pairs 21+22, 24+25, 27+28

[mon2]

Do pins 17 & 18 of the lcd reach this sot23-5 device?

If yes, which pin?

[dhs6512]

No, #1, 2, 3, 5 of sot23-5 1,8mohm to #17, 18 lcd conn, #4 of sot23-5 2,8mohm to #17, 18 lcd conn

[mon2]

Use the meter in diode mode. This will tone beep when probes are shorted. No power to the board. Proceed to mate one pin to this mystery chip. Other probe to other nearby parts. Trace out the fan out of this chip for a review.

[dhs6512]

Photo attached: #2 is GND, #1, #3, #4 have not links to external parts, only resistors and capacitors from this chip, #5 links to other motherboard side, nearby CYPD5125 (USB Type-C Port Controller)

[mon2]

Test if pin # 5 of this mystery chip reaches the power delivery controller (CYPD5125). You can test by placing the meter in DIODE mode, with no power to this logic board -> one meter probe on the via that is connecting to pin #5; other meter probe to each and every part in this region of the board. Test including each pin on the CYPD5125.

[dhs6512]

Pin #5 has no connection to any component nearby including CYPD5125, except two direct connected to via resistors. And pin #5 has 2ohms to GND, without mystery chip.

[dhs6512]

mon2: thank you for your help. Not found what it is, issued without repair.