LA-G07JP led power shortly and goes off

[ziko07]

Hi, sch is from LA-G07DP but looks similiar. Problem is that 3/5 v ALW comes when bring power short (1-2 sec)
From image all marked GREEN is same, 1-2 sec has power

SPOK colmes 3v3 for short time
en2= 9v4, its normal and is stady voltage
en1= 3v3/5v short same as SPOK
LDO 3v/5V only present short as SPOK
Pin 11 of IC has stady 9.4v but LDO output also goes iff after 1-2 sec
EC_ON on pin112 comes also short time and goes low
Small ic drivers for 3 and 5v alw are SY8286A
Any help please?

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of each and every inductor. Checking for a lower than normal resistance which indicates a shorted part on the board.

Power adapter is suitable to run this board?

[ziko07]

Not seen suspicious resistance, I use to see current consumption bemch lab power but same probl with ori power adapter
when 35v present than board without battery tajes 450mA and there us oresent cou voltage 1.1v 2 ohases,1.0v, 1 2 to ran, fan spinning but after 3 sec all stops, i noticed if I bend pcb (i connected wire to 5v alw coil) than voltsge comes, like some bad soldering or maybe vias on pcb

[mon2]

when 35v present than board

?? 35v is too high for the logic board. This will nuke at least the dcin MOSFETS.

[ziko07]

I'm sure you get point that I meant 3v/5v
Too much syntax errors on my gsm tastature, sorry

[mon2]

Actually no, that is why I asked.

Remove all power. Meter in resistance mode. Measure the resistance between ACP / ACN pins 1&2 directly on the charger IC. Need to confirm the current sense loop resistance is matching the schematic values.

Touch your meter probes together, this same measurement should be matching the ACP/ACP resistance.

[ziko07]

Resistance ACP/ACN is 0.004R, on probe direct 0.001R and drops to 0.000R
Here is image with coil resistance with GND
BQ chip write on it BQ25A...

[mon2]

Full datasheet for the charger IC is posted here:

https://www.ti.com/lit/ds/symlink/bq...=1736098219535

Can you confirm if ACDRV is with ~25v at all times or also shutting off after 1-2 seconds?

Voltage to ground of:

ACOK
ACDET
VCC


Backup your original EC rom and consider to reflash the same - see post # 40 here:

https://www.badcaps.net/forum/troubl...ios-dump/page2

[ziko07]

Will check voltages tommorow, also will put your bios even servicer before me tried ,but strange when I bent, press board on ram connectors missing voltage comes again and after 2 sec goes away again. Like some bad solder or pcb

[SMDFlea]

Will check voltages tommorow, also will put your bios even servicer before me tried ,but strange when I bent, press board on ram connectors missing voltage comes again and after 2 sec goes away again. Like some bad solder or pcb

Loose ram slot pins, check them all

[ziko07]

I couldn't see on microscope, also tried ram in other slot
will double check

[ziko07]

Full datasheet for the charger IC is posted here:

https://www.ti.com/lit/ds/symlink/bq...=1736098219535

Can you confirm if ACDRV is with ~25v at all times or also shutting off after 1-2 seconds?

Voltage to ground of:

ACOK
ACDET
VCC


Backup your original EC rom and consider to reflash the same - see post # 40 here:

https://www.badcaps.net/forum/troubl...ios-dump/page2

Your bin file is 128kB, ori on board is 64kB, its 25X05CL
In attachment my ori dump, the big one bios 16Mb servicer already tried 2-3 dumps

[ziko07]

I give up when bend pcb or press power button all voltages present and goes away after 2 sec
tnx for trying help

[mon2]

Sounds like a PCB break and/or solder joint dry solder that mates with the flexing. Either way, a tough one to hunt down.