Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when apply

[ktmmotocross]

Acer 515-54G
DA0ZAWMB8G0

Board have badly burned Main power and second mosfet After repair ACDET is pulled to GND when apply power

i dont uderstand this. Charger ic BQ24780S

ACDET 6pin have voltage devider set to R1 110Kohm and R2 20Kohm. pin ACDET have 20K to GND. But when apply power R1 have 19V on one side and 2.3ohm on other side.
What is pulling my ACDET down when i apply power even without BQ ic

[Sephir0th]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

Is this what stares at me in the second picture what you call the "repair"?

Well, to stay polite, i don't want to go into the details but it doesn't looks like that you tried to get rid of the carbonised layers. Any scraping, dremel or drill action done before throwing the solder wick onto the board?

[ktmmotocross]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

Is this what stares at me in the second picture what you call the "repair"?

Well, to stay polite, i don't want to go into the details but it doesn't looks like that you tried to get rid of the carbonised layers. Any scraping, dremel or drill action done before throwing the solder wick onto the board?

u need better glasses. that repair is allready drilled and masked. but flux not cleaned yet

when i jump first two mosfets laptop work. so only issue is that power started short on ACDET

[ktmmotocross]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

sadly i must close this case because owner is ucraina trucker and must go.
so i end up just drilling masking and jumping voltages.

If anyone have hint why that ACDET short i will be glad to hear it, because it is interesting fault

[mon2]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

If I am reading the first post correctly, the resistance is being measured after the power adapter is plugged in and turned on?

Resistance and diode mode checks are never to be made with power to the logic board.

[mcplslg123]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

Fully agree with @mon2's observations and perhaps that answers the question.

[ktmmotocross]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

guys i need advice not specuation. resistance measurement was just adding value to allready known fact that ACDET is puled down when apply power.

[mon2]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

The voltage divider resistors may be defective if you see a stable 19v on the high side resistor. In hindsight, I think you meant to write 2v3 on ACDET pin? Are these resistor values the same as in the schematics?

[mon2]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

See attached.

reference:
https://ohmslawcalculator.com/voltag...der-calculator

If the resistors are indeed as noted, the output voltage should be 2v9.

The TI reference design notes other possible resistor values that can be used for ACDET.

[mon2]

Re: Acer 515-54G badly burned Main power -After repair ACDET is pulled to GND when ap

More..review if you have PQ17 onboard. If yes, remove it and check the voltage to ground again on ACDET.

The resistor values in the schematic are different but quite possible that the PCBA shop just replaced the original to the values on your board - this is fine as long as the ratio of the high and low side remains the same, for the same ACDET voltage.