Acer A315-22 no power on

[pippo_one]

Hi all .. I'm asking for help with a problem with an Acer A315-22
connected to its power supply with the tester I detect the voltage up to the DRAIN of the PQ103 ... then nothing more
I ran these tests
with the mosfet still welded I activated the GATE of the PQ103 and PQ105 I detect continuity with the tester from the Drain of 103 to the Drain of 105 ... but after 10/15 sec the continuity is interrupted
I can't figure out what it could be... can someone please help me
Thank you

[Techtiger]

Re: Acer A315-22 no power on

Test your 2 first N-Fets with out power and uplode the reading after PQ105 you have the CLR ( if you uplode the Schematic we can pin point you it ) test the CLR with out power if short to GND , the Gate of the N fets need a higher V to bypass this supply comes from the for example BQ24725XXX ACDRV pin

[pippo_one]

Re: Acer A315-22 no power on

Hi @techtiger .. I'm a beginner and through you I try to learn as many things as possible and sorry for my non-technical language .... what does "CLR " mean?
please use more basic language with me ...thanks.
Another test performed: the input power supply of the "PU101" is 19 volts...but I can't measure with the "ACDRV" output tester (GATE 4)...Although it can be measured with the tester or it takes an oscilloscope?
I performed this test before your instructions arrived
any help is appreciated

[mon2]

Re: Acer A315-22 no power on

See attached.

CLR should really be CSR = current sense resistor. The charger IC @ PU101 measures the voltage going into this very low resistor value and then the voltage leaving this same resistor. By reviewing the voltage drop from input to output, the charger IC can calculate the current draw = 'load' of the main power rail.

If the voltage drop is too high - for example if the trace is broken, then the charger IC will turn OFF the 2*DCin mosfets you see @ PQ103 and PQ105.

Start with removing all power / no battery. Meter in resistance mode. Measure the resistance to ground of any of the following DRAIN pins 5,6,7,8 on PQ105. What is the resistance? If the resistance is too low, this may have damaged the 2nd DCin mosfet (PQ105).

PQ103 and PQ105 are N-channel mosfets. This means that the GATE voltage pin # 4 must be HIGHER than the voltage being passed between source / drain pins to enable. Otherwise, these mosfets will remain OFF, unless they are leaking.

Respectively, pin #4 = ACDRV on the charger IC and this driver pin should be ~25 volts if all is well. Often, the 2nd DCin mosfet gets damaged and must be replaced - see the very thorough article (sticky) above by @Piernov. It is a must read.

If you do not see ~25 volts on ACDRV, then remove the series resistor @ PR107. Use flux and low air pressure to remove with tweezers. Do not lose this part.

Then power up again. Now do you see ~25 volts at the PCB pad where PR107 was soldered? If yes, then at least one of the DCin mosfets is defective.

Post your details of each measurement.

[pippo_one]

Re: Acer A315-22 no power on

Hi @lun2 ...I carried out the measures you suggested in the following ways:
- with the resistance still soldered on the board, the red lead of the tester to the Gnd of the board and the black lead on the Drain of the Pq105 I measure 315ohm if I reverse the leads of the tester (red to Drain Pq105 and black to GND)
I don't measure any resistance
--I unsoldered the resistance and performed the measurements in the same way: the resistance is now 470ohm
and the other no measure
at this point, as suggested, I gave power to the
card but I do not detect the 25 volts at pin4 of the Pu101
Pls ..any other suggestions?

[mon2]

Re: Acer A315-22 no power on

Which resistor was unsoldered? Is it PR107 = ~4k ohms?

Confirm this by removing all power. One meter probe @ gate pin #4 of PQ103 or PQ105. Other meter probe to pin #4 of PU101. Since the resistor (PR107) is removed, you should NOT measure ~4k ohms in this test.

[pippo_one]

Re: Acer A315-22 no power on

Sorry I got it all wrong delete the post above, tomorrow I will repeat the measures with the correct actions you gave me

[pippo_one]

Re: Acer A315-22 no power on

Hi, I unsoldered pr107 placed at the output of pin 4 of the PU101 .... I applied voltage to the 19 v input, I measured the voltage of pin 4 (ACDRV) and no voltage is detected by the tester
any other suggestions?

[pippo_one]

Re: Acer A315-22 no power on

I update the post with the diagram of my mainboard, in summary I checked the Pq103 and Pq105 as described above by measuring about 315 ohms towards ground com
I unsoldered the Pr107 but from pin 4 of the Pu101 I don't see the approximately 25 volts suggested by @mon2
while in Vcc input of Pu101 I detect the 19,..( pin 28)
I'm also checking the "ACDET" line which according to the diagram should find 2.4 volts but I don't measure them, the line is 0 volts.
Can someone please give me some more input? Thank you

MOD Edit: Link to schematic - https://www.badcaps.net/forum/showth...ghlight=NB8607
Reminder,rules and organization of this section - https://www.badcaps.net/forum/showthread.php?t=117483

[mon2]

Re: Acer A315-22 no power on

Review the voltage to ground of each pin on PQ107.

If PQ107 is enabled, then ACDET voltage will be shunted to ground.

Next, remove all power. Never measure resistance with power. Meter in resistance mode. Confirm the resistance across PR108. Then repeat to test across PR118. The resistance of each resistor must be close to the schematic values.

Next, meter in diode mode. Touch your meter probes together. Should tone beep. One meter probe between PR108 and PR118. Other meter probe to the ACDET pin on the charger IC. Should tone beep. We are checking to see if this voltage divider trace is reaching the charger IC pin.

Finally, meter in resistance mode. Measure the resistance of this required trace again. Should be ~0 ohms.

Post each measurement.

PS: the schematics should only be posted in the schematic section.

[Prutsel]

Re: Acer A315-22 no power on

More input is in the datasheet of the BQxxx . Power managment IC.

Post voltages of all the pins after reading the datasheet.

[pippo_one]

Re: Acer A315-22 no power on

the measurements with the components still soldered on the board are:
Pr108= 260k
pr118= 53k
I measured the continuity between pr108 and pin6 of the pu101 and it's ok.
also at pin 1 of the pq107 I have 6.60 volts and at pin 3 of the pq107 I have 0 volts

[mon2]

Re: Acer A315-22 no power on

If there is a battery attached -> remove it.

Flux and remove PQ7 mosfet that you have just measured. This will stop the shunting of the ACDET voltage.

Then power up again using the official and recommended power adapter.

Without PQ7 installed, you should see a valid voltage on ACDET pin. Confirm it.

Note that this is a bit of a hack but do not see a fault in attempting this for at least a test. Once ACDET is valid, the boosted ACDRV voltage should follow.

[pippo_one]

Re: Acer A315-22 no power on

can i re-solder pr107?

[mon2]

Re: Acer A315-22 no power on

Not yet. This is because a defective mosfet in the power path can cause ACDRV voltage to sink.

1) First, need to be sure that ACDET is in the proper voltage range.

2) Next, check if ACDRV voltage to ground (without PR107) is being boosted or not. (Carefully) check at PCB pad that is mated with pin # 4 (ACDRV) on the charger IC.

[pippo_one]

Re: Acer A315-22 no power on

i unsoldered pq107 ...and i measured "ACDET" now i have 2.75volt
but in pin4 (ACDRV) of PU101 I still have 0 volts.
1-is it possible to argue that the PQ107 does not work properly?
2-if I reweld the PR107 can I make other measurements?
3- do you recommend replacing PQ107?

[mon2]

Re: Acer A315-22 no power on

1) leave pq107 off the board at this time.

2) carefully measure the voltage to ground of the following pins on the charger IC:

Pin 28 VCC
Pin 3 cmsrc
Pin 24 REGN
Pin 5 ACOK

Post each measurement.

[pippo_one]

Re: Acer A315-22 no power on

pin 28 ...19.65volt
pin 3 .... 4 m volt (millivolts)
pin24 ....6.05volt
pin5 .. 13mvolt (millivolts)

p.s.: pr107 e pq107 unsoldered...battery disconnected

[mon2]

Re: Acer A315-22 no power on

Remove all power.

Meter in resistance mode.

Measure the resistance between pins 1&2 (ACN & ACP) on the charger IC. We are confirming if the path between the current sense resistor is ok.

Next, one meter probe on pin #1 or #2 of the charger IC. Other meter probe to ground.

Post each measurement.

[pippo_one]

Re: Acer A315-22 no power on

resistance between pin1 and 2 = 0.02 ohm
red wire Pin1 ->black on gnd = open.
black wire Pin1-> red wire gnd = 330ohm

red wire pin2 -> black wire gnd = open
black wire pin2 -> red wire gng =305 ohm