Acer Aspire F5 573G power issue

[bembeno]

Acer Aspire F5 573G da0zasmb8d0 rev d no power when i measure the volt on the curent resistor i found 3.4 volt on the two sideswhile connecting charger also the charger volt is 19.5 volt

[mon2]

Re: Acer Aspire F5 573G power issue

1) link a schematic if available

Perhaps the same as yours?

https://www.badcaps.net/forum/showth...ht=da0zasmb8d0

2) what is the charger IC onboard ?

3) review the input DCin mosfets from the DC adapter to the current sense resistor you are measuring. Check the resistance (with NO power) of:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

4) Remove all power -> measure the resistance to ground of the current sense resistor you are measuring -> if the resistance is low, there could be a shorted component on this main power rail causing this 19v to be so low.

Or the fault could be that the DCin mosfet is defective and not allowing for the power path for the 19v onto the main voltage rail.

Update:

See attached -> review each of the referenced parts and arrowheads. Start with the diode @ PD3 - what is the voltage BEFORE this diode and AFTER this diode - connect your external adapter (remove your battery).

Need to play a plumber to fix a leaky faucet with a stripped allen screw..bbl.

[bembeno]

Re: Acer Aspire F5 573G power issue

the resistance
source & dran = 67 k
gate & source= 600 k
gate & drain = 400 k

[bembeno]

Re: Acer Aspire F5 573G power issue

the resistance between the curent resistor and the ground = 4 m

[bembeno]

Re: Acer Aspire F5 573G power issue

i fixed the problem by make jumber between thr drain and the source of the DC mosfet

[mon2]

Re: Acer Aspire F5 573G power issue

The mosfet you have bridged should be replaced. It serves a purpose otherwise the bean counting accountants would have left the part off the design.

[bembeno]

Re: Acer Aspire F5 573G power issue

i know but its not the mosfet i think its the charger ic because when i bridged it i found on the gate 25 volt this volt should come from charger ic BQ24780 to connect drain with source but without this bridge no volt on the mosfet gate

[mon2]

Re: Acer Aspire F5 573G power issue

Check if the Vcc is ok on the charger IC without this bypass. Also check REGN pin. Both are common test points for this 'BQ' series of charger ICs to build the boosted ACDRV voltage.

The Vcc rail is fed from the raw DCin adapter and often through a dual common cathode diode (one from the DCin; other from the battery feed).

If you have such a dual diode (sot-23 package) - check if perhaps this diode is defective.