ASUS FX504G not charging

[Phil916]

Hello,

thanks for boardview schematics and sharing your knowledge 👍

I have ASUS FX504G not charging, it stoped after dead battery, bios battery dead also.

same board DABKLGMB8D0 REV

My checks following kind indications on this topic seems to indicate BQ24780S and PQ21 PQ22 need replacement,
can you help me for diagnostics please ?


Power supply rail entrance mosfet 6414A and the 2 others smaller mosfet near R010 shunt resistor have no short to GND
R010 shunt resistor to GND is 180Kohms and climbing

inductors arround CPU are steady about 4ohms to GND

PQ22 has pins G to S shorted (0,4ohm) D to S = 544ohms
PQ21 has pins G to D to S shorted (0,2 to 0.4ohm)

P-CLK on PIN 4 battery connector to GND is 47Kohms
REGN PIN to GND is 211Kohms, is this too high resistance ?
ACDRV to GND is 114kohms, is this too high resistance ? > so charging IC BQ defective ?

thanks
have a nice day

[mon2]

Hello. The resistance values are high and a good thing to confirm that these pins are not shorted to ground.

Suggest to source another known good battery and test again. Amazon?

Do update this thread.

[Phil916]

thanks will check battery and update

what do you think about shorted gates of PQ21 and PQ22 ?

[mon2]

Agreed that these look incorrect for their resistance. Carefully flux and remove pq21 and check its resistance after it is cooled on your work table. Then check if pq22 resistance is high on the board. It is possible that one or both dcin mosfets are defective.

post the mosfet resistance measurements.

[Sephir0th]

I am seriously shocked, since Post #3 pointed out a internal shorted DC-IN Mosfet already.
I suggest to share a "new" overview of the charging controller. Voltages and resistances and a summary of what components were replaced so far, so someone don't have to move through all 50 posts.

[mon2]

Yes, this thread requires a gps to follow.

post #46 has the resolution that the charger IC was defective. Dcin mosfets were reported to be ok in
post #3 by the op.

then a new poster has a similar case but in this older thread.

[Sephir0th]

19V at ACDRV is per default a shorted DC-IN Mosfet in HPB Design. There exists no other explanation. And the Thread starter shared 19V at ACDRV in Post #3

The only other two possible conditions of ACDRV are 25V (working) and 0V (shorted second Mosfet or something else wrong)

[Sephir0th]

But yes, Thread starter is not the current troubleshooter here. I missed that, my bad.

[mon2]

Np. All good It was a thread started 2 years ago when I was just a pup 😏

[piernov]

That's why the rules https://www.badcaps.net/forum/troubl...f-this-section say:

For each new case please open a new topic, do not post under someone else's topic unless you have something to contribute.

Anyway, moved to a new topic.

[Phil916]

Hello,

sorry for unclarity, i should have posted directly a new topic,
thanks piernov and my apologise for your time.

measurement out of circuit PQ21 (for eference: test leads shorted 0,2ohm)
D to S 0,34ohm
D to G 0,65ohm
G to S 0,54ohm
fautive

incircuit PQ22
D to S 3,1Megaohms or OL
D to G OL
G to S OL
after ohm test G to D, D to S switches ON with 0,26ohm
short circuiting G to S, block the mosfet again...
seems ok though very sensitive little thing

i ordered mosfet replacement CSD17578Q5A for PQ21 and PQ22,
seems to me better to replace both.

[MOD EDIT] Link to schematic - https://www.badcaps.net/forum/troubl...atic-boardview

[Phil916]

Hello,

some bad news
fter soldering 2 new PQ21 PQ22 mosfets i checked and no more short circuit but no change.
At connection power supply goes immediatly in protection mode to 0V, i tried also without battery same result.
seems other compoent is defective, BQ24780S ?