Asus UX303UB charging problem green led blinking

[marce002]

Hello

thanks for any clue on this charging problem!

After 3 or 4 attempts of propper soldering the BQ24780 charger IC the laptop boots up propperly, almost fine for everything except for the battery charging part. It runs from AC only and also from Battery only. when the battery is connected linux says charging 10% but after an hour cells volts are 3.75v each and power supply only draws 390 mah so no charging at all.....
the mosfets look fine all, charging coil close to battery connector is 11.1v when battery present and 10,9v with no battery present. in the charger IC bq24780s BATPRES is always 0vol..!

Check voltage at battery connector pins
With charge plugin only

0,82V at +
data and clk 3,2v

pins in the charger shows:

[mcplslg123]

Re: Asus UX303UB charging problem green led blinking

REGN Pin must be 6V approx. Check PD8901. If PD8901 is ok, then most likely Charging IC is bad or not properly soldered. Regn is internal LDO voltage of Charging IC.

[ktmmotocross]

Re: Asus UX303UB charging problem green led blinking

REGN Pin must be 6V approx. Check PD8901. If PD8901 is ok, then most likely Charging IC is bad or not properly soldered. Regn is internal LDO voltage of Charging IC.

on that picture he wrote that REGN is 6V

[ktmmotocross]

Re: Asus UX303UB charging problem green led blinking

check all involved mosfets for short or short to gate.

[marce002]

Re: Asus UX303UB charging problem green led blinking

thanks to all .... yes regn is 6v as described. was inspecting the mosfets and they seem fine all of them 2 in the ac adapter area, 2 for charging and the bat/sys switching mosfet too... regarding soldering yes i think it is ok repased the legs one more time but seems to be ok... BATPRES always 0V...

[ktmmotocross]

Re: Asus UX303UB charging problem green led blinking

data and clock supposted to be 3V

[marce002]

Re: Asus UX303UB charging problem green led blinking

yes they are..... also have battery % visible in linux so there is data feed

look here, many pins with just arround 0.835v ... is it normal? since it is not charging it is....

THIS IS JUST ADAPTER NO BATTERY MEASUREMENTS:

[mcplslg123]

Re: Asus UX303UB charging problem green led blinking

on that picture he wrote that REGN is 6V

Yes my mistake.

[mon2]

Re: Asus UX303UB charging problem green led blinking

See attached datasheet, page 4. See the full description for #BATPRES.

#BATPRES has a bar on the top of the label. This means in digital logic speak that the signal is ACTIVE LOW. So if this line is 0v = logic low, the battery IS present.

Can also write with a hashtag in front to say the same.

Remove the battery and check this pin again.

What is the voltage without the battery on #BATPRES?

Will check the schematic soon but see if a local pull up is missing. This line may be an open drain pin which will then demand a pull up resistor to define the soft high level.

[mon2]

Re: Asus UX303UB charging problem green led blinking

Forget that this is ASUS and no schematics are available.

#BATPRES is an INPUT to this battery charger IC. If LOW, the BATTERY is present.

Power down, remove the battery, check the resistance of PR8930. Value ?

Check and post the voltage reading on pin # 1 and pin # 2 of PR8930.

Then review and report the readings from the next pic. Check the presence of the resistor and cap that are close to the EC.

[marce002]

Re: Asus UX303UB charging problem green led blinking

thanks mon2 , again, ... all my test NO BAT attached...since i stated before: THIS IS JUST ADAPTER NO BATTERY MEASUREMENTS and placed the picture with my volts NON battery plugged..

news :I have replaced the BQ IC and same measurements excepto now I HAVE 5V PROCHOT.
still have 2.6 ACDET , 3v in ACOK, "0V in BATPRES, the resistor PR8930 is 0.005ohm" and 0v each side, RES to ground each pin of PR8930 is 2ohm mmmm..... no battery attached....
PR6004 is ok and 0ohm in the EC side, also caps nearby are ok.
remember the mother does work and turns on, is a no battery charging problem.... battery is ok since it worked from bat only..
mother blinks green line, consumes 300 500 mah ok

[marce002]

Re: Asus UX303UB charging problem green led blinking

this is a 0ohm line straight from pin 15 BQ to the EC i can see..... since it has a ground resistance of 2ohm is the EC bad? weird to detect bat when there is no battery... dont know what to think, or is it the brand new installed BQ....mmm no clues, what else can i test mon2....

[mon2]

Re: Asus UX303UB charging problem green led blinking

hi. I think our frame of reference was incorrect earlier in this thread.

#BATPRES is an INPUT to the battery charger. If this pin is LOW = "0" = 0 volts, then the battery charger is being configured with the knowledge that the battery is present in this box.

For this reason, I think it is ok to see this line as LOW from the EC.

Not sure if this pin is expected to be high but you can perform a quick test as follows:

Remove the 0 ohm resistor that is bridging the EC GPIO pin to the #BATPRES on the battery charger. After this resistor is removed, #BATPRES will be floating.

Next, take a 10k (or any similar resistor) and apply to #BATPRES pad; the other side of the same pull-up resistor to a +3v3 rail on the logic board.

What you are trying to do is to inform the battery charger that the battery is NOT present on the logic board but the hard logic low must be first removed.

Then the charger should allow for the passthrough mosfets to enable and power the logic board. That is the theory.

Can you try this idea and post your result? Please proceed carefully as to not damage the SMD pads or apply any shorts.

Some dialog here on this topic:

https://e2e.ti.com/support/power-man...atpres-funtion

[marce002]

Re: Asus UX303UB charging problem green led blinking

dear mon2 remember the laptop is working fine even with this battery issue, the mosfets in the passthrough stage are working , the laptop turns on normally and boot windows.... only issue is battery charging so the resistor and 3.3v looks a not so good idea, am i wrong?

in case you wonder, when laptop on i have 0,83V at battery + terminals, as stated in my picture with the list of volts:

[mon2]

Re: Asus UX303UB charging problem green led blinking

Ok. In reviewing this thread and the boardview file - the boardview file is noting that PU8901 is p/n sn2867RUYR.

You have replaced PU8901 with p/n BQ24780s.

Are these the same component ?

Also, on this note, see attached data from the internet on the BQ24780s on voltage values.

The following store lists the original SN2867RUYR part:

https://www.aliexpress.com/item/1005...archweb201603_


Update - found this thread on topic:

https://www.badcaps.net/forum/showthread.php?t=85687

However, TI could have done something simple as change the I2C slave address for this battery charger in which case the host (i2c master) will fail to ping and communicate with this charger IC. Just wondering on how compatible is the replaced part for this component. Best to source the proper replacement and then proceed.


Also, watch this video:

https://www.youtube.com/watch?v=tLPeG2YVM3Y

[marce002]

Re: Asus UX303UB charging problem green led blinking

Hi mon2 , yes the video was udseful to me a long time ago its basic.}The post you mentioned is mine with different asus some time ago was fixed.. the point is that you are right im asuming they are equivalent because i have read that somewhere.... pins seem to match. I do not know if 100% identical because I cant find datasheet for the sn2867RUYR...
The laptop anyway is returning % of use in Linux and Windows, and in the last minutes went from 9% to 8% so there is data intrerchange. Cells are now 3.65v each direct bat measurement. it is a 3s .

thanks for your interes and any other idea is welcome, if not I will put back alltogether and report as non fixed, and will work on AC only or battery only (although i will leave unconnected from battery) is a sad scenario so if any other idea appears will be great appart from ordering that sn2867RUYR that will take months to arrive, thanks!!

[mon2]

Re: Asus UX303UB charging problem green led blinking

On your post about the older Asus repair, did you fix the laptop by replacing the same component? The replacement worked for you in the past?

[marce002]

Re: Asus UX303UB charging problem green led blinking

Good question , at that time it was not necesary to replace the CHARGER IC, because the problem was one of the mosfets in the 19v input side close to the DC IN. Replaced with original one M3058M. Another service was repairing it as no power (GL702VM) with a mosftet that was not working properly (4407 BE5V2N) , that was the reason the charger IC was not "charging" the battery that time.

[mon2]

Re: Asus UX303UB charging problem green led blinking

See attached schematic of another Asus laptop that uses the same charger IC for comparison. See sheet 89 (as named on title block). This is pdf 71/83.

[marce002]

Re: Asus UX303UB charging problem green led blinking

thanks for sharing, i was comparing pins and they are identical I would asume it is a direct replacement.... so I do not know what is going on here.... thanks again mon2