Toshiba Satellite P855 charger disabled after a while

[zioricci]

Re: Charger disabled after a while

ACDRV however is not ok since it should be ~25v to keep the 2 x DCin mosfets ON.

Remove the ~4k resistor on ACDRV and confirm if the ACDRV outputs ~25 volts which is based on power_adapter_rail + REGN voltage = 19v + 6v = 25v.

So if REGN 6V and the two mosfets are ok, it would be plausible that BQ24 is faulty, right? If so, it would mean that the value of ACDRV would depend exclusively on the internal logic of BQ and not on other components external to the IC, right?

Anyway, in another motherboard ACDRV is 25V even in the presence of load i.e. with the 4k resistor

[mon2]

Re: Toshiba Satellite R855 charger disabled after a while

Yes, that is the conclusion at this time. It will be worthwhile to flux and carefully replace the charger IC.

Be patient to allow the solder to melt enough to pluck the device. Gentle tweezer nudge to check if the solder is in liquid state or not.

[zioricci]

Re: Toshiba Satellite R855 charger disabled after a while

I removed the 4k resistor and cmos battery, did some measurements, put the 4k back in, reset the cmos, put the cmos battery back in, and as soon as I plugged in the adapter the power light came on and my eyes popped out , in fact now the ACDRV is at 25V and started only with the adapter

After almost 1 hour it has not turned off, now I put the battery and see if tomorrow morning I find the power light off with the battery selected and the power supply out.

[zioricci]

Re: Toshiba Satellite R855 charger disabled after a while

Yes, that is the conclusion at this time. It will be worthwhile to flux and carefully replace the charger IC.

Be patient to allow the solder to melt enough to pluck the device. Gentle tweezer nudge to check if the solder is in liquid state or not.

if I had to do it, what temperature and air flow do you recommend and at what distance ? Always thanks

[Stevedb]

Re: Toshiba Satellite P855 charger disabled after a while

Practice first on scrap board I use mostly 420 degrees and 40% airflow to put it back 20% airflow and then reflow with 40%

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

Practice first on scrap board I use mostly 420 degrees and 40% airflow to put it back 20% airflow and then reflow with 40%

Thanks!

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

As i guessed, after 6 hours i found the power light off, so i removed the battery, i opened the laptop cover and no boot, i press the start button but no boot, i remove the ac adapter plug and i put it back quickly and the power light comes on and, still with no battery, i hit the start button and the laptop starts up.

Until a few weeks ago everything was fine and if i turned off the laptop i always found the Power light on, regardless of the shutdown time. I imagine that if i did all the necessary measures now I would find everything in order. Acnhe la batteria è in carica.

Is it possible that a faulty BQ24 has this kind of behavior ?

At this moment I brutally took out the battery and the laptop did not turn off.

And I assume that if i leave it on, it will never shut down but if I insert the battery, sooner or later the BQ2 will prioritize this and unplug the AC adapter, and as a witness I will have the Power light off.

Thanks for the changed title !






[Mod. Edit-Vesko356] Use if you want to add something instead of posting a new reply!

[mon2]

Re: Toshiba Satellite P855 charger disabled after a while

Ditto the comments above on the reflow. Practice practice practice on a donor board. Watch lots of YouTube videos on topic by Alex, Louis and others on the procedure.

With only the power adapter connected, which led is on? What is the color of the led?

Respectively, if the adapter is removed and using only a pre-charged battery, the laptop will power on everytime? The laptop will not shut off after xx minutes?

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

With only power adapter connected, led on Is the Power light, white color.
Yes, using only battery the laptop Is on everytime without ever turning off.

[mon2]

Re: Toshiba Satellite P855 charger disabled after a while

Remove all power. Meter in resistance mode. Measure the resistance of the battery mosfet pq205 as measured earlier.

Post the measurements.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

Remove all power. Meter in resistance mode. Measure the resistance of the battery mosfet pq205 as measured earlier.

Post the measurements.

All open with threshold 0.51 v

[mon2]

Re: Toshiba Satellite P855 charger disabled after a while

Flux and carefully remove the mosfet at pq206. Test again.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

Flux and carefully remove the mosfet at pq206. Test again.

PQ206 is ok and without it no short on the two mosfets pq203 and pq204. In the meantime i remembered that time ago i wanted to remove them with hot air and then i gave up because after almost a minute the welds had not melted.

I did now a reflow on these two mosfets about 400 °C, 30% air and after almost 40 seconds i saw the shiny welds.

[mon2]

Re: Toshiba Satellite P855 charger disabled after a while

Given that ACOK is high, the charger deems the adapter to be OK. Based on this status and that REGN is 6 volts, the ACDRV must be boosted and kept boosted to power the board.

Sounds like an internal failure of the charger IC.

After the ACDRV is OFF, after the xx minutes of use. Measure the voltage to ground of REGN. Confirm that ACOK remains high.

Time to replace the charger IC.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

I have now reassembled it and will keep it without the battery to see how long it lasts. It may be that the reflow of now on the two mosfets has solved, we will see again this time.

[mon2]

Re: Toshiba Satellite P855 charger disabled after a while

The 2 mosfets and the charger IC are very inexpensive to buy as spares from Aliexpress or even local stores. The mosfets can be replaced by many others but Aliexpress seems to have it all - just find a reliable vendor with high enough ratings.

Then consider to replace at least the 2nd DCin mosfet if the fault persists. After this, replace the charger IC.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

ok, thanks for the support and all the suggestions.
Ciao ciao

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

Here I am again

I collected some input and then, immediately after i walked away, i noticed that the battery was at 92% but it didn't charge.

I removed the AC adapter and left the battery alone to let it discharge a bit but although it had dropped to 11.50 V, Windows always communicated an autonomy of 92% of autonomy, then casually it went to 100% but the reality is that now the battery does not charge while no problem to boot with only the ac adapter.

Yesterday i did a reflow on the 2 mosfets, tomorrow i'll do it on the BQ725 charger, if the problem remains i think i just have to replace the charger.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

Yesterday i did a reflow on the 2 mosfets, tomorrow i'll do it on the BQ725 charger, if the problem remains i think i just have to replace the charger.

Today i did a reflow on BQ24725 but without success and then i re-soldered all the pins of bq24, they were dull.

I also re-welded PR221 and magically the battery started charging again, and the charging LED became amber but, as already happened, after a while the charging LED went off (100% charged, a coincidence ?).

The evidence is therefore:

charge LED off (charge interrupted or reached 100%), to turn it back on i can do 2 things, either i remove and put back the adapter plug, or i shut down the laptop, in both cases the LED turns on again and battery charging starts again .

If, on the other hand, i abruptly remove the battery while the laptop is on and the charging LED is off, the laptop suddenly shuts down.

Note:
For more than half an hour, the charge has stopped at 99%.

[zioricci]

Re: Toshiba Satellite P855 charger disabled after a while

While waiting for the charger IC to arrive, I measured again the voltages on the charger IC and I think this time they have quite normal values ( see photo ),
but i have this problem:

when the battery is 100% charged the LED remains orange and does not turn white.

What could be the cause, again the charger, or on the Super I/O, since in the motherboard schematic there is the BATT_FULL_LED# signal coming to the Super I/O, or could it depend on the battery itself ?

thx