E1-772g Not powering on and not charging

[questore]

Hi guys,

I hope you can help me with my problem. My blind friend had a laptop and it does not seems to turn on anymore or charging. I decided to help him. So here are the simptoms:

-. When (AC is plugged in)and I press the power button It turns on for 1 sec then shuts off and stays that way. I can repeat this any time no matter of the time it spend on charger.
-. If I put battery on, then no charger led lights --> No charging (battery checked on another machine and its fine)
-. CMOS battery holder cracked so no CMOS battery is installed onboard
- I took some multimeter reading on the board to get me going here are they:
BQ735 Charger IC has the following voltages:

NO BATTERY ONLY AC POWER
-20 VCC - 18,7V
-19 PHASE - 2,4V
-18 HIDRV - 2,4V
-17 BTST - 5,8V
-16 REGN - 5,95V
-15 LODRV - -
-14 GND1 - -
-13 SRP - 2,4V
-12 SRN - 2,4V
-11 BATDRV - 0v
-10 ILIM - 3,12V
-9 SCL - 3,3V
-8 SDA - 3,3V
-7 IOUT - 0-0,3V moving
-6 ACDET - 2,65V
-5 ACOK - 3,12V
-4 ACDRV - 24,8V
-3 CMSRC - 19V
-2 ACP - 19,5V
-1 ACN - 19,5V

If battery and AC is connected, then the readings are the same except everyy 2,4V becomes 1,9V
MY first guess is that Charger IC needs replacement, but is that explains the 1 second power shutoff?
Could you help me what could be the problem? I'm not a pro more like a enthusiastic beginner

[questore]

Re: E1-772g Not powering on and not charging

I have ordered a new Charger IC.

According to BQ24735 datasheet, the ILIM gives charge to BATDRV when voltage is above 105mV. and thats not happening. To be continued...

[questore]

Re: E1-772g Not powering on and not charging

ILIM -3.12V seems too high. Shouldn't it be around 0,8V ??
ACDRV also seem high as it should be around 19v, is it not?

[meritosari]

Re: E1-772g Not powering on and not charging

Charge pump output to drive both adapter input n-channel MOSFET (ACFET) and reverse blocking n-channel MOSFET
(RBFET). ACDRV voltage is 6V above CMSRC when voltage on ACDET pin is between 2.4V to 3.15V, voltage on VCC
pin is above UVLO and voltage on VCC pin is 275mV above voltage on SRN pin so that ACFET and RBFET can be
turned on to power the system by AC adapter. Place a 4kΩ resistor from ACDRV to the gate of ACFET and RBFET
limits the in-rush current on ACDRV pin. (according datasheet)

So ACDRV=CMSRC+6=~25V

[questore]

Re: E1-772g Not powering on and not charging

Thank you.
I also found in BQ735 that the ILIM -3.12V means the charging limit is disabled because over 1.6V its all the same until max (7v) voltage.
I also found in BQ735 datasheet the following:
Battery Shorted to Ground (BATLOWV) The bq24735 will limit inductor current if the battery voltage on SRN falls below 2.5V. Mine is 2.4V is it not a problem?

[questore]

Re: E1-772g Not powering on and not charging

I've measured MOSFETS: Q8804 seems fine (Pin5-8 gives 19V, gate gives 2,4V from HIDRV, pin 1-3 gives out 2,4V)

Also did remesured BQ735 ic and noticed BATDRV gives 0.03V.
Correct me if I'm wrong but this means it gets 16 bit instruction of "Charge Voltage Register" Set Bit 5 is this normal? What does it mean? What gives out the ChargeVoltage() 16bit command?
If BIOS sendig this, then could it be that my BIOS chip is currupted?

[questore]

Re: E1-772g Not powering on and not charging

Now at least there is something...
When I plug in only the 10,5V battery, the Q8804 MOSFET pin 1-4 all the same 10,5V and pin 5-8 is 0V. When I plug in ac adapter and battery together then pin 1-4 stays 10,5V BUT pin 5-8 18,5v but no charging led light....

Question to you all: how should I proceed?
1. Should I replace the Mosfet?
2. Should I suspect that the currrent is too low to charge the battery? in this case How should I proceed?
3. Can I test that the chargin led circuit is ok?

[questore]

Re: E1-772g Not powering on and not charging

False alarm, after holding power button for 1 minute, the mosfet is fine, all pins 10volt
So I am still stuck

[questore]

Re: E1-772g Not powering on and not charging

Here is where I have arrived:
1. T9201 measure is 3.1v that is probably why it shuts off instantly on turning on. so FORCE_OFF
2. T9208 is only 0.4-2.6v so too low "VRM_PWRGD" is NOT GOOD
3. U8000 VIN is 19,6v

QUESTION: How should i proceed to know why is "VRM_PWRGD" not good??

[questore]

Re: E1-772g Not powering on and not charging

99.9% that I have the guilty GUY in under my digital magnifier.
R9204 seems to be busted so 0V coming to ALL_SYSTEM_PRWGD that is need to not FORCE_OFF system on Power button Press. I order a new 100kOhm resistor and lets see what happens.

[meritosari]

Re: E1-772g Not powering on and not charging

99.9% that I have the guilty GUY in under my digital magnifier.
R9204 seems to be busted so 0V coming to ALL_SYSTEM_PRWGD that is need to not FORCE_OFF system on Power button Press. I order a new 100kOhm resistor and lets see what happens.

Couple time face intermittent problems mostly was related with resistor, but to find that ones should be always spending lot the time and frustrated.

Especially to trouble shooting a motherboard after "power switch on" (secondary power systems), many lot components which can be the cause.

Good Job!

[questore]

Re: E1-772g Not powering on and not charging

soldered out and mesured but R9204 fine (99KOhm)
BUT ...
VRM_PWRGD output is only 0.5-1V when power button pressed.
According to datasheet below
()
the output should be like 1.73 on 19,5V VIN (VIN measured and fine)
but VRM chip "VRM_HOT#" output is 2V
I don't know where does this comes from? is it comes from sensor inputs difference?
I cannot find detailed datasheet for VRM chip isl95812 to know what does VRM_HOT# 2.0V means.

[questore]

Re: E1-772g Not powering on and not charging

Found a Datasheet for a similar ISL95813 chip (http://www.datasheetspdf.com/PDF/ISL95813/730950/1)
Here are my readings:
- VRM_ON: 3.3V
- VRM_PWRGD: 0.5-1.3V
- NTC: 2.2V when off and 3.3V when POWER button pressed
- VR_HOT: 1.8-2.0V
- VIN: 19.6V
- VDDP: 5V
- PWM3: 5V
- VDD: 4.3V
According to Datasheet:
When temperature rises, then the NTC pin voltage drops. TZONE
value changes accordingly. but TZONE says when Voltage>1.2V then Tmax<76 Celsius that is correct, so VR_HOT is not lowered below 0.8v.
I a'm correct then Temperature is normal, and its got voltage.

[piernov]

Re: E1-772g Not powering on and not charging

VRM_PWRGD should be 3.3V is CPU VCore (+VCORE) is OK (ie. around 1.8V for Haswell).
VRM_PWRGD will be low if CPU VCore is not present.

VRM_HOT# will go low (below 1V) in case of overload/over temperature situation which is not the case here.

[questore]

Re: E1-772g Not powering on and not charging

Thanks for the confirmation about VR_HOT.

I will check +VCORE once I replaced the ground resistor =(2.2hm) that I accidentaly blown

[questore]

Re: E1-772g Not powering on and not charging

replaced ground resistor. 19,5V is back but just untill Q8800
unfortunatelly AC_BAT_SyS seems to be grounded so im guessing something else shorted Now I dont have any idea on what is shorted to ground Damn I was So close...

[questore]

Re: E1-772g Not powering on and not charging

Found out that Q8003 shorted so replaced it, orginal symptom is back.
While I was there It seems I found that the real problem is that most of the VRM chip is shorted to ground. The following pins are all shorted to ground:
VRM_LG1
VRM_LX1
VRM_HG2
VRM_LX2
VRM_RTN
Since I can't found detailed datasheet for ISL95812HRTZ I'm guessing this is a problem!
Am I correct to think that my VRM chip should be replaced??

[questore]

Re: E1-772g Not powering on and not charging

got further : Removed L8001 and L8002
Now VRM chip seems fine, Ground is coming from +VCORE side. Im starting to think the worst...
- R0601 shows that ground closer to Pin Nr: 2 so here we go...

Next I remove CE8005 and CE8002 and see if short to ground is there...

...Success CE8005 was shorted...Ordering a new right a way and see what happens...

[questore]

Re: E1-772g Not powering on and not charging

Cleaned the unsoldered area whele waiting for the new capacitor.
Since I'm done for now measured some points and "Piernov" user was right +VCORE is really around 1.8V I'm hoping for the best... Thats for the help so far.

[questore]

Re: E1-772g Not powering on and not charging

Cleaned the unsoldered area whele waiting for the new capacitor.
Since I'm done for now measured some points and "Piernov" user was right +VCORE is really around 1.8V I'm hoping for the best... Thats for the help so far.

Changed everything but..
I have set wrong multimeter setting +VCORE is 0.18V
1.35V seems to be missing Where is it coming from?