Dell Inspiron 15 LA-9982p No power help please

[harshana]

Motherboard: LA-9982p Rev3.0


when I turn on power light appears but no display and even the fan is not spinning. I tested all the voltages.

everything seems fine when standby stage. when I press power button, laptop takes around 0.6A and CPU/PCH heating(cause fan doesn't spin)

when I check main signals I saw that SLP_S3# is missing and 1.4v at SLP_S4.

also SUSP# missing. because of that No power at bios 8th pin.

SUSP# and SLP_S3# resistance seems OK.

Can you guys help me please. I have no idea to continue from here. Is this about faulty CPU? or is there any luck to fix this.

[mon2]

Re: Dell Inspiron 15 No power help please

Hi.

What is the voltage of CHG_B+ ? This is the #1 voltage required to get started.

Voltage of ACOK on PU701 (charger IC) ?

Not familiar with these models but you can review the following:

1) susp# appears to be driven by the EC controller but the group of pins on the EC are marked as GPI which should mean as 'input only' ??

2) is U2302 bios being powered at pin # 8 ? (+3VS)

3) study the block diagram on sheet 46 for the power diagram

a) do you see the DCin voltage reach the logic board when ON ?

b) each regulator onboard is using this higher DCin voltage to power lower power rails (buck convertors) - confirm each voltage at the local coils.

4) with NO power / no battery -> check the resistance to ground of the +CPU_CORE. This is to check if the CPU could be possible damaged already.

[harshana]

Re: Dell Inspiron 15 No power help please

Hi.

What is the voltage of CHG_B+ ? This is the #1 voltage required to get started.

Voltage of ACOK on PU701 (charger IC) ?

Not familiar with these models but you can review the following:

1) susp# appears to be driven by the EC controller but the group of pins on the EC are marked as GPI which should mean as 'input only' ??

2) is U2302 bios being powered at pin # 8 ? (+3VS)

3) study the block diagram on sheet 46 for the power diagram

a) do you see the DCin voltage reach the logic board when ON ?

b) each regulator onboard is using this higher DCin voltage to power lower power rails (buck convertors) - confirm each voltage at the local coils.

4) with NO power / no battery -> check the resistance to ground of the +CPU_CORE. This is to check if the CPU could be possible damaged already.

CHG_B+ ———> 19v
PU701 (ACOK)——> 3.7v

1. according to schematics SUSP# is both input and output I guess.
2. No. U2302 has no power at pin 8.
3.

a) DC in voltage is appearing.
b) I can only see 3v and 5v at coils.

SYSON, VRON# and SUSP# signals are missing even after power btn. because of that I can’t see 1.5v and 1.35v

This motherboard doesn’t have VGA chip.

4. with no power CPU CORE resistance is 144ohms. seems like good.


Any luck ???

[mon2]

Re: Dell Inspiron 15 No power help please

Is the EC being powered? Measure the voltage.

[harshana]

Re: Dell Inspiron 15 No power help please

Is the EC being powered? Measure the voltage.

yes. Pin 9,22,33,96,111,125 and 67 have 3v.

[mon2]

Re: Dell Inspiron 15 No power help please

Review this thread:

https://www.badcaps.net/forum/showthread.php?t=90578

[harshana]

Re: Dell Inspiron 15 No power help please

Review this thread:

https://www.badcaps.net/forum/showthread.php?t=90578

In my case RSMRST# is present after pressing the power button.

SIO_SLP_S4# also present. but SLP_S3# missing

[mon2]

Re: Dell Inspiron 15 No power help please

Wait on others to comment but from:

https://www.leakymosfet.com/blogs/ne...op-motherboard

If SLP_S4# and SLP_S3# does not come out when the power button is pressed, you may need to reflow, reball or replace the PCH.

[harshana]

Re: Dell Inspiron 15 No power help please

according to the link you sent, SLP_S5# should present before slp_s3.

But SLP_S5 is missing.

RTCVCC has 3.3v

I am unable to test other signals related to rtc because there is no sodler pad to test.

How can I test RTC Section? Or dont I need to test that section. What should I do next???

[harshana]

Re: Dell Inspiron 15 No power help please

any luck

[mon2]

Re: Dell Inspiron 15 No power help please

Remove all power. Meter in resistance mode.

Check SIO SUSP# pin resistance to GND.

[mcplslg123]

Re: Dell Inspiron 15 LA-9982p No power help please

Are u sure laptop takes 0.6A when turned on while SUSP# is missing?? Seems like impossible to me. Had you checked Q8 is working or not. Measure voltage on U2301, PIn 1-2/13-14/6-7/8-9/3/4.. Voltage on J513(3VALW_PCH) is present??

I just repaired LA-9981(with graphics). Was dead. 3/5V PWM ic was corroded. Replaced this regulator. When turned on light glows but consumption moves from 0.010 mA to 0.019mA only. In my case also SUSP# was missing. Replacing U2301 fixed it. Hope this helps you but no case is same-so keep that in mind.

PS: No need to rest RTC section for now as it turns on and power light is glowing.

[harshana]

Re: Dell Inspiron 15 No power help please

Remove all power. Meter in resistance mode.

Check SIO SUSP# pin resistance to GND.

SUSP# to ground——-> 76kohms (200k range)

[harshana]

Re: Dell Inspiron 15 LA-9982p No power help please

Are u sure laptop takes 0.6A when turned on while SUSP# is missing?? Seems like impossible to me. Had you checked Q8 is working or not. Measure voltage on U2301, PIn 1-2/13-14/6-7/8-9/3/4.. Voltage on J513(3VALW_PCH) is present??

I just repaired LA-9981(with graphics). Was dead. 3/5V PWM ic was corroded. Replaced this regulator. When turned on light glows but consumption moves from 0.010 mA to 0.019mA only. In my case also SUSP# was missing. Replacing U2301 fixed it. Hope this helps you but no case is same-so keep that in mind.

PS: No need to rest RTC section for now as it turns on and power light is glowing.

Im facing a power cut now. I will share photographs showing the DC unit. It take 0.605A when I power on. also will check voltages at U2301. (as I remember when I test U2301, I saw input voltages are there but enable signals were missing)

Unfortunately Still I wasn't able to find Q8 on my board. if you own boardview for this laptop, can you share with me please

[harshana]

Re: Dell Inspiron 15 LA-9982p No power help please

Are u sure laptop takes 0.6A when turned on while SUSP# is missing?? Seems like impossible to me. Had you checked Q8 is working or not. Measure voltage on U2301, PIn 1-2/13-14/6-7/8-9/3/4.. Voltage on J513(3VALW_PCH) is present??

I just repaired LA-9981(with graphics). Was dead. 3/5V PWM ic was corroded. Replaced this regulator. When turned on light glows but consumption moves from 0.010 mA to 0.019mA only. In my case also SUSP# was missing. Replacing U2301 fixed it. Hope this helps you but no case is same-so keep that in mind.

PS: No need to rest RTC section for now as it turns on and power light is glowing.

Voltages at U2301 after power on.

1,2—-> 5v
13,14—->0v
6,7——>3.3v
8,9——->at the beginning 0.27v and after some time it turn into 0.96v
3—>0v
4—->5v
5—-> 0v


Voltage at J513 ——-> 3.24v

here I attached DC unit photo also when I power on. still Im unable to find Q8

[mcplslg123]

Re: Dell Inspiron 15 LA-9982p No power help please

Q8 is located near Audio jack(between audio jack and 51225C IC). Its a 2N7002 mosfet. Just replace it with any mosfet marked 702/K72/S72 which you can get plenty from scrap boards.

Yes, indeed your consumption indicates a short somewhere.Under normal circumstances, when SUSP# is missing on this mb, consumption wont exceed 100mA (after turning on) as SUSP# is the enable for almost each and every IC.

Measure resistance on each and every coil in ohms mode without power.

[harshana]

Re: Dell Inspiron 15 LA-9982p No power help please

Q8 is located near Audio jack(between audio jack and 51225C IC). Its a 2N7002 mosfet. Just replace it with any mosfet marked 702/K72/S72 which you can get plenty from scrap boards.

Yes, indeed your consumption indicates a short somewhere.Under normal circumstances, when SUSP# is missing on this mb, consumption wont exceed 100mA (after turning on) as SUSP# is the enable for almost each and every IC.

Measure resistance on each and every coil in ohms mode without power.

I replaced Q8 with S72 mosfet. Still nothing changed.

when I test resistance at coils the lowest resistance I was 70ohms at PL301 and another lowest was 90ohms at PL502.

I guess Thats normal. May be I was wrong.

Important thing is CPU is heating. Thats the guy who takes that 0.6A after power sw on. CPU died??? or can we continue ??

[mcplslg123]

Re: Dell Inspiron 15 LA-9982p No power help please

When SUSP# is missing, Vcore cant rise.So cpu should'nt heat at all. Please confirm whether CPU is heating or PCH part of SOC is heating?? However, both the parts of SOC shouldnt heat in absence of SUSP#.My doubt goes towards a shorted SOC or any rail which goes to SOC.

[harshana]

Re: Dell Inspiron 15 LA-9982p No power help please

When SUSP# is missing, Vcore cant rise.So cpu should'nt heat at all. Please confirm whether CPU is heating or PCH part of SOC is heating?? However, both the parts of SOC shouldnt heat in absence of SUSP#.My doubt goes towards a shorted SOC or any rail which goes to SOC.

I see square and rectangle there. square part is heating up. My mistake. PCH is the part heating up. I thought its cpu.

anyway Means PCH dead or continue?

[harshana]

Re: Dell Inspiron 15 LA-9982p No power help please

Any Luck