Acer Predator Helios 300 FH52M LA - J891P Rev 1b

[tblazers]

Hi Guys noob here on electronics repairs but have been reading a lot of posts on here for similar boards and issues and have progressing quite a bit.

A bit of history on the board, this is a water damaged Mb, initially I cleaned the board and found that there was a Short on +19 Vb rail (0.6ohm).
I injected voltage (1V) and used thermal cam on the 19 Vb rail and found a cap (PCV97) shorted cap near PUV4. I removed it and short was gone. Attempted power no response, checked 19V rail and shorted again. Injected 1V again and found a cap near PCW52 shorted, removed. And short is gone.

Plugged battery and charger in, battery charging PU301 warm, charger light on
Power button pin 3.3 V
Tried to power on, fan spin, light on, turns off within a couple of seconds.

I noticed I would only have +3VALW and +1.05VALW momentarily after Power button was pressed ( which seems correct looking at power sequence schematic). PU1101, PUW1 and PCH warm up for a few seconds

I read on another post about thermal protection circuitry near DB1 so i have jumped DB1 and removed PB14 and PB13.
Pressing the power button give the same results quick fan spin, but now i have constant power at +3VALW and +1.05VALW. PCH is staying warm, chip looks to have uniform heat, holding at 23 C, is this a bad PCH? All chips mentioned before pulse heat once when power button is pressed.



Now the I have

Checked all rails 19V (xxK ohms), 3V (xxK ohms) , 1.8V (xxKohms), 1.05V (33ohm) no shorts.
Voltage on
PQB11 19.5V - source and gate
PQB12 19.5V on gate and 25V on drain
No shorts on PQZ1- PQZ4
PLZ2 - PLZ4 - approx 3.5 ohm
PLZ1 - 15 ohm
+3VLP , +5VALW, +3VALW, 1.05VALW and 1.8VS all reading correct voltage
One thing i found is 0V on DRAM_RESET ?


Is the PCH toast or should i keep trying?


TLDR
Fixed all shorts on all rails. Have jumped Db1 and removed RB13/14, only momentary power, PCH stays warm when AC plugged in.

Schematic and boardview ---> https://www.badcaps.net/forum/showthread.php?t=120015

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Schematics

[Vesko356]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Schematics

Do not attach laptop schematics and/or BV in this section please!

Schematic Requests ONLY!
https://www.badcaps.net/forum/forumdisplay.php?f=41

Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483

.

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Apologies thanks for linking them

[mcplslg123]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Replace PQB11 as its definitely shorted.When +19V rail shorts, 1st dc in mosfet also gets shorted.

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Thanks for the response,

Can PQB11 still be shorted if i am still getting 19.5 at source and gate, also resistances
S-G >2m ohms
S-D 150k ohms
G-D >2m ohms

?

[mon2]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

I think you may be referencing the wrong pins on the mosfets.

Locate the dimple or white dot on the topside of the part. This is pin #1.

The pins are counted in a 'U' pattern and will be in a counterclockwise direction.

So, pins #1-2-3 = source cluster
Pin #4 = gate = 25v to enable; lower will disable
Pins #5-6-7-8 = drain cluster

Can you confirm?

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Sorry got my S G and D confused,

I do indeed have
19.7V on Drain and 25V on gate, 25V gate for PQB12

[mon2]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Ok. Remove all power. Meter in resistance mode. Check the resistance to ground of the CPU power rail.

Always use only the full and same netnames shown in the schematics. This will make it easier for others to review.

If the label DRAM_RESET# is 0v then this is a fault. The # suffix means the signal is active low. When this signal is a low voltage, for example 0v, then the the dram is in the reset state. This signal must return to a logic high value to operate like normal.

Locate RH46 resistor. Confirm the voltage on each side of this resistor.

Next, remove all power. Meter in resistance mode.

Measure the resistance across the 2 pins of this resistor. Is the resistance ~470 ohms?

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Thanks Mon,
Resistance on CPU rail
+19VB_CPU - 200K
+VCC_CORE - 3.5 ohm

RH46 is reading 476ohm

I will have to confirm the voltage again later today.

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

With AC plugged in and no battery
Confirmed Pin 1 and 2 on RH46 are 0V

Also checked PLM1 for +1.2VP and reads 0v, resistance to ground on the line is approx 160Ohm

[Sephir0th]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Sounds like SLP_S5#/SLP_S4# not even de-asserted, so the "PCH-toast" theory might become true.

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

"might become true"
So might not become true...

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Might not mean anything but when trigger power button i do get a quick
0.5V on pin on pin 2 on RH46 and a ~80mv on pin 1

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Sounds like SLP_S5#/SLP_S4# not even de-asserted, so the "PCH-toast" theory might become true.

What would i expect for voltage amount SLP_S5#/SLP_S4# was in a active state?

[mcplslg123]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

If there is no voltage at PLM1,no point looking for DRAMRST#. MB is stuck at S4 or previous level. Do you have 2.5VP available at PU2501? Have you checked the requirement of PUM1 controller responsible for VDDQ/VTT output?

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

With AC only plugged in i have the following on PU2501
Pin 2 - 0V EN_2.5V
Pin 3 - 3.4V VIN
Pin 4 5V VDD
Pin 6 0V 2.5VP
Pin 7 0V FB_2.5V

Not exactly sure what you are asking about on PUM1


I just check a few pins all i have is
Pin 4 20mV VTREF-1.2V
Pin 16 3.5V LX_1.2VP
What else should I have a look at ?

[mcplslg123]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Going by your measurements, your SIO's requirements are not met. So probe SIO for basic requirements like VCC/EC_RST/ADP_I/VCIN0_PH/RSMRST#/AC_IN/EC_ON/LID SW#/SUSP# etc. Some of these will come after switching the mb-so measure at power off and if dont get any reading, try after trigerring. Post the values. There is lot more to investigate but these basic readings will give us an brief idea.

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

Ac plugged in

VCC
EC_RST# 3.3V
ADP_I 0V 0V on trigger
VCIN0_PH 2.9V
RSMRST# 0 3.3V on trigger
AC_IN 3.3V
EC_ON 5V
LID SW# 3.1V
SUSP#0V 0V on trigger
SYSON 0V 0V on trigger
PM_SLP_S4 3.3V
PM_SLP_S3 3.3V

What else would be SIO requirement ? sorry still a noob

[tblazers]

Re: Acer Predator Helios 300 FH52M LA - J891P Rev 1b

I have ~2.8V on Pin one (SPOK_3V5V) side of DB2, DB3, DB4 - and nothing on pin 2 of these diodes