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本帖最后由 vusalcrm 于 2021-10-6 05:39 编辑
First of all hello everyone 
It's been along time i didn't post about the repair
One HP G6-2xseries laptop came to the service. Quanta R33
I don't like these models. AMD GPU fail after a certain time. the case also comes in fast. The machine was tampered with at another service.
Lets go Repair 
I visually inspected the motherboard. no resistance breakage and no oxidation.
I connected the machine to the power supply. Yes there is a short circuit. 0.044 this is not normal. but the motherboard is starting. (normal 0.019-0.022 mah)
but if i wait 4-5 seconds before starting the DC jack white led light turns off
The machine draws a current of 0.630mah. Not normal for this card. because current is very low. there is a possibility that there is no voltage in some coils. CPU circuit does not work on this current.
That's why I love thermal camera
Both SIO and Standby PWM get warm. But the SIO that heats Standby PWM. That's why I'm removing it directly from the SIO motherboard. LDO3 (VREG3) line has low ohm resistance. It isnecessary to measure the LDO line before soldering it to the SIO motherboard It's pretty darn good. Kohm - OK
Then I need to measure the ohm value of the 3.3v and 5.0 coils. values are normal. no more short circuit
I soldered the new SIO. Connectedit to DC jack power supply. yes this is cool. standby mode normal - 0.022mah
I excitedly started the motherboard. but the result has not changed yet - 0.630mah
Coils began to measure. and two coils have no voltage. circuit is not completed.
The ohm values on all coils are normal. no short circuit No GPU voltage and no GFX voltage. CPU Core voltages active. VGA_Core –0V (PL27)
+1.0V_VGA – 0V (PL28)
both supply the required mains voltage for the GPU
I measured the main voltage coming to both integrated circuits through the schematic. There is no problem with mains voltages. but the EN signal is 77.2mv (PU14)
This signalis sent by PCH to PU14 (DGPU_PWR_EN) Then, DGPU_PR_EN is sent as a convert from the PR206 resistor to the other IC PU12
so one signal activates two PWMs.
The PCH maybe corrupt. but i'm not quite sure. This line may be short circuited. I measured the resistance of that line. high value kohm. I then removed the resistor (R271) on that signal line from the chipset. I started the motherboard and the voltage coming out of the chipset is still 70mv.
I thought for a while and started measuring the reset signals on the motherboard. All RST signals were fine. Other than the PLT_RST signal. this signal was so weird – 1.9V this PLT_RST signal is connected with CPU, SIO, Ethernet, Card Reader.
I don't believe the SIO is corrupt. I already changed the CPU and tried it. SIO 13pin PLT_RST . I detached this leg from the motherboard. still thesame. There are no results – PLT_RST 1.9v
I removed the Ethernet IC from the motherboard. Usually this IC causes trouble.
I started the motherboard and yes the result is good. PLT_RST - 3.3v and motherboard has image. the current has risen I changed ethernet IC. same situation again. plt_rst 1.9v   this time i started to examine the ethernet circuit
both signals are abnormal. +3V_LAN – 3.3vnormal +1.05V_LAN –1v normal I need to look at where +3V_LAN is coming from. it's a convert signal +3VLANVCC-> +3V_LAN
this signal comes from Dis-charger IC. PU13 there is one mosfet PQ21. 6 pins. Dis-charge activates this MOSFET and 3.3LANVCC isactivated
Now it isnecessary to measure the dis-charge IC. Let's see how is the Gate voltage sent to the MOSFET. When I examined the PU13 IC closely, I saw that the PR168 resistor was broken. Changed PR168 but still the problem persists. This resistance does not play a big role here. Because the voltage through the resistor was normal.
9pin of PU13 sends Gate voltage to MOSFET. But the voltage here is abnormal 55mv
I made an experiment. I applied 3.3v manually to the 9pin. MOSFET tripped. PLT_RST-3.3V activated. and the machine worked normally
Now it'stime to replace PU13 Replaced PU13 and problem solved successfully happy ending 
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发表于 2021-10-6 05:30:40
会员1114439
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