I also have a LPM-1 MB 17870-1 Lenovo X1 Extreme with Intel Core i5-8300H and NVIDIA GeForce GTX 1050 Ti 4GB. The device turns on and the fans spin, but there is no image. I have checked all voltages 3V3, 5V, 1V8, 1V2, 1V05, 2V5, and all are present. Only at the PL9001 of the NCP302045MNTWG "VCCGFXCORE_I" is 0V. Can anyone tell me if this voltage should be present at startup? I also noticed that only the CPU gets warm. The GPU remains cold. Does anyone have any experience with this device? Thanks to all.
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This voltage I think is someting about 0,75V or so. It's the Video Graphics Core voltage.
Do you have the correct VIN voltage and a PWM signal at the PWM input? VCC5M present? -
Thank you for your input FriedFred
I have measured all three NCP302045 PUA301, PUA303, PUA201.
VCC5M PIN2 - 5V present
VIN - 20V present
PWM PIN1 - 0.19V
Then I measured all five NCP302045 PU9101, PU8901, PU8902, PU8801, PU8802 of the CPU
VCC5M PIN2 - 5V present
VIN - 20V present
PWM PIN1 - 0.25V
The problems with the defective device started with the fact that it sometimes froze.
I got a second working device. The only difference between the two boards is the CPU and GPU installed.
The only difference I noticed was the voltages at the CPU inductors.
The defective board has an i5-8300H CPU and NVIDIA GeForce GTX 1050 Ti GPU.
PL9101 1V02
PL8902 1V
PL8901 1V
PL8802 1V
PL8801 1V
The working device has i7-8850H CPU and P2000 GPU.
PL9101 0V95
PL8902 0V2 -0V4
PL8901 0V2 -0V4
PL8802 0V2 -0V4
PL8801 0V2 -0V4
Both devices have similar current consumption of around 1.5A. Does anyone know how I can diagnose a defective CPU? Is it possible to measure anything at all?
Unfortunately, the CPU is still glued with a black adhesive, so I don't know if I can even replace it. Does anyone have any experience with the CPU glue on Lenovo devices? If you warm up the CPU, does the glue soften?
Thanks for any good tips to the tech community
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In the schematics I see the "PU9001". Let's stay with this IC.
At the pins "VIN" you shall have the 19V, I think.
At the pins "VCC" and "VCCD" you shall have 5V.
At the pin "BOOT", probably a stable "HIGH".
At the pin "PHASE" a PWM signal. With a simple multimeter, you can measure a low voltage. But not Zero. Zero would mean there is no PWM signal.
At the pin "PWM" there shall be a PWM signal.
At the pin "DISB#" it's the Enable signal. Here the power switch can be switched on and off.
The signals "GL#27" etc. I don't know. Probably not used or so.
At the pins "VSW#16" to "VSW#26" you shall measure the graphics core voltage of about 0.65V to 1.2V. Depends on the GPU.
If you have a PWM input signal and a "HIGH" at the "DISB#" signal and still no voltage at the output, then the Power Switch is defect.
If you do not have a voltage at the output, do you have a short to GND?
You can test this power switch, if you can open the track after the PL9001 and disconnect the GPU. Then it's possible to measure for short circuit to GND and with the use of a low-ohmic power-resistor, like 10R, test the PU9001 for full function.
Another hint can be the voltage across the inductor. The power switch measures the current across the Rdc of the coil. If you can measure a voltage across the coil, then there might flow a current. If you know the Rdc of the coil, you can calculate for the flowing current.
To check a CPU or GPU, you can use alcohol or a thermal image camera.
But even with a very low voltage, let's say 0.5V, you can find a dead-short. A dead-short is always there, right? The CPU and GPU might get conductive up from 0.6V. Then you can look for a hot-spot on the surface of the chip.Comment
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Thank you for your support FriedFred
Of all things, the NCP302045M was glued to the PU9001 position. I removed the NCP302045M from PU9001 and took the one from PU8801 (is the same driver) and installed it in place of PU9001. The NCP302045M on PU9001 was definitely defective, because when I installed it in place of PU8801, the device did not start with it. During the tests, I removed the PU9001 and PU8801 inductors so as not to damage the CPU.
I carried out measurements on the PU9001 WITHOUT the PL9001 inductor installed. Here are the measured values on the PU9001:
(with NCP302045M Driver)
PIN1 PWM = 2V
PIN3 VCC = 5V
PIN5 BOOT = 5V
PIN7 PHASE = 0V
PIN29 VCCD = 5.1V
PIN30 DISB# = 4.8V
VSW = 0V
VIN = 20V
(without P NCP302045M driver, measured directly at the pads))
PIN1 PWM = 2V
PIN3 VCC = 5V
PIN5 BOOT = 0V
PIN7 PHASE = 0V
PIN29 VCCD = 5.1V
PIN30 DISB# = 4.8V
VSW = 0V
VIN = 20V
I have carried out comparative measurements on PU8801 WITHOUT PL8801
(With PU8801 chip)
PIN1 PWM = 0.25V
PIN3 VCC = 5V
PIN5 BOOT = 5.8V
PIN7 PHASE = 1V
PIN29 VCCD = 5.1V
PIN30 DISB# = 4.8V
VSW = 1V
VIN = 20V
(without PU8801 chip, measured directly at the pads)
PIN1 PWM = 0.17V
PIN3 VCC = 5V
PIN5 BOOT = 0V
PIN7 PHASE = 0V
PIN29 VCCD = 5.1V
PIN30 DISB# = 4.8V
VSW = 0V (as no driver is installed)
VIN = 20V
After the measurements, I also installed the NCP302045M back in the PU8801 position and it worked. Unfortunately I do not understand why I have no output voltage at PU9001. I have also measured the output on the PU9001 against ground (without inductor installed) and I have 15kohm just like on the PU8801. What could be the problem?
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I think I'm looking for the error in the wrong place. It has nothing to do with the power supply of the integrated or external GPU. I got the same device for comparison and took measurements. I measured the behavior of the voltages on the PLA301,302,303 inductors for the Nvidia GPU and on the PL9001 inductor for the integrated GPU. Here are the results:
While the device is starting, I have approx. 0.7V at all three inductors PLA301,302,303. If the device is started and shows an unchanged image, the voltage at all inductors sings to 0V. If the image changes (you do something), the voltage at the inductors changes between 0V and 1.2V. I measured a voltage between 0 and 0.25V at PWM PIN1 of the NCP302045 driver.
I always have 0V at the PL9001 inductor during startup and also during use. For me it means that the integrated GPU of the CPU is apparently not used. I could not measure the voltage at PWM PIN1 of the NCP302045 driver because it is glued.
Now I don't know what the cause could be.
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Probably a software like "3D Cinebench" can bring the GPU to work. I think you are right, the GPU is used only with heavy graphical load.Comment
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