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Old 03-28-2022, 12:34 AM   #1
doncius85
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Default Dead Lenovo V-15 ADA

Hello,
Need help. Im working with dead Lenovo V-15 ADA (motherboard GV451&GV551 NM-D151). The laptop is quite new, mfg date 2020-10. Cant find any schematics for it. One of the chip LV5028 had a burned spot on it. Before ordering it from China, decided to do some measurements with chip removed. And now Im not sure will the new chip solve the problem. There are suspicious readings (chip desoldered):
Pin 5 0.4Ohm
Pins 7+8 5Ohm
Pins 17+18 0.5Ohm
Pins 12+13+14+15 - 4.6Ohm
Found some datasheet of this chip (attached). Are theese readings normal? Or the problem is not only the chip?
Attached Files
File Type: pdf lv5028.pdf (88.7 KB, 15 views)
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Old 03-29-2022, 02:09 AM   #2
doncius85
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Default Re: Dead Lenovo V-15 ADA

Any thoughts?
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Old 03-29-2022, 07:29 AM   #3
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Default Re: Dead Lenovo V-15 ADA

Remove PL500 & PL502 and re-measure the resistance on pins you mentioned. If resistance improves significantly, the ic is likely ok and problem is on the load side.
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Old 03-29-2022, 10:51 PM   #4
doncius85
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Default Re: Dead Lenovo V-15 ADA

Quote:
Originally Posted by mcplslg123 View Post
Remove PL500 & PL502 and re-measure the resistance on pins you mentioned. If resistance improves significantly, the ic is likely ok and problem is on the load side.
Nothing changes with 500 and 502 removed. These lines are feeding the CPU, right? Maybe then such a low resistance is normal?
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Old 03-30-2022, 02:02 AM   #5
doncius85
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Default Re: Dead Lenovo V-15 ADA

Quote:
Originally Posted by doncius85 View Post
Nothing changes with 500 and 502 removed. These lines are feeding the CPU, right? Maybe then such a low resistance is normal?
By saying nothing changes I mean there is low resistance on the load side.
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Old 03-30-2022, 07:04 AM   #6
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Default Re: Dead Lenovo V-15 ADA

Post the measured resistance values from your testing.
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Old 03-30-2022, 07:19 AM   #7
doncius85
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Default Re: Dead Lenovo V-15 ADA

All values are at the first post. Measured with chip removed:
Pin 5 – 0.4Ohm
Pins 7+8 – 5Ohm
Pins 17+18 – 0.5Ohm
Pins 12+13+14+15 - 4.6Ohm
Removing jumpers doesn't change anything all values remain the same to the load side.
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Old 03-30-2022, 06:19 PM   #8
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Default Re: Dead Lenovo V-15 ADA

When I see a simultaneous short on +1V and +3V rails, the PCH section of the CPU is usually the cause. Confirm with 1V voltage injection and thermal camera. Board will be good as a donor only.
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Old 03-30-2022, 10:38 PM   #9
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Default Re: Dead Lenovo V-15 ADA

@reformatt is 100% right in assuming that.
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Old 03-30-2022, 10:41 PM   #10
doncius85
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Default Re: Dead Lenovo V-15 ADA

Injected 1V, it draws 1.8Amps and one corner of the CPU gets slightly warm (only visible with thermal cam, can't feel with the finger). So, it's dead CPU
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