Laptop: Lenovo Yoga 3 14 (80JH)
Logic Board: BTUU1 NM-A381 REV:1.0 2014-11-17
Issues:
Background:
Laptop not turning on. On-board voltage from AC adapter was jumping between 3V (do not recall correctly) and 4.xV, and the fan spinning/stopping on its own.
Initial readings:
Due to PL202 low resistance to ground, removed PJ206 jumper to find short after the coil, on +5ALW side.
Replaced U56 (have some TPS22966DPUR in case of need), U101, U8 that were bad. Short still present (for instance testing C216 +5VS line).
Injected 1V on +5VS line then (after checking CPU, PCH and EC not heating up) slowly increased voltage till 2.8V and found PU701 getting quite hot.
Replaced PU701 (NCP81108MNTXG_QFN36_5X5). Short on +5V was gone. Soldered PJ206. Connected AC adapter and U101 smoked and PU701 shorted again:
Replaced U101. Removed PU701 (that was creating a short again) and that it is so far.
PU701 pads (NCP81108MNTXG_QFN36_5X5):
Suspecting of [PQ802](https://pdf1.alldatasheet.com/datash...D/AON6554.html) but maybe I'm wrong:
Any help on how to proceed / what to check?
Logic Board: BTUU1 NM-A381 REV:1.0 2014-11-17
Issues:
- not powering on
- bottom of the laptop getting hot
Background:
Laptop not turning on. On-board voltage from AC adapter was jumping between 3V (do not recall correctly) and 4.xV, and the fan spinning/stopping on its own.
Initial readings:
Code:
PL202=4.12V 10.5 Ω .010V drop Hot Area PL201=1.06V 44.1 kΩ .320V drop Hot Area PL401=0V 55.4 Ω .143V drop PL801=0.04V 71 Ω .050V drop PL301=0V 112 Ω .174V drop PL101=3.70V (out of scale) .345V drop
Replaced U56 (have some TPS22966DPUR in case of need), U101, U8 that were bad. Short still present (for instance testing C216 +5VS line).
Injected 1V on +5VS line then (after checking CPU, PCH and EC not heating up) slowly increased voltage till 2.8V and found PU701 getting quite hot.
Replaced PU701 (NCP81108MNTXG_QFN36_5X5). Short on +5V was gone. Soldered PJ206. Connected AC adapter and U101 smoked and PU701 shorted again:
- Pins 2-3 (18.5Ω) and 4 (3.3Ω) of U101 with low resistance to ground.
- PJ206: 18.5Ω
- pin 15 of PU701: 16.04Ω
Replaced U101. Removed PU701 (that was creating a short again) and that it is so far.
Code:
PL202= >79 kΩ .331V drop PL201= 45.1 kΩ .322V drop PL401= 55.5 Ω .143V drop PL801= 50-78.4 Ω .042V drop PL301= 940 Ω .279V drop PL101= (out of scale) .405V drop
Code:
Pin 1: 170Ω Pin 2: 95Ω Pin 3: 96Ω Pin 4: 106.4Ω Pin 5: 86.3Ω Pin 6: 198.3kΩ - 305kΩ Pin 7: 32.4kΩ Pin 8: 11.33kΩ Pin 9: 45.7kΩ Pin 10: no reading or out of range Pin 11: no reading or out of range ? Pin 12: 77.5Ω Pin 13: no reading or out of range Pin 14: 0.06Ω (GND) Pin 15: from 1.xMΩ down to 77.2kΩ Pin 16: no reading or out of range Pin 17: no reading or out of range Pin 18: no reading or out of range Pin 19: no reading or out of range Pin 20: 25.6kΩ Pin 21: no reading or out of range Pin 22: 1.99kΩ Pin 23: 1.xMΩ - 76.9kΩ ? Pin 24: 77.2kΩ Pin 25: 10.4Ω (CSREF) Pin 26: 130kΩ Pin 27: 349kΩ Pin 28: 372kΩ Pin 29: 30kΩ Pin 30: 1.07kΩ Pin 31: no reading or out of range Pin 32: no reading or out of range Pin 33: no reading or out of range Pin 34: 2Ω Pin 35: 79.3Ω Pin 36: no reading or out of range
Code:
Diode check: Drain-Source: 0.065V Source-Drain: 0.071V Resistance check: source-drain: 57Ω drain-source: 77.5Ω source-gate: no reading gate-drain: no reading drain-gate: no reading
