LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV:D

[davidtgbe]

Hi there,
I have this laptop which is not powering on/charging with the AC adapter plugged in.

At some point, battery ran out and the laptop did not charge anymore and did not turn on either.

First things checked in the MB:
- Visual inspection. All clean.
- 19V on AC adapter -> OK.
- PD11, PF2, PQ20, PQ21 -> OK (fuse, diode, mosfets)
- C211 shows a short between GND and MX7 line to U20 (don’t know IT8587 internals, may be it is normal).
- PC65 shows a short between GND and 3.3V_ALW2
- Consumption 100mA @ 19V

Thermal camera showed
- PU6 very hot (TPS51285BRUKR)
- PR93 very hot (80°C) -> PWR_SRC resistor to PU6 Vin
- U20 (IT8587) warm.

My first option attemp was to desolder capacitor PC65, however 3.3V_ALW2 short persisted.

The second thing I tried was to inject 0.9V into PR66 (3.3V_ALW2 - S5_ON_R):
- Consumption was 430mA
- Only the U20 (IT8587) warms up to 43°C. Rest of the board seems to be at ambient temperature.

My assumption is that current is flowing to the U20 (IT8587) which would be the faulty component.

I need some help here:
-I don’t know if there could be any other alternative component that could be causing the short.
-In that case, whats the best method to discover it?
-And… in case the culprit was the U20, would there be any chance to repair the motherboard?

Thanks!

[mcplslg123]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

Measure resistance on pin 3/13 of PU6. If any of the pins show low resistance, remove PU6 and check again for resistance. If still value remains low, then very likely its EC IT8987 is shorted. You can confirm that by injecting 1V on the shorted pin of PU6.

EC is programmable,so keep that in mind. Dont connect any power source while PU6 IS removed from mb.

[davidtgbe]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

Measure resistance on pin 3/13 of PU6. If any of the pins show low resistance, remove PU6 and check again for resistance. If still value remains low, then very likely its EC IT8987 is shorted. You can confirm that by injecting 1V on the shorted pin of PU6.

EC is programmable,so keep that in mind. Dont connect any power source while PU6 IS removed from mb.

Thanks mcplslg123
Yes.. Pin 3 (3.3V) is shorted. Removed PU6 and short persists

[mcplslg123]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

So PU6 is very likely ok . IF you have dc supply, you can inject 1V on the shorted pin3(which is connected to a cap nearby). Most likely(almost 90% sure), kbc will heat up.

[davidtgbe]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

I removed U20 and the short is gone. Problem is I don't know how to program IT8587. Is it a matter of having a donor chip or is it there a special software tool to program it?

Anyway I think I'm going to buy another motherboard.

[mcplslg123]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

IT8587 is programmable. You need to buy a new chip and solder it properly on mb. You dont need any special tools to program it as this mb has a unique feature described in Pg 7 of schematic. You just put R157/188/163/185/162/198 as per value described in schematic and it'll get programmed from main bios.

[davidtgbe]

Re: LENOVO U330 DA0LZ5MB8D0 Quanta LZ5 REV

IT8587 is programmable. You need to buy a new chip and solder it properly on mb. You dont need any special tools to program it as this mb has a unique feature described in Pg 7 of schematic. You just put R157/188/163/185/162/198 as per value described in schematic and it'll get programmed from main bios.

Understood... Thank you for all your help mcplslg123!