Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

[glaquerre]

Hello,

I have a Lenovo IdeaPad S145 that does not power on. After pressing the power button (on the keyboard), the white light (in the key) blinks six times when both battery and power adapter are plugged in, or blinks three times when only power adapter is plugged in. In both case, the LED in the DC power jack never lights up. I've tried hard & soft reset (this laptop has a pin hole for reset purpose) without any success.

I've found a shorted capacitor (red circle in the included picture) near a mosfet. This mosfet receives 19V but no voltage at the gate and no voltage at the output (see in picture). Could this capacitor be the culprit?

I've also included a schematics of the motherboard.

Thanks!
Gil

[mon2]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

Hi. If you suspect this capacitor to be defective, test with your meter.

Meter in resistance mode. REMOVE all power.

Meter in resistance mode (2k scale or similar is good).

Check the resistance to ground for both pins of this capacitor.

One side should be ~0 ohms = ground pin.

The other side should not be 0 ohms so if your meter reports a low resistance, then this could be a defective (shorted) cap.

Post your meter reading.

[glaquerre]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

Thanks. Both side of this capacitor is showing 0 ohm. I was not aware that I could mesure a capacitor still in circuit.

[mon2]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

There is a fault on this line.

If you suspect this capacitor, desolder it and check the resistance again for both sides of the pcb pads where this component was soldered.

Post the readings.

[glaquerre]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

Thanks. I removed the capacitor. I'm getting a short on the pads of the PCB. On the other side of the board, I have 4 capacitors that are shorted. I also found that many pins (34, 36, 38 and 40) on the PWM Controller (RT3662AC) are shorted. Is it usual to have a faulty PWM Controller?

[mcplslg123]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

PWM regulator does go faulty. Try removing the pwm first and see whether the short go away. Very likely PWM is bad.

[glaquerre]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

Thanks. I've removed the PWM Controller (RT3662AC) but I'm still having the same shorts. I will continue to investigate.

[Antonynl]

Re: Lenovo IdeaPad S145 no power - Capacitor? (schematics included!)

I've also included a schematics of the motherboard.

Thanks!
Gil

I can't open your attached .tvw file, can you post it in a different format? PDF?