What is this chip? Voltage regulator?

[carl0s]

I am experimenting repairing a dead thinkpad x20. The machines power light
flicks momentarily when the dc jack is inserted or removed.
I accidentally shorted a couple of pins on this IC, and now the behaviour is
much different, with lights doing funny things.

Anyhoo, the machine was dead to begin with..

I wonder if somebody could please tell me what this IC does, and how I might
find a replacement to try out?

Here's a picture:
http://www.uk2sucks.net/ic.JPG

thanks,
Carl

 

[Dave D]

I am experimenting repairing a dead thinkpad x20. The machines power light
flicks momentarily when the dc jack is inserted or removed.
I accidentally shorted a couple of pins on this IC, and now the behaviour
is much different, with lights doing funny things.

Anyhoo, the machine was dead to begin with..

I wonder if somebody could please tell me what this IC does, and how I
might find a replacement to try out?

Here's a picture:
http://www.uk2sucks.net/ic.JPG

If you look closely it appears that on one side of the 'IC' the pins are all
commoned on a ground plane. This implies to me it is a switching mosfet.
These devices and this package style is common in laptops. I'm not sure if
they are readily available, but I doubt replacing it alone will repair the
laptop anyway.

Dave

 

[Dave D]

I am experimenting repairing a dead thinkpad x20. The machines power light
flicks momentarily when the dc jack is inserted or removed.

Did you rule out an AC adaptor fault? Measuring its voltage off load is no
use.

I accidentally shorted a couple of pins on this IC, and now the behaviour
is much different, with lights doing funny things.

There may be more extensive damage now. If the screen is good I'd look on
eBay for a working X20 with a cracked screen.

Dave

 

[Just Another Theremin Fan]

I am experimenting repairing a dead thinkpad x20. The machines power
light
flicks momentarily when the dc jack is inserted or removed.
I accidentally shorted a couple of pins on this IC, and now the
behaviour is
much different, with lights doing funny things.

 

[Chuck]

I am experimenting repairing a dead thinkpad x20. The machines power light
flicks momentarily when the dc jack is inserted or removed.
I accidentally shorted a couple of pins on this IC, and now the behaviour is
much different, with lights doing funny things.

Anyhoo, the machine was dead to begin with..

I wonder if somebody could please tell me what this IC does, and how I might
find a replacement to try out?

Here's a picture:
http://www.uk2sucks.net/ic.JPG

thanks,
Carl

It's a mosfet switcher that provides 5 volts for the usb port.
Digikey in the United States sells these. Chuck

 

[Andy Cuffe]

I am experimenting repairing a dead thinkpad x20. The machines power light
flicks momentarily when the dc jack is inserted or removed.
I accidentally shorted a couple of pins on this IC, and now the behaviour is
much different, with lights doing funny things.

Anyhoo, the machine was dead to begin with..

I wonder if somebody could please tell me what this IC does, and how I might
find a replacement to try out?

Here's a picture:
http://www.uk2sucks.net/ic.JPG

thanks,
Carl

There are several X20 motherboards on ebay right now. One is bad, but
might be used as a parts source. If it was my laptop, I'd just buy a
working one from ebay. The chances of repairing a laptop motherboard
are slim to none unless you know exactly what's wrong with it.
Andy Cuffe

[email protected]

 

[Franc Zabkar]

I wonder if somebody could please tell me what this IC does, ...

Here's a picture:
http://www.uk2sucks.net/ic.JPG

Siliconix Si4435 P-Channel 30-V (D-S) MOSFET:
http://www.vishay.com/docs/70149/70149.pdf
http://www.vishay.com/doc?72123

- Franc Zabkar

 

[carl0s]

Siliconix Si4435 P-Channel 30-V (D-S) MOSFET:
http://www.vishay.com/docs/70149/70149.pdf
http://www.vishay.com/doc?72123

Thanks everybody, your help is very much appreciated. Thanks for the eBay
pointer. I have just purchased a replacement board for £43 including
delivery. Out of interest, is this MOSFET for the USB port then or something
else?

 

[Franc Zabkar]

Thanks everybody, your help is very much appreciated. Thanks for the eBay
pointer. I have just purchased a replacement board for £43 including
delivery. Out of interest, is this MOSFET for the USB port then or something
else?

AFAICT, you have two SMPS circuits in the photo. One uses a low power
MOSFET (Si4435), the other uses a higher power MOSFET (SUD50N03-10).
If I'm right, then there should be two PWM controller ICs nearby. You
can determine the output voltage of each circuit by inspecting the
values of the resistors around the PWM controller IC's error amp pins.
A USB port requires +5V, while the mainboard may run on 3.3V. If you
need more assistance in this area, then a larger photo might help.

- Franc Zabkar