I'm attempting to repair this very old laptop without any schematics as it has been impossible for me to find one. The laptop has no power whatsoever when plugged in. I've tested the charger cable and charger port and the Voltage was good. When i moved on to the module in question one of the three contacts i tested had no V, the upper right contact i haven't tested because my multimeter doesn't fit. Are any of the contacts in this module suppose to have 0 V?

 

It looks like a common-mode choke, with 4-pins. Not shielded but with a plastic case around it?
I would check the 8A fuse and the diode with a big chip taken out of it.

 

It looks like a common-mode choke, with 4-pins. Not shielded but with a plastic case around it?
I would check the 8A fuse and the diode with a big chip taken out of it.

I agree with it being a common mode choke, but likely with a pressed ferrite material around the outside. Commonly used with inductors and other similar wound applications.

https://en.wikipedia.org/wiki/Ferrite_(magnet)

See the soft ferrite section.

 

It looks like a common-mode choke, with 4-pins. Not shielded but with a plastic case around it?
I would check the 8A fuse and the diode with a big chip taken out of it.

I had checked the fuse and it was fine. I do have to ask-what big chip with are you referring to?

 

I agree with it being a common mode choke, but likely with a pressed ferrite material around the outside. Commonly used with inductors and other similar wound applications.

https://en.wikipedia.org/wiki/Ferrite_(magnet)

See the soft ferrite section.

OK, But wouldn't the power brick in the charger cable take care of the noise?

 

Noise has to be killed at the source,
else it radiates.

If it was up to the power brick to kill the noise of the laptop, then the cable between the laptop and the power brick would radiate. You might have seen the lumps around some cables, which are retrofitted when the item fails Em testing, and are there to stop the item radiating up the cable.

hence the choke on the PCB, to stop the noise getting out side.

 

Awesome. Thanks to everyone