Dell 5420 motherboard help

[burtDell]

Hey all

I was replacing my screen on my 5420 and dropped the display connector metal cover piece for a second on the board and a capacitor(?) sparked for a sec

I just want to see what I damaged and how to fix it

GDF40 LA-K419P Rev 2

[mon2]

See attached. Is the board no longer working? Measure the voltage to ground on each side of this ferrite bead. You should measure ~18 volts on each side of this component. This part is present to filter noise on the backlight power supply. Component is a low cost ferrite bead which will under $1 USD in small qty (under $0.10 USD in volume). Digikey / Mouser / Arrow electronics will offer replacements but this part is not critical to be present onboard. The accident may have caused the main power supply to become defective.

Of a larger concern is that the laptop was powered while replacing the screen?? If yes, many other faults may surface.

ALWAYS, remove the power (adapter & battery) before reviewing or replacing parts unless told otherwise for voltage measurements. Otherwise, you are working with an 'electrically hot' board which is extremely risky.

[burtDell]

See attached. Is the board no longer working? Measure the voltage to ground on each side of this ferrite bead. You should measure ~18 volts on each side of this component. This part is present to filter noise on the backlight power supply. Component is a low cost ferrite bead which will under $1 USD in small qty (under $0.10 USD in volume). Digikey / Mouser / Arrow electronics will offer replacements but this part is not critical to be present onboard. The accident may have caused the main power supply to become defective.

Of a larger concern is that the laptop was powered while replacing the screen?? If yes, many other faults may surface.

ALWAYS, remove the power (adapter & battery) before reviewing or replacing parts unless told otherwise for voltage measurements. Otherwise, you are working with an 'electrically hot' board which is extremely risky.

Thank you for that info. I should have added to my original post that the laptop still powers on and I am able to use it without any issues (that I can tell).

No the battery was removed during the replacement. I just didnt know if the replacement screen would work as I scavenged it from my parts bin. Thats why I left that display cover off, powered the machine on, got excited that the screen worked and went to put the cover back on and fumbled the piece. Rookie move for sure.

[mon2]

I think you have dodged a bullet. The spark was just that only. This part is like an electronic resistor. The part will be passive and do nothing unless certain frequencies are present and then the part will perform as a 120 ohm resistor to block that noise. If all is working, leave it be. Nothing needs to be replaced.

[burtDell]

I think you have dodged a bullet. The spark was just that only. This part is like an electronic resistor. The part will be passive and do nothing unless certain frequencies are present and then the part will perform as a 120 ohm resistor to block that noise. If all is working, leave it be. Nothing needs to be replaced.

Thanks mon2! I appreciate the insight and information.