Unsure if missing components are inductors on Gigabyte Z490 Aorus Elite AC

[Wanderer2467]

Hello all.

I am trying to repair a Gigabyte Z490 Aorus Elite AC motherboard that was roughly handled. It had some components ripped off the bottom of the board. The last two I am trying to replace are shown as CKA_FB1 and CKA_FB2 on the schematic and I think they are SMD 0402 30nH inductors to control the resonant impedance of the control rails. I have measured approximately 3.3VDC at CKVDD as per image below. On the board the still in place CKA_FB3 is 1mm x 0.5mm SMD component with a dark body.

I am not familiar with the symbols used in the schematic below if anyone could please clarify what the 30/4/4A/S/X means it would be very helpful. I am guessing the 30 is for 30nH and the pads only allow for a 0402 device.



Thanks for your time in reading this and best regards

[piernov]

Ferrite bead, 30 ohms impedance, 0402 package, 4A current rating is my guess.
X is most likely no stuff. S sometimes mean short instead of populate (PCB itself may have the pads shorted already) but I'm not sure that's the case here.

[Wanderer2467]

Thanks for the help.

The pads aren't clean and when you add it to boardview and schematic which both indicated components should be fitted, I think in both cases something was lost. Rechecking the voltages with the board powered I see VCC3 is at 3.3V and 3VDual is also 3.3V, CKVDD & CKVDDA are around 1V (not as I stated before). VCC3 is directly fed from the ATX PSU so it makes sense that that is the primary 3.3V supply. I think a ferrite bead on the incoming 3.3V supply makes a lot more sense than an inductor. Thanks for the idea.

Cheers

[piernov]

3VDUAL is probably a power rail that's fed by both the 3VSB rail and the 3V rail (so that when machine is turned off it receives power from the standby rail and when it's on it receives power from the main rail).
Most likely only one of CKA_FB1 and CKA_FB2 should be populated, hence why the X on CKA_FB1 which would be no stuff.

[Wanderer2467]

Thanks very much for your help, I certainly would not have considered that the X designates a component not to be fitted without your comment. Looking over the schematic and the actual board there are a number of other components marked with the X that are not populated which also agree with your comment above. Some look to provide an option for either GND or power to an input so definitely makes sense only one of the components would be in place.

It took me a little while but I finally managed to get the correct ferrite beads and installed just the one on CKA_FB2. I applied power and the board booted which was very satisfying. It is now running Window 10.

Again thanks for responding to my post.