Gigabyte Aorus 2080ti Xtreme, trying to identify this tiny cap, also get it repaired

[kcdc]

Due to a mishap, C185 (see attached) has been removed as well as damage to the boards insulation, tearing one of the copper paths. The people I've talked to to repair it need to know what kind of cap this is, so I am hoping this community can help me out. Really appreciate it!!

[mon2]

Re: Gigabyte Aorus 2080ti Xtreme, trying to identify this tiny cap, also get it repai

Hi. Taking an educated stab at this, the PCB layout denotes the cap is applied onto impedance controlled traces. The pair of traces with close proximity to each other is the clue here.

Respectively, these are most likely traces linked to the PCIe lane contacts on the gold fingers. Being a x16 lane PCIe adapter design, you can confirm this detail by using a multimeter and checking where you can see copper on the PCB traces. Perhaps allow the repair shop to do this if you are not comfortable.

Test as follows:

a) gently scrape off the black solder mask on the copper traces that are linked to this missing cap.

b) once the trace is bare -> use a multimeter in diode mode -> one probe on the trace and the other side on one of the gold edge fingers. If you hear a tone, that is the confirming landing edge pad that mates with your motherboard. Ideally, if you can count the position of the pad from the notch on the edge connector, then you can review and share here so we can confirm which is the signal linked to this cap. It is possible that this cap is linked to a gold pad on the bottom side of the circuit board.

c) suspecting the cap is a typical DC block cap that is mandatory on PCIe designs. Using a meter in capacitance mode, check the value of the caps @ C165 and C172 - most likely are 0.1uf (104nf) X7R 6v3 (or higher voltage rated). From the picture, look to be 0402 size. The same value could be used here.

Also review and post the resistance values of R111 and R112. Perhaps they are 49.9 ohms each ?

d) if you have ripped / torn traces then you / the repair tech will have to take perhaps a thin strand of copper wire and use it to bridge the break in the PCB trace. Hard to tell where the break is from the pic but a close view with a microscope will reveal all.

Above is only an educated guess as a designer of hundreds of PCIe adapters for the PC industry. Our designs are x1 lane but we follow the same thought process on our designs. With the missing cap, the PCIe signal will not reach the graphics IC - perhaps will cause the adapter to still function but with less # of lanes.

[piernov]

Re: Gigabyte Aorus 2080ti Xtreme, trying to identify this tiny cap, also get it repai

The PCIe traces don't seem to go through the capacitor. Also if that was the case, that capacitor wouldn't be alone.
I'd just shift the nearby capacitor (C172) off one pad (configuration of resistor + capacitor is similar), measure capacitance and put the same cap on C185.
Of course jumper wires will be required to connect the pads (hoping the via isn't damaged), and also to fix the damaged PCIe traces. That's the most difficult part of the job and requires some good experience in this kind of microsoldering.