ASUS Q407i Component Identification Help

[cypher2001]

Hey all

Trying to diagnose a ASUS issue. I seem to have located some shrapnel and what looks to be a missing part. I believe its a replica of the attached part below.

I can't seem to identify the part. Not sure if its a cap or inductor. My google-fu is pretty weak it seems. Anyone familiar with this manufacturer or part that can lend me a hand?

[mon2]

Re: ASUS Q407i Component Identification Help

Still in training under Sensei Bolo Yeung but inductors do not have polarity.

This is a polarized e7 case tantalum capacitor.

Zoom out in your picture so we can review what is nearby to locate a suitable value for the part.

[cypher2001]

Re: ASUS Q407i Component Identification Help

Seems I might be able to answer my own question... I'm thinking this is a tantalum cap. 25V 15uf.
Not sure of manufacturer...

(Sorry.. Was replying before I saw the post above!)

[cypher2001]

Re: ASUS Q407i Component Identification Help

Still in training under Sensei Bolo Yeung but inductors do not have polarity.

This is a polarized e7 case tantalum capacitor.

Zoom out in your picture so we can review what is nearby to locate a suitable value for the part.

Thank you.

Larger view attached. You can see the part to the left on the picture is missing. There is a single leg still soldered. It looks like the other side was never fully flowed and made inconsistent connection. Eventually it zapped. This is my current working theory

[cypher2001]

Re: ASUS Q407i Component Identification Help

I was able to find a full picture of the mb online

https://ibb.co/fpRWWxx

in the upper right quadrant, you can see the area from my picture and it clearly shows a cap missing.

The PC does boot up -- but will hang/black screen at a random time after booting (usually 2-3 minutes but sometimes as quick as 10 seconds).

Stanger still -- I am able to boot to a USB Ubuntu image with no problem and no hangup. It seems only when using the NVME drive that this occurs. I've already attempted to change out the NVME drive itself. No change in problem.

Just figured there might be interest in the problem for those still reading along.

[mon2]

Re: ASUS Q407i Component Identification Help

USB is a high speed serial interface.

NVME will be PCIe bus interface.

Respectively, check for any missing or damaged parts near the NVME socket. There should be a mix of DC blocking caps for the PCIe interface (data & clock) @ 0.1uf. They must be present and if any are missing or damaged, the PCIe bus will not function.

[cypher2001]

Re: ASUS Q407i Component Identification Help

USB is a high speed serial interface.

NVME will be PCIe bus interface.

Respectively, check for any missing or damaged parts near the NVME socket. There should be a mix of DC blocking caps for the PCIe interface (data & clock) @ 0.1uf. They must be present and if any are missing or damaged, the PCIe bus will not function.

Thanks. I have visually inspected that area and failed to find anything missing or showing signs of damage.
Its not that the the drive does not work at all. On the contrary, I have re-installed multiple operating systems onto both test drives. Sometimes they do not complete but sometimes they do and then fail sometime after booting. it certainly doesn't help troubleshooting when the problem is intermittent.

In the end, the problem occurs enough to ensure a fix. I'm hoping this cap is part of the power distribution. My running theory is that the NVME+CPU draw is too much without this cap and the system halts. Perhaps I'm stretching. If this cap doesn't fix the issue, I'm back to square one.

[mon2]

Re: ASUS Q407i Component Identification Help

Yes, that is quite possible. Try this:

1) remove all power -> meter in resistance mode (lowest scale).

2) use the meter probe with one lead on the missing capacitor -> the other meter lead to ground. Is the resistance ~0 ohms ? If yes, THAT pad is the capacitor's GROUND pad. Make a note of it when you receive the replacement capacitor.

The tantalum caps are POLARIZED so the '+' MUST be on the pad that is NOT ground.

3) Now use the meter probe on the '+' pad of the logic board and use the other meter lead on the NVME connector. Start on one side and continue to measure for each pin on the soldered connector. Do you see any resistance values ~0 ohms ?

If yes, then you know for sure the missing capacitor is used to filter the power rail of the NVME.

Measure the physical size of the missing capacitor area and be sure that your replacement is the same size. From earlier post, the 'E' code should define the size of the part.

The voltage of 25V is ample since the NVME will not be this high of a voltage rail.

PCIe bus uses 3v3 and 12v rails ONLY. We design 99.99% of our products to use only the 3v3 rail but either way, your end products will be 12v or under in operation.

[cypher2001]

Re: ASUS Q407i Component Identification Help

Sadly... The cap was replaced but the PC still exhibits the same issue.
I've checked a few points and see no voltage changes when this black screen appears.

I"m somewhat stumped.