I am experiencing some vertical black lines in my FPV feed with my new iFlight Nazgul 5 6S.  I have only had 2 flights so far, and haven't made any changes to the PIDs, or really anything else.  I have my VTX set to 400mW, and am running the R-XSR receiver.

The black lines appear as soon as I arm the quad, and get worse with throttle.  Being that it is a new quad, I am not sure where to start to diagnose and fix the issue.  I am assuming this isn't normal for a stock Nazgul 5 6s.  Any advice on what to check, and where to start troubleshooting would be greatly appreciated!

Here is a DVR vid from my goggles to show the black lines:

Black lines is usually means the VTX is not getting enough power. Are you running the VTX off the lipos or a regulated voltage. If regulated voltage, try moving the power to lipo source if your VTX can handle the higher voltage.

Looking at the wiring diagram, I believe the VTX is getting power through the Flight Controller, however I am not sure if it is regulated or not.  I am not sure how I would find that out.  Since my Nazgul 5 is a pre-built BNF quad, I would assume that iFlight would have designed the flight stack in a way where the power source for the VTX would be adequate to power the VTX that came with the quad/flight stack.

Honestly, I don't have the experience/knowledge I would need to try to connect the VTX power source to the lipo as suggested.  Is there anything else I could check/try?  The VTX can do 25/200/400/600mW.  I could try setting it to 200 or 25mW, to see if the lines still occur.  If they don't occur at the lower power levels, would that mean it is a VTX power issue?  Could a different VTX, connected to the same power source potentially fix the issue?

I had no idea black / dark lines generally correlated with power issues. That's good to know.

Willy, from the diagram, it looks like the VTX is being powered off lipo ("BAT" = battery). The best way to check if the VTX is getting the minimum 7V indicated is to use a multimeter to check the voltage coming out of those two wires BAT and GND coming from the FC.

I generally associated lines (any color lines) with noise especially if (1) it especially occurs on throttle and (2) you are tapping straight off lipo like the diagram would suggest. If so, the way to deal with that is with a capacitor at the lipo. Can you see what the writing is on the capacitor? Something like "25V 250uF." Also what is the lipo you are using. Notwithstanding voodoo's assertion that this may be a power issue, I wonder if it's a noise issue.

[edit]

Forgot to add ... never assume these manufacturers know what they are doing. Lots of these "ready to fly" motors (not the Nazgul) were getting burned and ESCs catching on fire because the manufacturer said they were 3S compatible when they were clearly were not. I always sugggest to build your own quad and not go with RTFs or BNFs. Corners are always cut with those builds for the sake of profit.

I rewatched your video, these lines look more clear than black. If you don't already have a capacitor on the lipo pad, I recommend a low ESR 1000uF 35V-50V.

https://oscarliang.com/capacitors-mini-quad/

Thanks for your input guys!

It came with a 50v 470uf Cap soldered to the same pads on the ESC that the XT60 plug is soldered to.  I am running a 6s Tattu R-Line 1300mah Lipo.  I will check the voltage coming off the FC for the VTX and make sure its getting enough volts as soon as I can.  Do you guys think that the 470uf CAP may not be large enough, and that 1000uf may help?

The black lines may be lost in translation between the DVR recording and uploading to Youtube, but I am pretty sure they are black, instead of clear.

I do remember in KababFPV's review of the Nazgul 5, he said the Capacitor could should be larger, but he didn't elaborate much on why.  Maybe it is undersized from the factory, I would just think that if this was a common issue with the Nazgul 5, which is pretty popular, I would have heard about it more in all of the reviews, videos and internet about it.

One thing I do notice though is the antenna cable from the VTX to the SMA mount on the frame does run in between the battery power cables.  Could that be introducing noise in the FPV Feed?

 

Yea I run 35v 1000uF on my 6S builds. 50v if you really want to play it safe but space may be a constraint.

Again, you give the manufacturers too much credit. They'll push the boundaries if it makes better economical sense.

I just wanted to give an update that I resolved my issue!  I ended up getting a new VTX (Rush Tank Ultimate), and that completely fixed my issue!  Powering the camera off the VTX, or a bigger Capacitor may have also fixed the issue, but this was the easiest option for me, and the VTX that comes with the Nazgul isn't great anyways.  Besides, a 50V 1000uf cap is huge and I would have space issues.

The best part is that the Rush Tank and the Old VTX wiring harness is the same, so it was basically just a 15 min plug and play process!