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I need help with troubleshooting my FPV Drone

#1
Hello!
I recently build my first Quad but i have some Problems with my Video/ VTX.
After a drone crash i had to resolder my VTX back to my FC, i think it lost the connection due to some vibrations, since then my VTX sends no more RSSI signals to my FPV Goggles, my VTX powers up/ lights up and sends sometimes after clicking 100 buttons randomly and moving the antenna a video signal which is perfect, but after a small time i lose it again, now i thought my vtx is broken so i bought a new one, but this time the VTX doesn't even power up (no lights/ nothing). Now i am confused and i have no idea where the problem could be, did i got an broken VTX?
Is my new VTX too good for the FC? I have no ideas.
FC: https://www.banggood.com/9_4g-30_5x...-OSD-5V-BEC-and-Current-Sensor-p-1226610.html

First Vtx which still works a little bit:
https://www.banggood.com/Mini-VTX58...Transmitter-Module-OSD-Control-p-1257034.html

New Vtx which looks dead:
https://www.banggood.com/Eachine-TX...mitter-Support-OSD-Configuring-p-1248768.html

I am really searching for help and i have no idea what to do next or where the problem could be (My drone is a mix from the UAV-Futures 99$ Build Base and Pro version)
 
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#3
I know these soldering connections are a shame xD, but at least it worked. I don't know if you can see something? At the moment everything is a little bit provisionally i switched too my old vtx too to check if it still has the same problems and gets power and yes it has the same problems as before -.-
Maybe you can see these small dots in the pit near number 26 and near the font FC-F4 i am not sure, but I think, when I ordered the fc, they were not there yet, probably they accidentally somehow got there, but i was able to fly with these mistakes so why should this now be the problem?
 

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IanSR

Active member
#4
Erm I hesitate to ask but you say it send no more rssi data to your googles, are you sure the rssi wire hasn't come off, or the setup in betaflight has been changed to the wrong channel?

Or do you mean video? If you mean video, remove the flight controller from the equation and see if that works, i.e.

power the vtx from a Bec/lipo/psu etc. NOT THE FC but something else you can get a stable power from.
If you get a black screen on your headset (or video if you decide to attach a camera, but it's not needed for this) the vtx is fine (presuming everything is setup right and on the same channel), if you get only snow (static) then the vtx is likely dead.

if that all works, connect the vtx to the FC, if you then get static, then the FC is not supplying enough power.

Of course, this does assume both the vtx and your headset are both on the same frequency, check that first lol
 
#5
Thank you for your answers, so that you can imagine this better, I wanted to specify something more.

On the first 2 pictures you can see what happens when the vtx is lying on the floor. All led lights lights up and down at the same time. It also seems to happen to the RSSI signal, because that jumps back and forth just as if the power supply was somehow not constant.
Sadly i am not able to send you a video, but i made some screenshots for you.

If I move the Vtx, especially if I move it away from the drone, then it finds its channel, the right led's lights up and an RSSI signal is available and the video is perfect.



power the vtx from a Bec/lipo/psu etc. NOT THE FC but something else you can get a stable power from.
If you get a black screen on your headset (or video if you decide to attach a camera, but it's not needed for this) the vtx is fine (presuming everything is setup right and on the same channel), if you get only snow (static) then the vtx is likely dead.

if that all works, connect the vtx to the FC, if you then get static, then the FC is not supplying enough power.
Technically, my vtx or my FC could be the problem if i understood that correctly, but I bought a new second vtx, which does not light up, as if he also did not get enough power, it would be very unlikely that I got a broken vtx and since my solder joints anyway look pretty bad, it would not hurt to install a new Flight Controller, is that right?

But why do the 2 vtx react so different?

Nevertheless, many thanks for your answer, i think i will just buy a new FC and try it out
 

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IanSR

Active member
#6
Ok I think we e got crossed wires here, when you say rssi you are talking about the signal strength shown in the photos of your googles yes?

I'm not 100% sure where the fault lies but you need to try and power the vtx from an external source (maybe even just a 1s will do) as like you I suspect the FC to be at fault, but the original vtx and new one is sending conflicting info, so eliminate the FC for a moment and try to power the VTX's directly as a test, this is the only way you'll be able to test them properly.
 

IanSR

Active member
#7
I've just retread your reply, I think from the description you give the power wire has probably got a wonky joint on the flight controller, when you move the vtx away and it works, you're probably pulling on the solder joint in such a way as to improve the power connection so the vtx gets past its initial initialisation and works normally, the other vtx could either be dead or just has a different tolerance for the power it needs.

You got a cable with the second vtx yes? Use that to try and power the vtx from a proper source, then if either work you'll know the solder join has gone bad on the flight controller. It might have even pulled the pad off but just isn't noticeable, usually there is another 5v (or what's needed) you can move it to, I think I've had to move my vtx power about six times now lol.
 

kpixels

Antigravity or bust...
#8
If your other (dead) VTX has it's own antenna lead, try swapping them. If you don't have an extra antenna lead then try gripping the antenna lead wire with one hand and then the antenna jack with your other hand and lightly push together and then tug a bit to see if that reproduces the problem. I had a crash once and my VTX escaped it's mounting (zip tie) and slammed forward. The wire separated from the jack under the shrink wrap so I couldn't see it. After the crash everything looked fine so I went back up, but video feed was so bad that I was just barely able to fly it back and land. Trying to figure out what was broke had me stumped until I accidentally tugged on the wire and it pulled out from the jack.
 

kpixels

Antigravity or bust...
#10
The vtx doesn't power up unless he move the wires on the FC about so I don't think it's an antenna issue.
After reading this request for "help with troubleshooting" again, I would still offer the same advice. It sounds to me like this person is trying to explain that the video signal in the goggles changes when they move the VTX around. RSSI is Received Signal Strength Indicator which would have to be in the goggles OSD. Just trying to help tho.

from post #1
"After a drone crash i had to resolder my VTX back to my FC, i think it lost the connection due to some vibrations, since then my VTX sends no more RSSI signals to my FPV Goggles, my VTX powers up/ lights up and sends sometimes after clicking 100 buttons randomly and moving the antenna a video signal which is perfect, but after a small time i lose it again..."

from post #5
"If I move the Vtx, especially if I move it away from the drone, then it finds its channel, the right led's lights up and an RSSI signal is available and the video is perfect."
 
#11
After reading this request for "help with troubleshooting" again, I would still offer the same advice. It sounds to me like this person is trying to explain that the video signal in the goggles changes when they move the VTX around. RSSI is Received Signal Strength Indicator which would have to be in the goggles OSD. Just trying to help tho.

from post #1
"After a drone crash i had to resolder my VTX back to my FC, i think it lost the connection due to some vibrations, since then my VTX sends no more RSSI signals to my FPV Goggles, my VTX powers up/ lights up and sends sometimes after clicking 100 buttons randomly and moving the antenna a video signal which is perfect, but after a small time i lose it again..."

from post #5
"If I move the Vtx, especially if I move it away from the drone, then it finds its channel, the right led's lights up and an RSSI signal is available and the video is perfect."

I'm sorry, but that rssi signal changes all the time, even if the vtx does not move, so it can not be due to the antenna right?

You got a cable with the second vtx yes? Use that to try and power the vtx from a proper source, then if either work you'll know the solder join has gone bad on the flight controller. It might have even pulled the pad off but just isn't noticeable, usually there is another 5v (or what's needed) you can move it to, I think I've had to move my vtx power about six times now lol.
I have a plug included for a 2s battery, but I have only 3s and 4s batteries and the first tutorials on Youtube how to connect the vtx with the camera without a FC did not look really trustworthy.
I have already ordered a new FC from China, but I would still like to learn how to get my vtx running with my camera and my 3s/ 4s battery. Maybe you have some tips or know a website or a video where it is explained nicely?
 

FDS

Well-known member
#12
You run the VTX off Vbatt on the PDB/ESC/FC, where ever has a labelled pad, if the loom looks like the picture below then cut off the JST connector and solder that to Vbatt and ground. What happens then is the power goes into the VTX as a filtered supply from the battery, then the VTX sends 5v to the camera via the camera plug. You then solder the Smart Audio lead and video in (Camera video) and video out (VTX video) wires to the FC as normal.
A8E99DD9-20D1-46D3-A445-98700BCD2EA0.jpeg
The un labelled plug is the one that goes into the VTX,
RSSI is done from the receiver connection to the FC, it has nothing to do with the video feed. You need to look in Betaflight and see which channel RSSI is transmitting on and set it up from there, Bardwell has a video. Otherwise you are using telemetry from the receiver to do the signal strength, which is set up in a Betaflight via ports tab and on your TX. I use that with voice alerts instead of the OSD, since it’s more accurate and you can set the alert where you want.
 

kpixels

Antigravity or bust...
#14
I'm sorry, but that rssi signal changes all the time, even if the vtx does not move, so it can not be due to the antenna right?
Some newer vtx like my Tramp HV can adjust the power output if the antenna is missing or messed up, to save from frying itself. Not saying that is your problem, just telling you what happened to me and that mine had similar symptoms. Mine was just bad antenna wire from crash but damage was not visible, antenna was fine. It's simple to test if you haven't yet.
 
#17
After I had installed my new FC with my new vtx it still had not worked, then I connected the volt connection directly to the battery and then it worked, but now I wonder why it was possible in the video.


I would be glad, if someone would explain to me, why he makes his VTX 7-24V connection to a 5v output and it works afterwards?
Minute: 30:50

At least everything works fine and i can enjoy flying
Huge thanks to everyone
 
#19
Hello!
I recently build my first Quad but i have some Problems with my Video/ VTX.
After a drone crash i had to resolder my VTX back to my FC, i think it lost the connection due to some vibrations, since then my VTX sends no more RSSI signals to my FPV Goggles, my VTX powers up/ lights up and sends sometimes after clicking 100 buttons randomly and moving the antenna a video signal which is perfect, but after a small time i lose it again, now i thought my vtx is broken so i bought a new one, but this time the VTX doesn't even power up (no lights/ nothing). Now i am confused and i have no idea where the problem could be, did i got an broken VTX?
Is my new VTX too good for the FC? I have no ideas.
FC: https://www.banggood.com/9_4g-30_5x...-OSD-5V-BEC-and-Current-Sensor-p-1226610.html

First Vtx which still works a little bit:
https://www.banggood.com/Mini-VTX58...Transmitter-Module-OSD-Control-p-1257034.html

New Vtx which looks dead:
https://www.banggood.com/Eachine-TX...mitter-Support-OSD-Configuring-p-1248768.html

I am really searching for help and i have no idea what to do next or where the problem could be (My drone is a mix from the UAV-Futures 99$ Build Base and Pro version)
 
#20
With your old vtx, check the antenna solder joint, it sounds like you are click the button on the board and a cold solder joint is making intermittent connection and it works but then as the board heats up it loses the connection, check all the solder joints. Also if you can get it to work again for a bit, after it stops press down on the IC’s and see of an IC has a bad connection. To me that board may be salvageable, depends on your level of experience with a soldering iron and reflowing IC’s. As for the new board not sure what you bought, but if the VTX is right and connects ok into your FC, it should work fine.