No Signal? Find the failed stage.
Start at the camera, follow the picture through TX, the wireless link and RX, then check the display. Camera and gimbal control are separate paths.
60-second symptom check
Do not change every setting at once. Find the last point where the system behaves normally, then test the next connection.
| What you see | First place to test |
|---|---|
| TX or RX will not power on | NP-F voltage, USB-C PD source, or the exact Ronin power/control cable and port |
| TX says No Signal | Camera's actual output format and camera-to-TX video cable |
| TX sees video; RX cannot find TX | TX/RX roles, Search Devices, password, previous link and eight-RX limit |
| TX/RX connected; monitor black | RX resolution/fps/bitrate, then RX output, cable and monitor format |
| 1080p works; 4K does not | Actual 4K output format and whether the path uses the main unit or Expansion Plate |
| Picture works; camera parameters do not | Camera-specific PTP/CEC support, control connection and camera settings |
| Ronin app opens; no view | RX stream data, USB/DP data cable and USB Adaptive mode |
| Picture drops or connects to wrong camera | Channel quality/occupancy or TX device number A–P |
Follow the video chain before touching the control chain
- No TX power? Isolate the power source before video or RF.
- TX says No Signal? Check camera output and input cable.
- RX cannot connect? Check role, device discovery, password and capacity.
- RX connects but shows no stream data? Recheck TX video status and link.
- RX shows stream data, monitor black? Test RX output, cable and monitor.
- Picture works, controls do not? Move to the separate camera/RS control paths.
The decision tree is an editorial fault-isolation method based on DJI's receiver-screen checks; it is not a promise that one observation proves every other component healthy.
TX shows “No Signal”
Check what the camera is actually outputting—not merely its internal recording setting. DJI lists DCI 4K, UHD 4K and 1080p at 23.98 through 60 fps for SDR Transmission 2, plus specified 1080i and 720p inputs. Its recommended sequence is supported source format, securely seated cable, then a different cable. Do not apply the first-generation SDR transmitter's 1080p-or-lower troubleshooting instruction to SDR 2.
For a controlled baseline, temporarily set the camera's external feed to 1080p60 SDR and retest. This is SpeedyDrone's diagnostic suggestion, not a DJI-required operating mode. If that feed appears, return to the intended 4K output one variable at a time: resolution, frame rate, HDR/output setting and cable. A working 1080p feed does not certify that the full path supports the desired 4K signal.
Practical question: Does TX itself detect the picture? If no, pairing RX again cannot repair the camera-to-TX input path.
TX has video, but RX cannot find it
Confirm the camera-side unit is set to TX and the viewing-side unit to RX. On RX, use Search Devices, select the intended TX letter and enter its four-digit password if Password Lock is enabled. A TX can be assigned a letter from A to P; those letters help a multi-camera crew pick the correct source.
If the target is absent, check that it is powered and nearby. DJI notes that an RX already linked to a distant TX may not discover another nearby unit: disconnect that old link, then search again. If you see a connection-limit message, one TX supports up to eight RX units; a ninth connection is not automatically a failed receiver.
The hardware in DJI's illustration makes the multi-receiver topology visible; it does not depict a real connection fault.
TX and RX are linked, but the monitor is black
Look at the RX screen before replacing the camera cable. DJI says an RX receiving video normally displays resolution, frame rate and bitrate. If those fields appear, the radio/video path is producing a stream; check the selected monitor input, RX output connection, cable seating or substitute cable, and whether that monitor accepts the transmitted format.
If those fields do not appear, “connected” does not mean “receiving usable video.” DJI directs you back to the video-status icon on TX. Confirm TX still sees the source, then inspect the wireless connection. This difference keeps a display fault from being misdiagnosed as a camera fault—and vice versa.
Fast branch: RX stream data visible + display black → investigate output/display. RX stream data missing → return to TX status/link.
1080p works, but 4K does not
The SDR 2 main transceiver supports listed DCI and UHD 4K source rates through 60 fps. That does not mean every menu item labelled “4K” on every camera will be sent in a compatible external output format. Verify the actual HDMI or DP output resolution/frame rate, change one camera-output setting at a time, test the video cable, and make sure the receiving display accepts that format.
HDMI 4K works, but SDI 4K does not
This may be a specification limit, not a fault. DJI explicitly says the SDR Transmission 2 Expansion Plate does not support 4K input or output. Moving from a working main-unit HDMI/DP path to an Expansion Plate SDI path changes the supported format. Do not replace a healthy transceiver in pursuit of 4K SDI through this plate.
Remember: The Expansion Plate adds SDI connectivity; it does not create a 4K SDI workflow.
Video works, but camera control does not
ISO, shutter or aperture is missing
Video compatibility and PTP control compatibility are different. Verify the exact camera and desired function in the SDR 2 camera compatibility guide and DJI's current matrix. Then inspect the chosen camera-control cable/path, camera USB/remote setting and operating mode. Test one parameter, then photo or record trigger. DJI cautions that functions depend on the camera.
Mirror Control or CEC is missing
A valid HDMI picture does not establish CEC/Mirror Control support. Check the exact model's CEC entry, camera HDMI/control menu and the relevant connection path. Do not treat PTP and CEC as interchangeable labels or promise that an HDMI cable alone enables both.
Ronin moves; camera parameters are absent
The TX-to-gimbal control path can work while the separate camera-control path does not. For an RS-integrated rig, inspect the appropriate camera-to-RS control cable and supported camera settings. For a direct camera-to-TX control workflow, inspect that distinct cable/path instead; the two topologies should not be conflated.
Video is stable; remote gimbal control is absent
Leave the camera video path alone. Check the model-specific Ronin-to-TX cable and port, TX communication and RX/app control path. The RS 5 / RS 4 Pro integration guide contains the full wiring diagram.
SDR 2 will not power on from NP-F, USB-C or Ronin
NP-F: Check charge/voltage and adapter seating; DJI cites insufficient NP-F voltage as a possible startup cause. USB-C: Use a compatible 65 W-or-higher USB-C PD adapter on the power input, not merely a supply with a large printed wattage. Ronin: Check the exact model's cable and port before touching the RF settings.
RS 5 will not power or communicate with TX
Without an Expansion Plate, DJI specifies the included firmware-update USB-C cable from TX USB/DP to the RS 5 Multifunctional Port. With the plate, the RS 5 connection moves to the plate's side port. Check the gimbal battery, cable seating and port.
RS 4 Pro will not power or communicate with TX
RS 4 Pro (also RS 4/RS 3 Pro) requires the separately sold DJI SDR Transmission 2 Gimbal Control Cable (USB-C to CAN), not an ordinary USB-C lead. Without the plate, connect its labelled USB-C end to TX USB/DP and CAN end to the gimbal's Video Transmission/LiDAR Range Finder port. With the plate, connect the USB-C end to a bottom plate port—not the RS 5-only side port. This is a fault check, not a substitute for the detailed gimbal setup guide.
Ronin app opens but shows no camera view
First check whether RX itself lists resolution, frame rate and bitrate. If not, return to the TX/link diagnosis above. If RX has a stream, DJI's SDR 2 procedure is: connect the mobile device by a data-capable cable to the RX USB/DP port, select USB Adaptive on RX and open the DJI Ronin app. A charge-only cable or power-only port is not that data path. If video appears in the app but camera parameters do not, switch to the camera-control checks—not RF channel changes.
Signal drops, freezes or lands on the wrong camera
Start with DJI's default Auto Channel mode. Inspect channel quality, occupancy and conflict information while the rig is in its actual shooting position. Remove obvious line-of-sight obstructions, keep the TX antennas clear of metal rigging and retest before selecting a Manual channel. Manual can help a crew following a deliberate RF plan; it is not a universal cure and no range is guaranteed in a crowded location.
For several SDR 2 systems, assign TX device numbers A–P and label your own crew plan (for example A-cam = A, B-cam = B). Select the intended device from the RX list. That naming convention is a practical editorial suggestion, not a DJI-required scheme.
When should you stop troubleshooting?
Record the camera's actual supported output, test a known-good video cable, verify TX/RX roles and power, and note whether RX displays video-stream data. If TX still reports No Signal with a supported source and cable checks completed, DJI directs users to submit the device for testing/repair. Bring these observations to support; repeated blind resets do not add diagnostic information.
Need first-time connection instructions instead? Use the published SDR Transmission 2 Setup Guide. Need exact model-level control expectations? Use the camera compatibility guide.
Parts and links for a verified SDR 2 setup
If you are building a new two-ended link, the DJI SDR Transmission 2 Combo at SpeedyDrone contains two TX/RX-switchable transceivers. For an additional viewing position or a replacement in an existing SDR 2 system, the single SDR Transmission 2 transceiver is the relevant listing. If your rig specifically needs SDI and cage/mounting parts, review the SDR 2 Expansion Accessory Kit—while keeping its no-4K input/output limit in mind. Power, video, display and RS 4 Pro control-cable needs must be checked separately. Confirm current availability before a time-critical shoot.
SDR Transmission 2 troubleshooting FAQ
Why does SDR Transmission 2 say No Signal?
Check the camera's actual external output format against DJI's SDR 2 supported formats, then reseat or substitute the camera-to-TX video cable. Do not apply the first-generation transmitter's 1080p-only troubleshooting limit to SDR 2.
Why are TX and RX connected but my monitor is black?
See whether RX shows resolution, frame rate and bitrate. If it does, test RX output, cable, monitor input and supported display format. If not, inspect the TX video-status icon and the link.
Why can't I get 4K over the SDR 2 Expansion Plate's SDI connection?
DJI says the SDR Transmission 2 Expansion Plate does not support 4K input or output. Use a supported main-transceiver HDMI/DP 4K workflow if your camera and display also support the selected format.
Why can I see video but not change ISO or aperture?
Video and camera control are separate capabilities. Check your exact camera's PTP support, control cable/path, camera remote settings and the individual function you need.
Why won't RS 4 Pro power the SDR 2 transmitter?
RS 4 Pro requires the dedicated SDR 2 USB-C-to-CAN Gimbal Control Cable and the correct gimbal video-transmission/LiDAR port. With an Expansion Plate, use a bottom USB-C port, not its RS 5 side port.
Why can't RX find the TX?
Confirm one TX and one RX, use Search Devices, select the correct TX letter and enter the four-digit password if enabled. Disconnect any previous distant TX link; a TX at its eight-RX limit cannot accept another receiver.
What USB-C power adapter should I use?
DJI's startup guidance specifies a compatible USB-C PD adapter rated 65 W or higher. Also check the correct power input and cable rather than judging the adapter from wattage alone.
Tell us which stage fails.
Send SpeedyDrone your camera, monitor, gimbal, actual output format and the last working point—TX input, RX connection, RX stream data or display. We can help you review the relevant SDR 2 gear and cable plan for your Canadian setup.
Ask SpeedyDrone about your SDR 2 rig →Documentation scope: DJI's No Signal, monitor display, channel and device, power, Ronin compatibility and camera control guidance, checked 21 September 2026. Source-backed limits are distinguished from our suggested isolation tests. No hands-on repair result is claimed.
