Hi,
I bought the new thin 4mm diameter tether with the only one pair of cables inside, 100m. Its no rocket science to install this new cable to the fathom spool, the ROV and the tether box. But somethings wrong: The old 8wired tether works fine. Only the blue/white pair of wires are in use. The old tether has about 75m length.
With the new 2wired tether theres no connection possible. We checked everything, the plugs, the solderings, polarity, resistance, USB power and we rolled out the whole cable in the backyard to avoid interferences. We cut off 30cm of the new cable and built this part as a tether for checking and it worked. We reinstalled the brandnew 100m and still no connection. The electrical tester device said there is a proper connection from the topside tether interface board to the board on the ROV on both wires with about 16 ohms (the old cable has about 11 ohms at 75m). No short circuit, and the tether interface works well with the old and the super short new cable.
Do I need the Fathom X Interface Box to get the new cable work? A couple of years ago when I bought the ROV the tether interface was delivered blank, without any housing, only the board. Maybe this interface is too weak or something like this to serve 100m tether? I have no idea anymore where to look for the problem. Only two simple wires to connect and we got perplexed…
Hi @schleitaucher -
Sorry for the hassle! The 16 ohms you measure seems about right given the 100m length and specification for the tether resistance per meter.
How are you powering the two Fathom-X interfaces?
Where did you purchase the tether interface without a housing? The BlueROV2 has included a case for this hardware for considerably longer than 2-3 years…
The ROV side gets power directly from the battery, but the topside requires either USB power or 7-26V DC. If you don’t have a solid green link light on both the Fathom-X units, no connection is being made for the ethernet ports. Should this be the case, one of the homeplug modules could have a fault.
If you’re able to reach the BlueOS interface via the BlueOS WiFi hotspot or the IP address of the vehicle connected to your local WiFI network, you can install the tether diagnostic extension and see what the system is able to learn from the Fathom-X unit in the ROV.
Interestingly - the polarity of the connection between the two Fathom-X boards does not matter!
Please reach out via our support form if the issue persists!
Hi Tony,
thanks a lot for the fast reply! I purchased the BlueROV2 straight from Bluerobotics in 2018. In the meantime there is a dealer at Hamburg here in Germany where I get my spareparts and additional Equipment.
Usually we power it over a USB port from the topside computer and we also tried an 1 ampere USB charger. The ROV side gets its power from the battery which is in good condition.The tether interface shows both lamps at the plug on but not really busy. If I connect the old cable the flickering LEDs shows more activity and a few seconds later the connection to QGC or Cockpit works. It seems to me that the hardware is OK.
I didnt get a connection to BlueOS over 192.168.2.2 with the new cable.
Hi @schleitaucher -
I should have been more clear - the light I’m talking about isn’t the one on the ethernet jack, but the Link light labeled on the FXTI PCB. It is not lit up, so the homeplug adapters have not been able to establish a connection for ethernet traffic…
If you verify the resistance from board to board is only ~16ohms per connection, one of your Fathom-X modules has likely failed…
Thanks a lot! I checked the resistances once again: The old tether has 24 ohms at 75m length. The new cable has 19 ohms from board to board on every single wire.
I’m wondering why the old cable works with the boards. The attached pictures are made a few minutes ago.
I will contact my dealer, perhaps he can provide a topside fathom box for testing.
Hi again,
I found the error.
The small board with LX200V20 written on it, wasn’t plugged in properly.
After giving it a little pressure on top, it plugged in all the way and the new cable works at full lenght.
I still don’t know why the old cable worked with this semi-plugged board.
However, thanks a lot for the fast support!!
