I have now figured out the cable from main tube to battery tube is the problem.
Power cables and signal cables is same cable,sow you will get disturbance from power cables 75 volt.
Need to use shielded cable or two separate cables.
I have now try to use a shielded cable with Power cables and signal cables in same cable but is not working,once you connect 75 volts the SOS Leak Sensor board shows red light,remove the 75 volts, is working
Solution is to use two separate cables.
Fathom-X Tether Interface Board will NOT work with 75 volt DC in same wires.
(I use seabotix Tether 8.9mm all 6 wires is shielded)
I did a bandwidth testing and i get 60 upload and 18 download with 75 volt DC in same wires use to Fathom-X Tether Interface Board.
When i use two wires to 75 volt power and two wires to Fathom-X i get 60 upload and 75 download.
So need to be own cables to power 75 volt and to Fathom-X (shielded)
This also resolved the red light on the SOS leak sensor board, is working now in the battery tube.
Will test a little bit more