DFF1 no lights on TZT2


New member
We recently upgraded from Navnet3D to TZT2. We kept the same DFF1 with 1kw transducer and Hub101 we had with the Navnets, they were all working fine. During first sea trial we had no bottom reading. Thru another post we were recommended to replace the Hub101 with a locally bought Netgear unmanaged 12V switch since our Hub101 was marked "11" meaning it was too old.

We did this, used a Netgear GS108, we uploaded central america charts, we turned on some NMEA2000 outputs so that the new autopilot can follow a waypoint, we are all good with all of that, TZT2s turn both off with the network option, so it all seems to be good.

Here is the issue, DFF1 does not turn on, no blinking or solid lights, unit has power on the power plug and i checked inside and power is present in a couple of wires that i tested that come from the little board with the power input and go to the main board, but there are no lights, not even on the Netgear switch port, as if the DFF1 was completely dead.

I was looking for a DFF1 online and came across some used ones that in the description say this:

This DFF1 was UPDATED to Furuno’s latest software (V3.01) and is compatible with current models; for example: TZTs and other Navnet Models.

PLEASE NOTE: Software version 3.01 adds a Post Processing Gain feature for TZT2 using v6 or higher

Could you guys please help me out with this? Are we talking about a software issue? Does the TZT2, thru software, order the DFF1 to turn on and this is what is not happening? DFF1 is just as old as the HUB101 that was too old, DFF1 serial number is 8858-8577, has a sticker that says 2013 on it. Can the DFF1 software be upgraded by us users if that was needed? Or is the best option getting a new sounder box, which is what we are trying to avoid.

Thank you all in advance for any help you can give me with this.


My guess is the MODE Switches on the DFF1 are still setup for NN3D power sync and it won't turn on. Change the MODE switches at the front of the unit to DOWN, UP, UP, DOWN. That should allow the device to power on and work.