DFF1 Problems



My husband and I have your DFF1 black box sounder attached to NavNet v2 on our Nordhavn. We have been having problems with the sounder not registering the bottom in depths over 200 feet. The sounder is displayed on both the 1944C/NT radar and chart plotter display and the 1834CBBNT20 black box radar attached to a flat screen PC monitor through an ethernet network.

When the sounder is used in shallow water it seems fine. As we move into deeper water (100-200 feet) the display becomes intermittent and finally goes completely blank. As we move deeper into water over 200 feet the depth is sometimes displayed (numbers only) randomly. Example: -----, 3.5, 147, 328, 12, 36, etc. This problem occurs both on high frequency and low frequency. It renders the sounder useless as we can no longer trust it to display a warning of rocks or reefs.

We are trying to determine if:
1) a setting is wrong - we have it set for Cruising mode with auto gain - or
2) the DFF1 is faulty or
3) if the transducer (Furuno 525ST-MSD7 600E) is bad.

Is there a way for me to check?

We are currently cruising in Mexico and are staying in Marina de La Paz until spring.

Linda Penwarden
N46-37 MV Discovery
If this problem is something that has recently developed; I would suspect the transducer. It is very uncommon to have a problem with the DFF1. When it comes to your depth, make sure you are looking at the sounder depth and not another source of depth on the boat. Many times on a boat like yours, there will be a NMEA smart depth transducer. It is normal for them to lose depth about 200 ft. Is it possible that your depth is from a NMEA smart transducer? (Check your data source: MENU - SYSTEM CONFIG - NAV OPTION - NAV SOURCE SETTINGS) If your depth source is ETR then it is your DFF1 sounder. If it says NMEA, then it is looking at something else. If it is set to ETR then I would recommend you try a reset of the sounder to factory defaults. (MENU - SYSTEM CONFIG - SYSTEM SETUP - TEST & CLEAR - MEMORY CLEAR - NETWORK SOUNDER = YES) If the above advice doesn't clear your problem and it used to work fine; then I would highly suspect a transducer issue. Did anyone recently paint the bottom of the boat? (Painted transducer by mistake) Has anyone checked the transducer for marine growth?
Thank you for your quick reply. We checked on the settings you mentioned. The sounder source is ETR. We reset the sounder to the factory defaults. Unfortunately we are in a marina and cannot check to see if this helps, but will as soon as possible. The problem is not a new one. It started shortly after we installed the new equipment and has been getting worse over the last 3 years. It has not been painted and we do have the bottom cleaned regularly. I will let you know the results when we go out and test it. Thank you again.

Linda Penwarden
N46 Discovery
Yes, please let us know. If you had problems from the beginning, it could be an installation issue. Are you running a 1KW or 600w transducer?
We have a Furuno 525ST-MSD7 600E Transducer. I'm guessing that's 600W. At the very beginning it seemed to work better, but never as good as I thought it would be. Slowly over time it has gotten worse and worse until now it's almost useless.

Linda Penwarden
N46 Discovery
Please check that the MODE switches under the rubber grommet on the DFF1. It will have four switches. The first and last should be down and the middle two should be up. If you are brave enough, you could also take off the cover and look at the circuit board of the DFF1. Straight up from the (RJ45) network cable connection, about ¾ up the board you will see a small four position surface mount switch. It will look like a small computer chip with switches on it. The top of the switches (all 4) should all be away from the cables, and not towards them. If the mode switches and the circuit board switches are good, I would suspect that the transducer is getting water turbulence. The transducer was new, correct? You can always send the sounder in for testing if you wish, but the odds are the transducer has a problem. It might be that the location it was installed isn’t allowing for clear water. If after checking and resetting, it still doesn’t work well; try stopping the boat and letting the water settle. Once the water has settled, see if you get good bottom and depth. If it works good sitting still and not moving, it is almost certainly a water turbulence issue. Your transducer might need to be moved to a more suitable location. Let us know your findings.
Thank you again for your help. We checked both sets of switches and they are in the positions where they should be.

Another possibility is that next to this transducer is another transducer attached to our Airmar PB-100 weather station. This is a Smart Sensor 235DST. It is my understanding that they are on different frequencies and should not interfere with each other.

We will check out the turbulence idea next time we're out. I will let you know at that time.

Linda Penwarden
N46 Discovery
I am seeing the same issue as described here.

The DFF1 was installed with the yacht build from new. The initial unit worked very well for 4 years then started to not display depth (but continued to show video images). Changing the "Bottom level slightly" [Sounder System Setup -> Bottom Level HF/LF] corrected this for a short period but the numerical depth failed to show up at progressively shallower depths in clear water.

For example, initially in LF mode the sounder showed the bottom and produced depth down to 500m. Once this problem started the depth did not show below 100m then 50m then 20m. While this was happening the video picture also faded requiring the gain to be wound higher and higher to view an image of the bottom. This was not a transducer problem as I have 2 600W transducers in the hull: 1 active and 1 as a permanent backup. Both were clear and clean. It was also not a turbulence problem either as this continued even when the yacht was at anchor.

Finally the DFF1 unit failed altogether. After talking to Furuno in the USA I purchased a new DFF1. The old DFF1 was DHL couriered to Furuno in the USA for testing - and I never heard anything back about it again. The new DFF1 has worked perfectly for the last 2 years (with the original transducers). I now have exactly the same problem again.

All the DFF1 DIP switches (externally and on the circuit board) are in the correct positions. I have tried doing a "Memory Clear" on the Network Sounder but this makes no difference. Any suggestions?
Strange to hear that you had issues with two modules. Do you have the serial number of the first one you sent in? Normally what you are describing is more transducer related than the DFF1. Are you in an area where you can get another transducer to hang over the side to test?

Hi Snips,
I am now on my third DFF1 which has just failed again - but in a different way this time. It is now failing to connect to the Navnet network.
Here is what I am seeing...
- The network and hub are fine as I can see other devices across the network and communicate with these
- The ethernet cable to connect from the hub to the DFF1 is also fine as this works for other devices
- The port on the hub is fine as this can also be used for other devices
- Connecting direct from my1944CBB to the DFF1 produces the same result
- On the DFF1 the status indicator light blinks once and stays on - indicating a failure to communicate with the Navnet hub
- Its not the transducer as I have 2 working transducers in the hull and I get the same result with either or none of these plugged into the DFF1.
- On the DFF1 next to the ethernet port there is a transmit and receive LED indicator. The receive indicator blinks in a manner that looks like realistic network communication (that increases when I run a radar picture across the network) but the transmit LED stays on permanently.
- Trying to ping the DFF1 across the network or poll it with Wirehark produces no response from the unit
Is it just me or is the DFF! a particularly unreliable item of equipment?
I see the DFF1 has been phased out by Furunno - they seem to recommend replacing it with the BBDS1. Has anyoone had reliablity issues with BBDS1. I am not particularly keen to buy yet another expensive and unreliable item of equipment from Furuno.
Thank you for detailed description.
Interesting to hear. I would be curious to hear what happened to the first two DFF1 modules, did you send them into a service center for evaluation? The track record for the DFF1 has been pretty solid and to have three of them act up on one vessel leads me to think something else is going on. Was this last one a new unit and are you located in the US?