GP 1871F and TM260

[tkki1230]

Hi,

I'm currently running the 1871F with a TM260. I basically use the sounder for deep dropping between 600-1000 feet. The unit was working pretty good until I did a repower on my Whaler. I went from a Mercury 90 to a Suzuki 90, and that's when my problems started.

The unit now displays a lot more noise than before, and it frequently loses bottom. Sometimes I need to reboot the unit to get it working properly. This happens when the motor is running. When off, the unit is fine. The power goes direct to the battery, the ground goes to the factory location, and the transducer cables are clear of the motor control and power cables. I know it's not the unit because I run 2 of the 1871's, and both of them have the same problem when I switch the TM260 between the both of them. I use 1 1871 for the sounder, and the other for the chart. One has the TM260, and the other has a P66. Whatever unit that is running the P66 at the time DOES NOT have any issues with the sounder. It's just the unit/sounder that has the TM260.

The unit running the P66 always has the transmission set to OFF to avoid any interference to the unit with the TM260. The P66 is just a backup transducer.

That TM260 setup was working really good until the repower. Any suggestions?

 

[Johnny Electron]

Do you have some photos of what the TM260 looks like whenever you have the problem?

 

[tkki1230]

I don't have any photos, but next time I go out, I will take some shots.

 

[tkki1230]

Its been a while, but I'm back with an update if anyone is interested. I did a lot more testing, and I managed to solve the problem. The biggest culprit was the alternator noise coming from the Suzuki. It didn't show too much at 200kHz, mostly just at low frequency at 50kHz. The screen would light up with yellow lines when the motor was running with the gain at +30 and over. The unit would also cycle back and forth between the true bottom and false readings for at least a minute before being able to lock on.

I first tried a Newmar Noise Reduction filter, and that helped a little. I ended up disconnecting the aux battery fron the charging system. That fixed a lot of the problem. I then tried moving the shield ground wire to the engine battery negative terminal. Surprisingly, that also helped out quite a bit. Whatever remaining noise showing up was coming in thru the transducer. Some of it was from the engine, and some of it was from turbulence. I added on an additional 10 ft of transmission cable, and I added a Ferrite filter. This totally cleared up the screen, except for some turbulance problems that I couldn't figure out until my son pointed out to me that the transducer was coming out of the water on really rough days. I fixed that by MacGyvering the transducer mount so I could adjust the position of the unit a foot under the hull when it was rough. That worked out better than expected. I can now cruise in low frequency in 150 fathoms with a crystal clear screen.

Sorry I didn't take any pictures of the screen while going thru the process. Trying to take phone pics out in open water was much harder than anticipated.

 

[tkki1230]

Also, the unit does not lose bottom anymore. It finds bottom instantly. Highest speed at 50kHz with a clear speed with no drop outs is around 16-17 knots. This is with the transducer in the lowered position, which is about 11-12 inches below the transom on the port side of the engine. At 200kHz, screen is clear up to 28 knots. This is transducer in the up position, which is about 1/4-1/2 inch below the transom.

 

[Deep Blue]

tikki1230,

Well done..! I am glad to hear that you solved your noise issue(s) with your GP1871F & TM260, with good ole' fashioned trial and error troubleshooting. Hopefully more people who might be experiencing these same type of issues will read your posting and conduct that same type of troubleshooting that you have.

Excellent work.

- Deep Blue