FCV-295 + TM275LHW weak returns on both HF and LF — wiring/settings check

[masonschulze]

Hi everyone,


I’m running a Furuno FCV-295 with an Airmar TM275LHW (Simrad/Lowrance cable version) and I’m having trouble getting strong returns.


The system is working, but both HF and LF are very weak and require high gain (around 9–10) to see bottom even in shallow water.


Current setup:


Transducer: TM275LHW
Sounder: FCV-295


Wiring


HF:
Blue → pin 3
Black → pin 1


LF:
Blue/White → pin 3
Black/White → pin 1


Temp:
White / Brown


Shield:
Both drain wires grounded to chassis screw


Orange / Purple pair currently not connected.


Settings


HF frequency: 200 kHz
LF frequency: 50 kHz
Transducer type: 50/200-1ST
Tx power: Auto


When testing on the water:

• Both HF and LF show bottom
• But the return is weak and requires very high gain

I also tried frequencies closer to the CHIRP band center (150 kHz / 38 kHz) but the unit threw a “transducer setting is not appropriate” warning.


Questions

1. Is the wiring correct for the Simrad version of the TM275 cable?
2. Should the orange/purple pair be used as HF instead of the blue/black pair?
3. Should both LF coils be paralleled on the FCV-295?
4. Is the correct configuration manual frequency (155 / 42) instead of the 50/200 preset?

Any advice from someone running a TM275 on a FCV-295 would be greatly appreciated.


Thanks!

 

[Deep Blue]

masonschulze,

Your transducer wiring and output power are correct. However, you still need to set the correct Tap Settings. You must select the Tap Settings for a the B275LHW is: HF "Tap A" and LF "Tap A". Please see the attached document.