M1931 radar

[Nick]

Hello everyone,
I have a question about the older Furuno radar M1931. Purchased like used one. When everything was connected and turned on, it was noticed that the GAIN was not working. Otherwise, the echoes are strong and boldly drawn on display. I looked in the operation manual, and according to the block diagram, seems that the problem cannot be in the scanner, but only in the display. This radar type does not have separate wires for gain and stc, all echo processing is in the display, right? So it can be anything from a gain potentiometer to a processor pcb, right?
I just want to check my thoughts.

Thanks
Nick

 

[Johnny Electron]

You are spot on. The 1931 (yr 1993-1995) is a logarithmic processed video in the display using the older 32v tuning voltage ramp of older systems. The problem does indeed sound like something in the display unit.

 

[Nick]

Yes, thank You Johnny!