Furuno 1720 radar

I have a 1720 Furuno radar. The 5 amp fuse , located on the rear of the display unit blows when the Scanner is connected. I measured the connector pins 2 and 3 on the connector that plugs into the scanner unit. There is 12 volt there. I then unplugged all the modules thta get their power from the modulator unit. My idea was to see if the fuse would blow with all connections from the modulator board disconnected. It blew.

The unit operated correctly since I purchased it new. The last time I trailered the boat, the radar scanner hold down came lose and the scanner was held from droping by the cable. I checked the connector and cnnot find any problem. I placed an ohmeter on pins 3 and 3 and measured 3.8 ohms. This seems to be within the ball park for a 5 amp fuse. Any ideas what it can be? Where are you located? Really can't afford to buy a new radar at this time,