1931 MKII with FMD 811

[Polaris1]

I recently purchased a boat that has a 1931 MKII radar on the bridge that works fine and an FMD 811 remote unit down below. The 1931 works fine but the FMD 811 would not turn on. I thought is was a bad unit so purchased another on eBay but it also would not turn on. Then I tried unplugging connectors and found both would turn on if I unplugged the interface cable plugged into DJ-1. If the cable was plugged in again the unit would turn off. The equipment seems to have been professionally installed but it's not clear if they we ever tested together.

Is there something simple I am missing? From the cable diagram, only HDG, BNG, TRIG & Video are brought down from the radar unit. I can't understand what might be wrong.

Any suggestions? Thanks in advance.

Don McCook

 

[Johnny Electron]

Don,

It sounds like a short is happening someplace. I would guess that it is in the slave inferface cable between the 1931Mk2 and the FMD811. When the FMD811 display feels the electrical short, it refuses to power on and let the smoke out. It is protecting itself from damage. The short could be in the circuits of that part the 1931mk2 but unlikely. I would disconnect the interconnection cable at both ends and use a meter to ohm each wire and ensure none of them are connected to each other (shorting to each other). Lastly, I would also check between boat ground and the wires of the cable to ensure no one has driven a screw through the cable someplace.

Johnny

 

[Polaris1]

Thank you very much. I’ll give that a try and let you know.