1712 Missing Heading Signal After A Few Minutes

[fourlyons]

Hello,

Recently my 1712 radar started misbehaving. It works well for anywhere between 2-30 minutes then seems to lose the heading pulse (if that's the right term). It continues to sweep, but the return gets painted as a circle around the boat. If it's a large return then the line is thick, a small return is a thin line. The magnetron is still turning, you can see the sweep updating. And I get an error code on the screen, "HD-SIG-MISS".

I have replaced the cable from the dome to the display, I found some damage to the insulation on the cable. When that didn't help, I found a replacement reed relay on a vendor's shelf and tried that. Still same problem.

I know it's an old radar but I really like it and there's only about 1200 hours on it. Any other things I should try? Maybe the MIC? I have enough electrical repair experience to handle simpler repairs.

I am going to start another thread about upgrading so please don't suggest that here, thanks.

 

[Titanic II]

Ensure the magnet is on one side of the array on the bottom. The magnet needs to come in close proximity to the reed switch when the array is facing zero degrees forward. With power removed follow the two wires from the switch to the connector jack, put your meter leads across the connector with it connected. You should read approx. 300 when the switch is made and an open when not made.

 

[fourlyons]

Thanks for the reply. I did check to make sure the magnet was there when I replaced the reed switch. But also, if the magnet had fallen off I don't think the radar would work for a while then lose the heading signal. It's like something is heating up then failing, then working again after coolin off. I just don't know enough about the unit to know which component that might be.