[CA] [CA11] Smart Pilot melted 2A fuse, blown board

[rickgard]

hello Raymarine forum
I have a 2007 Ray system which has performed flawlessly until I powered it up for the first time after winter lay-up. e80s work, Raystar works, radio, depth are good- but the st8002 pilot screen was blank. Further investigation of the Smart Pilot found the 2A SeaTalk fuse melted to the board and at least 25% of the components near the fuse burned completely away.

I found a used Smart Pilot S1 to replace the blown unit but before I replace it I want to know that I won't blow the replacement as well. I would grateful to know what to check and where.

My system:
two e80 (one connected to radar, one running the chart chips)
st8002 pilot head
Smart Pilot S1
rudder indicator, fluxgate, linear drive
Raystar gps

the e80s are working, but don't receive GPS fix, nor do they receive Rudder Position data for a data box.
the pilot head is blank, seemingly no power.

If I disconnect the SeaTalk 3 pin cable from the Pilot head then the e80s get GPS fix and operate as usual. still no Rudder position data in the e80 databox.

Reconnecting the SeaTalk cable at the pilot head, then check what is coming to the Smart Pilot SeaTalk Red/Yellow/Shield pins from the pilot head and found:

SeaTalk red to SeaTalk shield = 0v
SeaTalk red to ship's ground = 0v
SeaTalk red to SeaTalk yellow = 11.7v

SeaTalk yellow to SeaTalk shell 11.7v
SeaTalk yellow to ship's ground= 11.69v

SeaTalk shield to ship's ground = 0v

the SeaTalk red was connected to the terminal on the Smart Pilot - I mention this because reading through posts on the forums I found that should not be the case when the smart pilot is powered. My e80s, VHF, Raystar are all powered on one breaker, and the autopilot is powered on a separate breaker.

the pilot head SeaTalk cable input does include spliced wires from one e80. I guess this supplies data bidirectionally for the follow function as well as supplying the Raystar data.