Failed Auto Pilot

[Ole Hank]

I came off some pretty rough seas a few days back. Everything worked fine. The next day when I fired everything up the autopilot controls and AIS etc (2 small screens on lower helm and one on upper) did not power up. I looked at the ACU400 and found the 3 Amp fuse blown. I replaced it and it blew immediately. After talking with Ray Marine they suggested I remove the Seatalk and replace the fuse. If the power to the seatalk from the ACU400 was normal then it is not the ACU400 but likely a short somewhere, worn wire etc. I did this and the power from the unit is fine with the Seatalk disconnected. Blows fuse immediatly when connected. Has anyone had a similar problem and can point me in a probable problem location?

 

[twistedtree]

Sounds like a short in one of the seatalk attached devices, or the cabling itself. Try disconnecting devices from seatalk one at a time until you find the culprit.

 

[Alaskan Sea-Duction]

Sounds like a short in one of the seatalk attached devices, or the cabling itself. Try disconnecting devices from seatalk one at a time until you find the culprit.

I agree with TT and was going to suggest the same thing. The issue is indicating a short. Be aware that sometimes the SeaTalk backbone has more than one power supply connection based on how long your backbone is.

A wire may have come loose during the bad weather and shorting out....

 

[SOJOURN4]

Had a similar issue about 6 mos after delivery.
Traced to a Seatalk block under the upper helm station.
Block was secured directly to the fiberglass and subject to water intrusion.
This was blowing the BLUE end plugs (don't know the correct name)
Removed the block and installed a 3/4" azek block and all has been fine since.
As an FYI, this also affected the Fusion system since it is on the network

 

[Ole Hank]

Thanks this is exactly where I traced the problem to. What is an "Azek" block?

 

[SOJOURN4]

Composition board (Not wood)

I used 3M 5200 to secure the block, then screwed the Seatalk connector to the block just to get the Seatalk terminal block out of the waterline.

Was the network end fuse (blue) blown?