Resuscitating an ST50

[prv]

I suspect I know the answer here, but thought it would ask just in case. Is there any secret knowledge about resurrecting a "dead" Raymarine ST50 instrument? Perhaps a fuse inside that can be replaced, or a reset sequence on the buttons?

The fatal event was my dad managing to put a screw through the seatalk cable, short-circuiting it enough to give off a burning smell and making the moulding the wire was running through warm to the touch. I guess we're lucky it didn't actually catch fire. At the same time, the needle on the instrument was jerking around randomly. Now, having fixed everything and replaced the cable, the instrument appears dead - no movement of the needle and no display in the LCD window.

It's had it, hasn't it.

Pete

 

[nigelmercier]

Was this the SeaTalk cable that powers it, or the outgoing loop? Are there other instruments in the loop, and are they working?

 

[prv]

It was the cable into the hatch garage, where this instrument (a compass display) was mounted along with two others. Not sure what the actual sequence of connections inside the garage was, or whether the other instruments are now working. We cut and spliced the bus either side of its loop into and out of the garage in an attempt to get the other instruments elsewhere working, so for the moment everything in the garage is disconnected. I took the compass out (and have brought it home) to see if it survived, and so far the answer seems to be no.

Pete

 

[prv]

Ok, the answer is definitely and finally no. The only way to be more "no" would have required a fire extinguisher. I've just taken the back off the instrument and here's the inside: http://i1168.photobucket.com/albums...E6C219-11508-00000EF459DF159D_zps0a984cc4.jpg

Have to say, I have no idea how putting a screw through the cable could have caused that. It looks more like the thing was accidentally connected to the mains! But apparently it did, because the display was working not long before.

Not much point continuing this thread now, really

Pete

 

[nigelmercier]

ONot much point continuing this thread now, really

It certainly looks like it has had it. You may want to check that the power feed to your instruments has a suitable fuse.

The good news is that the case is ideal to house a YAPP project in

 

[prv]

It certainly looks like it has had it. You may want to check that the power feed to your instruments has a suitable fuse.

Indeed. There is a breaker as originally installed by the builder, but I don't know what rating it is. I think (think - the wiring is a horrible spaghetti due for replacement next winter) that it also supplies the autopilot, so probably quite large. But of course the pilot is powering the seatalk bus anyway, as often recommended. Does the pilot have a fuse on its outgoing seatalk supply?

Pete

 

[nigelmercier]

But of course the pilot is powering the seatalk bus anyway, as often recommended. Does the pilot have a fuse on its outgoing seatalk supply?

That is a very good point. I disconnected the breaker on my autopilot once, and the instruments continued to work. It is therefore likely that I power mine from both ends of the loop, which is fine. However, the instruments are on a separate fuse, so the autopilot power output must be switched (and one hopes fused) internally.

 

[misterg]

That is a very good point. I disconnected the breaker on my autopilot once, and the instruments continued to work. It is therefore likely that I power mine from both ends of the loop, which is fine. However, the instruments are on a separate fuse, so the autopilot power output must be switched (and one hopes fused) internally.

Are you sure the Seatalk power is connected at the autopilot? IIRC the diagram in my Raymarine manual shows just signal & ground of the ST bus connected at the autopilot, with the autopilot being powered from its own fuse and the instruments powered from another (smaller) fuse from the "other end" of the ST bus.

 

[prv]

Are you sure the Seatalk power is connected at the autopilot? IIRC the diagram in my Raymarine manual shows just signal & ground of the ST bus connected at the autopilot, with the autopilot being powered from its own fuse and the instruments powered from another (smaller) fuse from the "other end" of the ST bus.

Either way is possible. In my case (having looked at it yesterday when rejigging the system to route around the damage) the seatalk bus is connected to power at the autopilot.

Pete

 

[nigelmercier]

Are you sure the Seatalk power is connected at the autopilot? IIRC the diagram in my Raymarine manual shows just signal & ground of the ST bus connected at the autopilot, with the autopilot being powered from its own fuse and the instruments powered from another (smaller) fuse from the "other end" of the ST bus.

I'm not 100% sure, no. But in the manual I just looked at there are two 3-way SeaTalk terminals on the autopilot. This is obviously something worth investigating, as the SeaTalk bus should ideally be a ring, at least for power.

 

[prv]

the SeaTalk bus should ideally be a ring, at least for power.

Not normally, according to the manual. Just a straight bus. It does say you need to add power from the other end if you have more than 13 instruments on a 10m bus (which ought to cover the average cockpit area).

Pete