ST60 Wind Query

[DannyB]

My ST60+ is just showing 0.0 although if I push the true/app button it shows boat speed.
I disconnected the cable in the j/b at the bottom of the mast and checked the voltages. I'm getting 8V on red and the correct sort of voltages on blue and green, but on yellow I'm getting several hundred mV, which will occasionally flick to V but too fast to read a value on the digital meter. I've done the self test on the instrument and it seems happy until it gets to t4 when it comes up with F03. Faulty anemometer. So everything points to the mast head unit, but here's the thing, when checking voltages in the j/b I discovered that on the cable from the instrument I had 8V on the yellow core, as well as the red one. Could it be that there is a fault in the instrument which has damaged the anemometer? I'm reluctant to stick a new anemometer on if I risk damaging it.
Does anybody know what, if any, voltage should be on the instrument yellow wire ? I've drawn a blank with Mr. Google so far.
Curiously when I disconnect the mast head unit the display changes to three dashes, so it obviously knows the MHU is there, but thinks it is faulty.

 

[earlybird]

The Raymarine advice is to test for 0-5 volts between yellow and shield with the wires still connected at the j/b,
Volts vary with wind speed of course.

 

[Minchsailor]

I had an awkward problem with my ST60 and did a lot of digging around. There is some confusing information out there.

Wire colours:
Black or screen/shield is- 0v

Red is supply - c9V (from the display head) - measure it relative to the black

Green to shield is anything from c2V to c5V - this is a sine wave signal from the wind vane.

Blue to shield is anything from c2V to c5V - this is the cos-sine signal from the wind vane (confusingly these are sometimes called starboard/port, although they are not).

Yellow to shield is EITHER 0V or c5V - this is a pulse signal (2 pulses/per rotation) of the anemometer. If the anemometer is rotating then a digital meter will probably show about 2.5V; if stationery, then 0V or 5V.

A new pcbfor the mast head unit from Hudson at Hamble is about £100. Easy to fit once the mast head unit is on the kitchen table.

 

[DannyB]

I know, with the wires connected I am getting 8V between yellow and shield, does this mean the instrument is faulty, the mast head unit or both. I can't find anything to say what voltages should exist on the back of the meter. Everything points to the MHU being US but I can't see any reason why there should be 8V on the back of the meter on the yellow wire. Do I risk fitting a new MHU, and possibly blow it up ?

 

[RichardS]

My ST60+ is just showing 0.0 although if I push the true/app button it shows boat speed.

I assume that we're talking about the wind instrument so the true / app button displayes true / app wind speed. When you say that it displays boat speed presumably you mean that it displays a true wind speed but that is exactly the same as the boat speed i.e. the instrument is supposed to be offsetting boat speed against wind apparent wind speed but it isn't receiving that so it ends up thinking that the boat speed is the true wind speed.

Presumably it does exactly the same and shows the same figure whether you are heading into the wind or running downwind?

Richard

 

[DannyB]

Correct !
The mast head unit can only measure apparent wind speed, true speed must be derived from apparent speed minus boat speed from the sea talk bus. I'm only seeing boat speed shown as wind, apparent speed must be zero.

 

[Minchsailor]

I know, with the wires connected I am getting 8V between yellow and shield, does this mean the instrument is faulty, the mast head unit or both. I can't find anything to say what voltages should exist on the back of the meter. Everything points to the MHU being US but I can't see any reason why there should be 8V on the back of the meter on the yellow wire. Do I risk fitting a new MHU, and possibly blow it up ?

The yellow wire is a square wave pulse with a 50-50 mark space ratio (if it a light house, it would be isophase). Ov or 5V when the anemometer stationery, c2.5V if rotating. 8V is definitely wrong.

Disconnect the yellow wire from the display, measure the voltage on the yellow pin on the display (with respect to the black). If this is approx 0V, then the display is probably OK, if it is 8V, then I suspect the display is faulty (it may also have blown-up the mast head unit).

No need to buy a complete mast head unit for £££££s. The pcb is c£100; bit fiddly to replace, but doable.

Service manual here:

http://www.olajedatos.com/documentos/New Windvane ser man.pdf

 

[DannyB]

Quick update, I've pulled the display out and with the wiring disconnected I'm getting 8V between both red and screen, and yellow and screen. Now I also have a wind repeater on the other side of the boat, which I assumed would be just a dumb display, however, I checked and it appears to be an identical meter, only without the wiring, the only connection is the Seatalk cable. So a quick check on the connections on the back of the repeater and 8 Volts on the red and yellow. So I can't believe I have two meters with identical faults, specially when one of them wasn't even connected, the 8 Volts must be correct. So next thing is a trip to the top of the mast.

 

[saltylegs]

I haven't measured voltages yet but I have the same issue as you, ie 0 app wind speed, but if I push the button for true speed it shows boat speed.
The reason I haven't bothered checking the voltages is because I can see the the cups are not turning.
Are your cups turning? and if so are they still connected to the shaft?

 

[DannyB]

Yes, my cups are spinning normally. I have no way of telling if they are rotating the shaft, until I get up there.