Raymarine masthead wind instrument testing. Any thoughts?

[RichardS]

I posted a thread a week or so ago about not being able to get the correct flash/bleep response from my ST60+ wind instrument.

The Raymarine instruction was that you had to perform a factory reset on the ST60 before doing the re-aligning/re-calibrating circles, although this is not mentioned in the ST60+ manual.

Anyway, I did the full reset and the instrument still won't do the flash/bleep so I started dismanting the boat innards and testing the connections from the mast head unit at the junction box and at the ST60 display.

I have the newer type MHU with the round cups.

Anyway, Red to Shield shows exactly 8V so that's fine.

Yellow to Shield shows around 3.8V average but fluctuating as the cups spin so that's fine.

Blue to Shield (Port/Sine) shows 3.2V which should also be fine.

Green to Shield (Starboard/Cosine) shows 6.0V which should also be fine.

However, I don't think the last 2 reading are fine at all. Firstly, I'm at anchor and pointing almost directly into the wind so I would have expected the two voltage readings to be similar but one is close to the minimum and the other close to the maximum.

Secondly, as the boat swings at anchor from around 20 degrees off the wind on both sides, these voltages stay absolutely the same.

Thirdly, if I start an engine and force the boat around so that the wind is directly on the beam, the voltages maybe change by 0.1 or 0.2 of a volt. This does not seem nearly enough to me.

The Raymarine website gives the voltage range for each side but does not seem to say anything about how much this should vary up and down as the boat swings. However, my readings just don't feel variable enough and I think my MHU is shot electronically even though it's pointing as it should.

Has anyone else conducted this voltage test and arrived at any conclusions about how variable these values should be?

Many thanks

Richard

 

[pvb]

Secondly, as the boat swings at anchor from around 20 degrees off the wind on both sides, these voltages stay absolutely the same.

..... I think my MHU is shot electronically even though it's pointing as it should.

I reckon you're probably right, the blue/green voltages should vary smoothly and linearly as the heading changes.

 

[john0740]

Hi Richard
Here is a graph I made when fault-finding a ST60+ wind system a few years ago.

I expect that the "kink" in the curves is measurement error in direction setting, but hopefully this gives you some idea of the voltage level changes.
Cheers
John

 

[emandvee44]

With the new type mhu you do not get bleeps. Having replaced my mhu I went through the set up procedure rotation several times before I got the display to flash. I think the rotation time is critical as the one time we did succeed in getting the flashes did not seem much different from the previous attempts. The instructions only say turn the vessel slowly.
M

 

[Mistroma]

I went through this a few years ago when my anemometer readings were giving problems. I kept thinking I'd solved the problem at every connection from instrument to base of mast but it kept returning. I finally found the problem at the masthead connector. A quick clean with contact cleaner and smear of Contra-lube 770 solved the problem. The contacts were green but cleaned nicely and remain OK 5 years later.

Test I carried out from deck level always seemed to indicate masthead sensor was OK but unit gave problems in use.
Might be worth checking the masthead connection.

I have a copy of "Testing a ST50-ST60 Masthead Transducer" and "ST 60 Analog Instruments Service Manual" if they would be of use. I don't know if they apply to ST60+ but think test for masthead sensor is likely to be the same. It sounds as if you are already carrying out the same tests I did so documents may not be of use. My unit always tested OK but failed to read properly later. I suspected that the voltage, current, pulses reaching the instruments were just too weak by time they'd reached the display, even though OK at base of mast.

 

[matthewriches]

Had 2 of these just after winter that turned out to be bad sealing at the top plug/connector bracket thinggy.... water seeping in down the cable. Although you have readings. Are you able to swap bits about from mates or a yard boat? Would be good to try another masthead transducer if the cabling looks and tests ok.

 

[Kerenza]

With the new type mhu you do not get bleeps. Having replaced my mhu I went through the set up procedure rotation several times before I got the display to flash. I think the rotation time is critical as the one time we did succeed in getting the flashes did not seem much different from the previous attempts. The instructions only say turn the vessel slowly.
M

thanks,
at last a reply to the original query. I will persevere with my rotations.
can you remember if they were clockwise?
k

 

[pvb]

can you remember if they were clockwise?

It doesn't matter which way you turn.

 

[emandvee44]

Yes clockwise and i think i took about 1 minute for the turn. I found it easier to have a friend operate the buttons and i turned the boat.
Another point. If you have mounted the new mhu on the old block you need to remove the o ring. Also the new unit needs a different calibration factor. It is all in the instructions supplied with the unit plus the technical manual you will already have for ST60 wind -Section 4.3.
N.B. i have just read my step by step file (thoroughly�&#56835 i prepared for the operation . It is 2 complete circles and i recall the display flashed soon after the second rotation.
M

 

[Kerenza]

Operate the buttons? We're you in a calibration mode?
One of our questions was re the instructions indicating it was done post the calibration phase, ie at any time when moving.
By the way, I have replaced the pcb on my mhu and the output measurements on the bench, while within the service instructions spec, are marginally different, which is why I wish to calibrate.
The previous one was marginally outside spec on starboard.
K