It's fixed at last ! I replaced the wind vane
transducer circuit board and reinstalled it at the mast top (after a successful bench top test) and I now have wind sped and direction displaying on both my master and slave ST60+ wind instruments. Hooray !
part number is A28164 and it cost me AU$110 locally, or about US$100.
Thanks to all for your advice and support. As promised, below I have posted 11 photos to show how to replace the circuit board. It is easy - no special skills required.
In the order of the photos :
1. Wind vane removed from mast.
2. Remove this small Philips head screw from anemometer and then pull the anemometer off the spindle shaft.
3. Remove this small Philips screw from wind vane and then pull the wind vane off the spindle shaft.
4. Exploded view. left to right : screw; anemometer; transducer pod; wind vane; screw
5. The two halves of the transducer pod can be separated by unscrewing by hand (normal counter clockwise thread). But if its a bit too tough on the hands, you can insert the two tips of a pair of needle-nose pliers into any two of the four indentations in the top pod to give "extra grip" on this pod half (four indentations visible in next photo).
6. With the two pod halves separated the circuit board is revealed. You can't see it in the photo, but there is a rubber o-ring on the thread to assist with weather
proofing. Its unlikely that you need to replace it, but give it a clean and apply a little petroleum jelly or similar lubricant.
7. The circuit board is only snapped into the bottom pod half. Insert a fine tipped screw driver or something pointy into one of the two large holes in the circuit board to "flip" it out gently. Gently pull off the white cable connector noting its orientation beforehand so that you don't try to force it on incorrectly onto the new board.
8. The removed (faulty) circuit board. Note the numbers - this seems to be revision "D" of the board.
9. The new replacement circuit board - top side.
10. The new replacement circuit board - underside. Note the numbers - this seems to be revision "G" of the board.
11. The new board shown in the bottom pod half after having reconnected the cable. Make sure that the circuit board is snapped firmly into position around its full perimeter - see the small locating lugs etc., around the edge to ensure that its orientation is correct and that it is held firmly in position.
After this, screw the pod halves back together firmly and reinstall the wind vane and anemometer with the two Philips head screws. Note that the upper and lower spindle shafts have a flat face on one side to locate the anemometer and wind vane. Look carefully at these - don't force the anemometer or wind vane on, and don't over tighten the two Philips head screws. Make sure both the wind vane and anemometer spin freely and silently (not scraping on anything).
If you are confident in your handiwork then reinstall the transducer on your mast. Otherwise you can bench test your work with the aid of the schematics attached above, a 6 volt and 1.5 volt torch battery
wired in series to give roughly 7.5 volts, some fine wire and a multi-meter. Make sure you apply the power to the correct pins else you will damage the new board.