Repairing Simrad IS15 Masthead Transducer with sticking bearings

[Island Time 1,246]

You can't get these any more, (or if you can, they are VERY expensive, and not worth it. If you have one, and the anemometer cups don't turn, here is what you can do.

 

Take it off the mast.

Remove the cups - a 1.5mm allen key fits the grub screw in the side of the cup center piece.

You will then see the shaft the cups mount on. There is a small 'C' clip visible on the shaft, with the lower bearing behind it.

 

Now, it is normally crap in the lower bearing that binds the system up, so you can try some crc. Then put a drill on the shaft and spin it for a bit in both directions, If the case gets hot, give it a rest, try more CRC and then, when cool, have another go.

 

This method will only help the lower bearing, there are two on the lower shaft. The shaft should turn freely in both directions with no binding and no rough spots. If it does, put it back up. If it does not, then its probably the top bearing binding as well.

 

If you need to get at the top bearing, you can pull out the shaft and bearings WITHOUT removing the 'C' clips. Just put the shaft in a vice and use a bolt to carefully tap (gently with a hammer) the alloy case away from the shaft. Once out, it's easy to remove the bearings from the shaft and replace them if required. The C clips are fragile, be careful. 

 

Once clean and turning freely, re-assemble - but when you press the shaft back into the case, use a small socket so that the load is on the bearing outer, NOT on the little C clip on the inner end of the shaft.

 

This will fix most issues with this unit, in about 30mins, with no capital outlay. The alternative is to replace ALL your instruments, or spend almost as much on cables, an AT10, and a IS20 masthead transponder!

 

Hope this is helpful to someone, sometime, even if not now!