Garrett coils

[Kiwi]

Can someone please tell me how I can test a Garrett Beach Hunter AT3 coil, I have checked it with a multimeter and only have continuity on 2 of the four terminals, should I have continuity on the other 2.
My problem is that the detector powers up ok and I get the threshold hum but get no change of noise when the coil is passed over a target (have tried several types of targets such as rings, coils etc)
All help & suggestions gratefully received as I have just purchased this waterproof unit to get out in the shallow water instead of using my Minelab X-terra 50 and worry about in getting wet

 

[Blazer-12]

I would suggest first reading the operators manual

http://www.garrett.com/hobbysite/hbby-manuals/AT3-AT4-Beach-Hunter.pdf

Than make sure you have fresh batteries in the unit. If this does not help than the only thing left is damage to the coil from water. Look at the cable very carefully to see if there are any holes on the sheathing covering the wire. Other than through a crack in the coil case water could have leaked in through a small hole in the plastic sheathing damaging the coil.

How does this happen? A difference in the air temperature between the coil and the water. When a warm coil is plunged into cold water there is a temperature change causing an air vacuum inside the coil. If there is a hole in the cable sheathing the water will be drawn into the coil through this hole.

Good Luck