prism problems

[Rookie2]

I have had my Whites Prism iv for about 3 years now and it has worked great. Recently though it has been acting up. I can take it out in the yard and it works great for like 5 minutes and then all of a sudden it will start telling me that the coin is much deeper than it is and the pinpoint mode stops working. When I press the pinpoint button when I first start using the machine(within the first 5 min. or so) it pinpoints great and has correct depth reading. Then like I said after about 5 minutes of use it will tell me the coin that it had previously identified as being 2 inches or so deep will read 8 inches deep and the pinpoint sticks. There will be a constant low hum when pinpoint is engaged and the sound and volume is constant even when going over the target. Now when this pinpoint sticks I can run it by something very large like a playground metal pole and when I get right next to it the pinpoint will come out of the constant low hum and really sound off like it is supposed to. But then when I try to go back to detecting it starts sticking again. Anyone have any idea what the prob. might be?

[underdogger]

What I think the problem is you may have some fine dirt in between coil and coil cover . I Now own a priz IV . I have no expertise on the IV . However I own a II and I had the same problem. with the II that you are. First if you have a coil cover take it off , clean it and replace . Also make sure your Coax connection is screwed tight at the box they tend to come loose. That fine dirt can play havoc with your detector . I hope this helps you . If not give whites a call . I do not think its major but I know your frustration . ROB

[Rookie2]

Hey thanks Rob, unfortunately I do not have a coil cover on the unit and my cables are all tight. I may try giving Whites a call on this one.

[Sandman]

If you haven't called White's yet, make sure the batteries are fresh and inserted correctly. I know it sounds silly, but we tend to over look the obvious. You should really use a cover to protect the edges or at least cut a section of inner tube and stretch it around the edges of the coil to stop any wear on the edge where it is weakest. Some use Marine Epoxy on the coil.