F75 LTD noise

Anyone have this problem or does it sound like a problem. While hunting in the woods at old foundations when the 11" coil hits something like a twig sticking up it sounds off, does it all the time, if the undergrowth is heavy its going off all the time. any ideas or is this normal?

Check the coil connection. Also......tap the coil wire gently with the detector laying on the ground. Also.......tap the coil with your finger....lightly....and see what type of a response you acquire.

Could be a bad coil......but not the electronics. Do you have another coil......of any size?

My older F-75 has been doing that for some time now, was bothersome, but now I'm sort of use to it. The little rubber wire boot slides up the coil wire and I noticed the insulation is torn from around the coil wires. I've been holding off from sending it in because I don't have a back-up...maybe this winter. When I put on the 6x4 coil, I don't get the chirps when bumped. My buddy has a Minelab SE for a back-up and would lend it to me while my F-75 is in for repair, but you know how that is...I don't like to borrow and I'm not real fond of the MLSE, especially being so use to the speed of the F-75. But, beggars can't be choosy.

Yes I have a 5" I try that with the taps.

Ozzie. Sounds like you just need to order a new coil. Don't need to send the unit in.

Only had it since Oct shouldn't it be covered by the warranty.

Tom, Comments from another site say theres do the same thing when they bump something, the area is full of oak scrubs starter plant about 4 to 5 inches high.

Quite some time ago....... there were a bad 'batch' of coils that made it to the consumer. I thought most of them had made it back to Fisher.

In any case; yes, FTP/Fisher will replace a bad coil under warranty..........as long as the coil/coil-wire are not damaged from user/operator mishandling......and it's a Mfr defect.

Make sure it's not the connection at the housing since the connector is pretty poorly put together (soldered and shielded). The good thing is, the end screws on instead of being crimped on. You can easily (if not under warranty) remove the end and re-solder the leads - heat shrink it and put it back together. The three I've done are better than when they started.

Ok Tom I did the tap test and tapping the coil sets it off, (sounds like you are getting a hit from an object), also where the cable connect to the coil I tapped the connector and tapped the cable up to about 8" and it sounded off. Switched to the 5" coil and tapped again without getting any response.

Hi folks, just wanted to give my input on the F75 Special Edition noise. I have the same problem with my new machine, I noticed it this past weeked, so I just did a test of my own with the 11" coil and the 5" coil, this is what I found. With the 11" coil I get a lot of chatter when I gently tap the side of the coil, with the 5" coil I get some chatter when I tap the bottom of the coil. I removed the 11" coil from the rod and tapped the side of the control housing and there was no chatter. I put the control unit on the table and held the 11" coil I my hand and tapped it. I makes a lot of chatter. I hooked up the 5" coil in the same manner and tested it with the coil in my hand and it too has some chatter when I tap the bottom. So I guess I have to send the coils back to Fisher.

Shooter.........you are correct. Metalman......you may still be okay.

Shooter........you are encountering 'microphonics error'. You can send in JUST the coil........let them know I believe it's 'microphonics error'. If they do not understand this......they can ask Dave Johnson or John Gardiner.....of whom are very familiar with this issue. You can keep your F75 at home......install the other coil...........and hunt with this config (while your other coil is being warranty repaired). You may find some interesting 'tuition' with the smaller coil.

Metalman............IF your coil has bad problems with wet grass and small twiggs.......AND can not handle very light taps on the coil wire....or coil.....than you have the same problem. It is usually the coil wire that is excessively 'sensitive'......that is a dead giveaway.

Thanks Tom for the help I'm going to call Felix in the morning. Is it ok to mention you and the postings? Also I forgot to mention a few days earlier I was doing a fresh water lake beach that they lowered and the coil was in the water, after a couple of hours the unit started sounding off and the ID jumping all other the place had to stop hunting That was the only time it did that and it seems this other thing started, don't know if they are related.



Edited 1 time(s). Last edit at 12/01/2010 05:00PM by Shooter.

Thanks Tom.
I did call Felix today and left a message...havn,t heard back yet.
Would it be wise to send the whole unit in for any tune up purposes ?
Or maybe it can't be tuned up... I don't know. Other than the coil falsing, it seems to be ok.

Sure, you can mention me and/or this forum.

The T2/F75/F70 cannot be tuned up......as they are 'burned-in' microprocessors. Nothing is adjustable.