Warranty replaced coil VIDs different? Xterra 705

[Backstrap80]

Warranty replaced coil VID's different? Xterra 705

Hello,
I recently had the eliptical 18.75kh coil replaced under warranty. As soon as I got it I started air testing and noticed an immediate difference. In a spot I hunt regularly nickels were 12, zinc 30-32, copper pennies 38, dimes 40, quarters 44-42. These numbers were consistant at sensativity 24. Now it seems everything is plus 2, nickels 14,12,16-zinc 28-34 copper pennies 36-40, dimes 40-44 quarters 44-48 this is clad. To obtain the stability I used to have I have to lower sens to 22. Also the (sweet spot) under the sticker seems a lot smaller and the coil in general seems hotter. I didn't have the jumping problem before so it helps me know pull tabs from nickels, pull tabs were 14,16,14,16 now my nickels jump the same, I can't get the coil to repeat a signal. I don't want to be a pain with minelab but I hunt everyday 6-10hrs. I'm not a professional but at the moment my situation, metal detecting is providing a little extra needed income so I need good working gear.

Should I call minelab and explain my replacement coil? I only shipped the coil last time, should I send my whole machine this time? I've never really dealt with any warranties in my life, to me, they're doing me a favor but I paid for a warranty also. Anyone else have similar problems?

My first problems were erratic EMI, like I was in a house while hunting. Lowering the sens to 14, auto noise etc nothing would help, I'd have to lightly tap the coil flat on the ground, it does its doing that again after about the first week. Now I either very very lightly tap (trying to avoid another warranty) if that doesn't work I tighten or loosen the coil (makes a huge stability difference on this new coil) and then pass the coil over my digger, the signal usually snaps it out of the chatter.
I have a couple back up machines now so I'm thinking ship the whole machine back for a check up?

 

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[Longhair]

Have you ever done a factory reset on the machine? It may help straighten out glitches that can be accumulative.
I've rarely had need to do a reset, but I know others that perform it as a matter of routine maintenance.

 

[Backstrap80]

Every time I switch coils I do a reset. It's almost like a ground balance issue. Without repeatable signals I'm digging on luck alone. Some times the chatter is so bad I have to wait it out. I started using ground tracking and it helped a little but quarters are still 46 at 24 sens. I got an RMA. Hopefully it's something simple. It used to hit nickels solid at 5-6" solid repeatable 12 now at 2" they are all over.
I'm fully explaining the symptoms incase someone else in the future gets the same problems. Thanks for your help. Is there any cleaning I should do?

 

[Longhair]

Nah. It sounds like you got a bad replacement coil. It shouldn't be that unstable or inconsistent. Nickels should be a solid 12 with both the HF and MF coils.

 

[Backstrap80]

I sent it back in and this time they replaced the board inside the display. I wrote a loong letter to accompany it like Nadia said and explained it air test fine, its when its on the rod end. I decided to do my own diagnostics today and it seems youre correct about bad replacement coil. Turning the bolt in the rod 1/16th of an inch, any pressure on the coil housing results in high quarter-46 again but now it bounces. I dug a penny today at VDI 10, i checked the hole for 5 minutes nothing there. Im so frustrated, if i couod sell it and buy a new one i would but the machine is so bad i went over a dime in 1" of bark freshly dropped. Today, Left swing was 38, right swing was 42. Im frustrated because in my letter i asked the tech to call me so i could explain further, i never got a call or any contact. I had to call kelley co to get tracking #s as it was in the mail,
Ive had it back 2 days and tried 4 fields i know well, one i can hit nickels at a solid #12 down to 6" now nickels 1" under jump from 8-20.
Enough venting... Does anyone know if i can use another coil i have without risk of damage? If its not the coil i dont want to burn other coils up ill be using on my 305 while this ones gone another month.

 

[Backstrap80]

Update for reference. I talked to a kelleyco tech, he said the machine doesnt have the power to burn a coul up so im going to swap coils out and try to isolate the problem to the coil. I did some more testing of my own and any pressure change on the rod bolt, super gentle squeeze of the coil, bolt tighter by 1/8th of an inch or looser by 1/8th results in different air test results also. Im pretty sure i had a bad PC board and got a bad replacement coil that just made things worse, its super super stable now, i didnt have to touch noise control, just VDI's are wacky, ill update when its fixed for future readers.