Nokta FoRs Gold - Possible EMI Issue - Video

[DizzyDigger]

Took the FoRs Gold out again yesterday for some coin shooting at
our city park, and again blamed the constant chattering (EMI) on the
local power lines that were about 50 yds. away. Still, it's getting annoying.

This afternoon I drove a few miles back in the hills just to check if the
unit was chattering there too. It was, and there was not a source for EMI
within miles from the location.

Maybe I'm just nuts, and this is how the unit is supposed to sound, but
I do have my doubts. Spent many years in the world of EMC (Electro-magnetic
Compatibility) and know quite well what EMI sounds like.

Needed to have someone else with some knowledge of detectors take
a listen to it, just to make sure I'm not off-base. Made a quick video,
and while the video portion isn't great, the audio is what it's all about.

Do me a favor, if ya would, and listen to the machine. Is this typical
of a FoRs Gold?



Should add here that EMI does not always come from an external source,
although that is common. Other common sources for EMI are internal, relating
to circuit board design, or conducted, meaning the EMI follows a cable or loose
wire in the control box (acting as an antenna), and carrying the interference
into the electronics.

 

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[Treasure_Hunter]

Dizzy, have you tried manual ground balance on it? It doesn't appear you got successful ground balance in the auto mode. I have only ground balanced them in Florida on land and at the beach.

Californiagold is the member you should talk to, he has the gold and uses it often..

 

[DizzyDigger]

Dizzy, have you tried manual ground balance on it? It doesn't
appear you got successful ground balance in the auto mode. I have only ground balanced them in
Florida on land and at the beach.

Californiagold is the member you should talk to, he has the gold and uses it often..

I should have clarified that I ground balanced using the GB button
on top of the grip. Haven't used the "Auto Balance" button yet as the
manual suggested that was best for use in the GEN (all - metal) mode.

Yeah..hoping CG will see the thread and give me his opinion.

 

[QNCrazy]

Okay Dizz, I just turned mine on, factory settings, and it chattered like that indoors. Two things to try, adjust the sensitivity down or the ID mask up and see if that does anything. Shouldn't take much adjustment on either. Let me know what your results are.

 

[DizzyDigger]

Okay Dizz, I just turned mine on, factory settings, and it chattered
like that indoors. Two things to try, adjust the sensitivity down or the ID mask up and see if that
does anything. Shouldn't take much adjustment on either. Let me know what your results are.

Damn good idea!

I also want to try a fully manual ground balance, as TH suggested.

TH, you were correct in that I was using the "auto-ground balance" feature.
Went back and re-read the manual, and realized I had been using the
Auto GB feature. Still, it did GB properly as I'd get that little, high-pitched
"beep" when it was balanced. I can't actually hear that beep, but I had a
neighbor listen and he could hear it well.

Just took it out to the driveway, and did a full manual GB, which made no
difference in the chatter, unfortunately, but this does mean the machine
is GB'ing properly.

Started in BST mode, did the manual GB (no change in chatter) and
then adjusted the sensitivity down one digit at a time, and when it got
down to 38-40 the chattering was gone. Then I turned the sensitivity
back to preset (50), and began increasing the discrimination (ID Mask)
until the chattering stopped. With the ID mask at 40 the chattering
stopped.

To have to run with the sensitivity at less than 40, or the ID Mask
over 35 is just not acceptable. In ideal conditions I'd run the ID
Mask about 10, and the Sensitivity up in the 80-99 range.

I'd like to take a drive 10 miles or so back into the hills, and try it out in
some areas that could hold very small nuggets. A big rainstorm is on the
way in tonight (), so it'll have to wait a few days.

For those following the news, we're on fire up here in WA. The closest
fire to me is now at 8000 acres and they don't expect containment until
mid-October. The largest fire is the Okanogan Complex fire, and it's
burned up over 280,000 acres...so far, and it's only 17% contained.

Fire closest to me is the Upper Skagit Complex:

http://gacc.nifc.gov/nwcc/information/firemap.aspx

Those fires need all the rain they can get..

 

[QNCrazy]

The sensitivity adjustment sounds about right. But I only had to adjust the discrimination mode to 15. Outside I have no problems unless I'm near the house and even then the chatter is tolerable. In bst mode behind the house I set sensitivity at 80 and discrimination 10 with no chatter.

 

[NeoTokyo]

That is way too much chatter.

Check your connections again, make sure that there is no water or dirt in them.
Check the entire length of the cable too.

I noticed that when I screwed the nut down on the cable that I had to put a little extra force on it to get it to seat all the way to the control box.

Try switching coils too to see if the chatter goes away.
If it goes away then there is a problem with that coil or cable.

I hope that you get it sorted out and don't have to send the whole thing in.

 

[NeoTokyo]

Oh also check to make sure that you didn't pick up some mineralized soil or debris on the coil that would keep setting it off.
Stuff likes to hide right under the pole attachment and in the groove that the coil protector makes against the coil.

I set my sensitivity up to about 85 max before I start noticing chatter issues.
I believe CaliforniaGold also uses upwards of 85 for sensitivity.

 

[DizzyDigger]

Thanks for the tips Neo, but I've checked and re-checked every cable,
coil and connection a dozen times. I've gone as far as using a magnifying
glass to check the insides of the connectors just to make sure there wasn't
a fine piece of wire from the cable shielding that was shorting out a pin.

Everything put together just right. Heck, I even took off the silver-color lined
part# sticker on top of the coil to see if that made a difference. Nope..so
I put it back on.

Next step is to have Dilek from Nokta get one of her engineers to look
and the video. Could be a fix they've been working on, or an issue they
ran into during design, and he/she will spot it right off. If I do have to
ship something back, hopefully it will just be the control box, as that's
where the issue is.

 

[QNCrazy]

Neo, when you fire up your detector indoors with factory settings, do you get any chatter at all? I was thinking that if yours and Cali's don't do that, then perhaps the batch of detectors Dizz and I got, as we ordered them at the same time, could be a bad batch.

TH, it appears you have a connection with Kellyco. Can you see if they have received any calls on this matter from other individuals who purchased their detectors at the same time Dizz and I did? I know they had four or five in stock when I ordered mine and from another post they are waiting on a new shipment. So anyone who has received one in the past couple of weeks could have a detector from the same batch as Dizz and I. I received mine on August 14th.

Just thinking a little outside the box to try and figure this thing out. It's a great metal detector, no doubt, but electronics are electronics and circuit boards and processors can be manufactured with flaws.

 

[QNCrazy]

Dizz, I just thought of something else, do you think a cellphone can cause enough EMI to mess with the detector?

 

[californiagold]

Yeah dizzy try all the stuff previously mention by others here.
Does it do this while sitting still while the coil is on the ground while sitting on a quiet spot. Have u tried other coils?
If I try my fors outside of house I get emi. Moreso if I lift the coil up in the air. Definitely inside the house I get alot of emi.
But out in the woods my fors only slightly chatters on the strong mineralization when I turn up the sens. 85 or so.
My old gb pro had a similar sounding issue. It was a leaking coil. Water was faulting the coil and it chatted non stop. If all these dont fix. Would be good idea to send video to dilek@noktadetectors. Com. She can show her engineers. But your video kinda sounds like a faulting coil to me.

 

[QNCrazy]

Yeah dizzy try all the stuff previously mention by others here.
Does it do this while sitting still while the coil is on the ground while sitting on a quiet spot. Have u tried other coils?
If I try my fors outside of house I get emi. Moreso if I lift the coil up in the air. Definitely inside the house I get alot of emi.
But out in the woods my fors only slightly chatters on the strong mineralization when I turn up the sens. 85 or so.
My old gb pro had a similar sounding issue. It was a leaking coil. Water was faulting the coil and it chatted non stop. If all these dont fix. Would be good idea to send video to dilek@noktadetectors. Com. She can show her engineers. But your video kinda sounds like a faulting coil to me.

Cali, this is exactly how mine acts. Thanks for reassurannce that there is nothing wrong with my detector. Have you had any problems with the Ground Balance button?

 

[Treasure_Hunter]

Diz,

Cell phone can cause EMI, as can recording a video.... Not saying that is the issue at all but it is worth checking out. Watching the video it does not appear to be ground balanced, it seems to beep too quickly from what I have seen, I dont own one but buy have played with one several times for total of maybe 5-6 hours......As California said it could be a bad coil too....

 

[californiagold]

No problems with my gb button. Whats wrong with yours? Also as mentioned earlier the manual gb vs auto tracking has no effect on emi. Just mineralization.
Dizzy if you try you fors in boost and turn down your sens. Till it only chirps once in awhile. I think you said 38-40 sens. And leave your id mask at 10. Can you get a measurement of a modern nickel with a repeatable signal. I seen a guy in europe with a fors core that was getting same depth as others with sens. Turned up. Basically his detector was at 40 sens and was getting same as 85 sens on other fors. Some reason his sens. Reading wasnt to scale. He had it replaced.

 

[QNCrazy]

No problems with my gb button. Whats wrong with yours?

Well, the nut holding it in place has come off. It still works but it is loose. It's an easy fix by removing a few screws and putting it back on. I guess I'll call Kellyco about it. I would hate to have to send it back for something I can fix in less than 15 minutes.

 

[californiagold]

Yeah you should get that fixed. Kellyco stocks new joystick shafts. They should replace it. I dont think you should take it apart. It would probably void the warranty.

 

[QNCrazy]

Just got off the phone with Kellyco repair center. I described the problem and they told me if I felt comfortable with it to fix it myself. They also said if the problem persists they will still honor the warranty. Now that's customer service.

Sorry Dizz, didn't mean to higjack your thread.

 

[californiagold]

Thats cool. I figured they wouldnt want u to take it apart.

 

[Treasure_Hunter]

Well, the nut holding it in place has come off. It still works but it is loose. It's an easy fix by removing a few screws and putting it back on. I guess I'll call Kellyco about it. I would hate to have to send it back for something I can fix in less than 15 minutes.

They will most likely tell you if you can and do feel comfortable doing it to go ahead, your warranty will still be good if it fails and if it is the joystick they will send you a new one...