Is the X-Terra's pinpoint mode a flawed design?

[Mick in Dubbo]

I finally got to get some time to take my X-Terra outside today to run it through it's paces. I couldn't help but notice that while I go into pinpoint that a coin that is 2 inches to the left of the coil, shows up on the metre as being in the centre of the coil.
the second time that I sent my machine back for repair, a coin would only have to be either under the coil, or within a couple of inches of it, to give a reading that it was in the middle of the coil. I sent back the coil as well and it got a clean bill of health from Minelab (not that that means much due to what I've gone through with them).
Nobody has ever commented on this on the forum before, so I don't know if I've got a faulty coil that was given a clean bill of health, or whether I've got another dodgy control box, or if it is a design fault.
If anybody can throw some light on this, I would appreciate it.
Mick Evans.

 

[bfodnes]

To me its the best working pinpoint ever, some other detectors have a visual pinpoint aswell.

I have yet to find the pinpoint off at all unless a coin on edge or a rusty nail messes it up and those scenarios do that with any detector.

I use both the pinpoint and the prospect mode to pinpoint, prospect mode gives me two feedbacks simultanously. If it blanks out its some ferrous there if not it is an instant pinpoint.

If its a ferrous object there and I still want to dig it i then turn to pinpoint mode. The prospect mode with no iron mask however is capable of seeing two very close objects as a coin close to something else.

 

[wpaxt]

Mick,

Sorry to hear that you are having some pinpointing problems. Which model do you have? I have field tested all 3 X-Terra's and have found the pinpointing to be uniformly superb on all three machines regardless of the coil used. Have you done some air testing to see if the same problem occurs? Perhaps a test garden run through would help. All detectors can be off on pinpoint from time to time based upon position of the coin, soil conditions (lots of nearby trash, for example) and the like. Even my Explorer II with the DD coil, which I think is the easiest coil to pinpoint with that I have ever used, at times is off and I will find the target about 2" up & to the right of the tip of the coil. Often it is trash or a corroded zinc.

So I would suggest trying some tests & then post your results. Then we should be better able to identify the problem which may or may not be detector related.

Bill (S. CA)

 

[Bugar In. USA]

It Pinpoints right on, smack in the middle, unless there's some other trash or junk near what i'm trying to PP, try it with just a coin laying out by itself, in a clear spot- Good luck

 

[Elton]

Hi Mick:

I have never had a problem with pinpoint on either of the machines one 50 and two 70's....You might want to get that checked out.
Elton

 

[Mick in Dubbo]

My early memories of using my X-Terra 30, was that it had a very good pinpoint. The tests I did last night were in the back yard. The coin would give a centred signal, when it is one and a half or two inches to the left of the out side edge of the outer coil. It's not any where as pronounced as it is when in the middle, but still sounding off. Pinpointing will only ever tell me that the coin is under the inner coil somewhere, even when I detune it. Maybe I been spoiled by my Ace, which is almost always within half an inch of the target.
I'm not going to continue any farther tests or spend any more money on it. At the moment, I have disassembled it, and if nobody is able to throw any light on it, then I consider it a retired machine that my son can play with.
Mick Evans.

 

[bfodnes]

Well, I never tried a Terra 30 but I had a Ace 250 for my son. All I can say is that the 250 is a toy in comparizon to the Terra 70 and even the 50. Maybe we are talking two different ballgames.

Regards.

Bjorn

 

[Bugar In. USA]

30 , 50 , 70 , should all PP the very same, and the 250=>

 

[pinpointa]

Hi Mick,

I have been 30 and i have seen 50 and i am one year off 70 but you have flawed me to the point where i dubbno.:

Regards Pinpointa Down Under In Oz.

 

[Mick in Dubbo]

For that reason alone, I'll consider one more chance. When I take my red toy out to play, and who knows, if I keep it long enough, it may turn 70, turn grey and retire! Does the round DD coil (because of the X-Terra's faster recovery speed)give a better pinpoint than the same coil on the Explorer and Quattro?
Mick Evans.

 

[B.T]

Sounds like something is not right there Mick.
My 70 pinpoints spot on, dead centre. Sometimes it can get weird such as too much audio on the initial, first sweep or attempt to pinpoint but it settles after another one or two. Doing that doesnt bother me really at all as it always still ends up showing where the target is located. Sounds like a problem somewhere, pinpoint should mean just that, pinpoint. I have seen on some coils, not the Terras, yet, where there are weak spots on the coils circumfrence detection wise. One was a coiltek 18" mono where if you passed over a target , small say 2 g of gold, close to the coil and near that weak detecting wise spot you would nearly not even hear it, yet any other possie of the coil gave a good loud signal. Could that type of thing be the cause of your off centre pinpointing? Maybe get a small, very small target and check it out around the coil and see if there is a stand out spot where its really weak on the signal. Most coils do though have a weaker spot but mostly it is of little significance, the odd one though does stand out as did that 18". Others showed thay too had a slight dead zone but nothing like that one did. It may have nothing at all to do with it in the end but is something which you could have a look at.
Good luck either way Mick, nothing worse when your gears giving you the irits.

 

[John: VK2NIX]

G'day Mick! I've had the X70 for a bit over 12 months, and the pinpoint is consistently within the inner coil. No matter what metal, depth, or soil conditions. Sounds as though something could be a bit dodgy indeed.

 

[Mick in Dubbo]

I think that you might be on to something there BT. I pulled it back out of the box today and went for a hunt with it. I was still not getting an accurate pinpoint, so I pulled out the Ace again. When I sent the X-Terra back the first time, I mentioned to them that a female connector in the coil plug had been pushed in, and although I'd opened it up again, thought that it may be a problem. The technician gave it the all clear and only cleaned the circuit board. He didn't address any of the problems, so they persisted. I found out the other day when I was talking to another technician, that the first one was no longer working there. Maybe he left, maybe he got fired for poor workmanship. I'll never know.
There is often a spot to the left of the coil that picks up the target as in the centre of the coil. There maybe a an associated problem in the coil that may be relating to the pinpoint being less accurate than I remember it to be.
I'm catching up with another X-Terra owner in the next couple of days. I'll swap coils with him and see what gives.
Mick Evans.

 

[pinpointa]

Hi Mick from Dubbno,

I think thats the way to go process of elimination. If you can swap coils with some one then you can find out if it is the coil.

Hope it works out for you mick you have had a bit of a lemon their.
Regards Pinpointa Down Under In Oz.

 

[Mick in Dubbo]

Thanks Ray. I almost forgot that this fellow had an X-Terra. He uses a Quattro most of the time and has just gotten into gold hunting. I expect to find the solution tonight. If it is the coil, then I may just replace with the round DD coil. No point in just replacing it with the same coil, unless there is a cheap 2nd hand one around.
Mick Evans.

 

[Morpheus404]

My ? is when pinpointing with 18mhDD coil what is considered the center of the coil.If i am not mistaken the DD coil is described as being two D,s back to back.when ever i dig a target i am off a little.
Thanks
And keep on Swinging

 

[Digger]

You are correct that the center of a DD coil is a straight line, from front to back, right down the middle of the coil. When pinpointing with any DD coil, you are relying on your ears and eyes to tell you when you are centered over the target. That location is subject to "interpretation" with the DD coil, as the "center" runs the length of the coil. Technically, the sound might be louder as the target nears the middle portion of that line. But much of your accuracy will depend on the depth of the target, just like it does with a concentric coil.

Personally, I don't use the pinpoint mode on most of my detectors. DD coils or concentric coils. I rely on the sound to tell me when I am centered. In the case of the DD coils, I make my X across the ground, listening for the loudest sound. I "draw" an imaginary line across the ground where the center of the coil makes it's path. Then I move the coil forward and backward, perpendicular to that imaginary line. As I pull the coil back toward me, I listen for the point where the audio drops off. The target will be located directly beneath where the sound stops, at the front point of the coil. With a concentric coils, many folks think of the search pattern to be an inverted cone. But, if you analyze the electonic lines of flux, you will see that the pattern is more rounded than we typically think. I envision the pattern to be the bottom half of a sphere. Kind of like a half of a melon, with the flat side up against the bottom of the coil. And again, depending on the depth of the target, the sound may vary by an inch or two, in any direction. The shallower the target, the more discrepancy there will be in an exact pinpoint. To overcome this on small targets, some find that simply lifting the coil as you X over the target will help narrow down the location. JMHO Randy

 

[Morpheus404]

Thanks Digger Your reply was very helpful
Keep On Digging

 

[kaustin]

I agree with using sound for PP, the bulls eye is just for general ref.
The DD I have on my Elte the PP is center line front leading edge of the coil.
Just my 2 cents..
Keith

 

[Mick in Dubbo]

That's some excellent information Digger. I carried out some experiments with the information you just wrote about and got to learn from it. I only practiced on coins that I'd chucked on the ground. What I discovered though, was that with a coin on the ground, if I swept over it at a height of about 5 inches, it will only sound off in the middle of the coil. If I passed over the coin with the coil close to the ground, then I noticed that if you can pass the coil, using the part where the inner and outer coil are connected at the front half of the coil, then it seems that you can accurately identify that the coin will last sound at the junction and be directly below the outer coil at this point.
Pinpointing like this will require a fair bit of attention to be accurate, but sounds like it has some potential.
Thanks for posting about it.
Mick Evans.