Took the MXT out today for a park. The quarters were coming in a VDI reading of 26 pennies at 16 Calibration Was Way off. Had to turn the discrimination down to zero to even pick up any gold readings at all. Is this a potentiometer pot problem ? I may just need to send it into whites but I'm not sure. Need advise. I am using the detector in going and jewelry mode with ground balance.
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Mxt 300 out of calibration !
- Thread starter EasySwing
- Start date
Martin,
I noted when you registered you posted that you owned a few detectors, one being the MXT 300 and that you also had the 6X10 DD coils and 5.3 (6½") Concentric coil. I would think that you probably still have at least two search coils for your MXT.
However, since the coin readings were off, then even if the issue is a bad search coil that could require a setting adjustment for some targets.
Monte
I noted when you registered you posted that you owned a few detectors, one being the MXT 300 and that you also had the 6X10 DD coils and 5.3 (6½") Concentric coil. I would think that you probably still have at least two search coils for your MXT.
So, you took the MXT out to a park and report that Quarters had a VDI of 26 and Pennies were 16. Was that from coins found in-the-ground or in a trashy area, or were those 'air tests' of coins you used to check the performance? Which search coil were you using?EasySwing said:
You only presume it is a 'calibration' error. Did you change search coils and test the target read-outs? I have owned a few detectors through the years that produced a low VDI reading for known sample targets, and in almost every case, the cause was a search coils that was "out-of-spec" ... [size=small]( aka: defective such as in internal short of it had been damaged and needs to be repaired or replaced.)[/size]EasySwing said:
What kind of gold were you using to check the detector, and again I will presume this was an 'air test.' Was it a thin gold earring, a small child's gold ring, a larger man's gold ring or maybe some sort of gold chain? Depending upon the size, shape and alloy content of the "gold" item, as well as its orientation to the search coil, you might have to reduce the Discriminate setting to the minimum or very close.EasySwing said:
However, since the coin readings were off, then even if the issue is a bad search coil that could require a setting adjustment for some targets.
It usually wouldn't be a switch problem that would cause the VDI read-out to be off. That's a different function. The first thing to do would be to check it out with one or more other search coils. If all work okay but one, send the bad coil to White's. If the MXT misbehaves regardless of the search coil used, you might want to send the detector and all coils to White's so they can fix the problem and check the coils at the same time to make sure they are all 'in-spec' and working properly.EasySwing said:
I take that to be the Coin & Jewelry mode, and do you mean you have it Ground Balanced and 'locked' or are you letting it function in the Auto-Trac® function? If you are using different specimens to do an 'air test' I would suggest getting a Ground balance and then 'Locking' the GB setting while you use sample targets.EasySwing said:
Monte
Larry (IL)
Well-known member
A really bad ground balance (locked) can screw up your VDI readings. Did you try another location?
I'm using MXT with the 6 x 9 coil on it I'm on vacation so I cannot check it with another coil but will do so when I get home. I ground balance it using coin and jewelry
remote and
I keep it in track mode been using this detector for four years now with absolutely no problems. I could Ground balance on a number of occasions in different areas and the same result occurs. I put down as a test a quarter and a nickel readings they are way off on their balancing so I have to crank down the sensitivity so that I do get some readings in the gold range. I'm not specifically looking for a piece of gold i.e. gold ring or earrings but I'll need to have access to the gold range as you know it is the pulltab Nickle through gold range. I know that iir is
not a ground balancing issue because I ground balance on a number of occasions .
I disconnected the connector for the coil and reconnected and when I turn it on and tested or with a quarter it read 26 penny 16 with no negative readings for iron objects. Discriminate knob is on "0" to pick up my wedding band. Could it be a bad potentiometer?
remote and
I keep it in track mode been using this detector for four years now with absolutely no problems. I could Ground balance on a number of occasions in different areas and the same result occurs. I put down as a test a quarter and a nickel readings they are way off on their balancing so I have to crank down the sensitivity so that I do get some readings in the gold range. I'm not specifically looking for a piece of gold i.e. gold ring or earrings but I'll need to have access to the gold range as you know it is the pulltab Nickle through gold range. I know that iir is
not a ground balancing issue because I ground balance on a number of occasions .
I disconnected the connector for the coil and reconnected and when I turn it on and tested or with a quarter it read 26 penny 16 with no negative readings for iron objects. Discriminate knob is on "0" to pick up my wedding band. Could it be a bad potentiometer?
TerrificPacific
New member
Are your batteries low? When the batteries on my MXT Pro get low, I get some weird readings.
None of the EXTERNAL potentiometers affect the VDIs. Each of the Gain, Dual CTRL and Threshold use a POT but those won't produce inaccurate VDIs. Unless you are referring to an internal POT, there are at least two internal POTS labeled 'PHASE' and 'THRESHOLD'. Of those two, the 'Phase' is the only one that could affect the VDI. I'm not sure there is a way to diagnose it but maybe if you use PROSPECTING mode and ground balance, it will display the phase on the LCD screen. I don't know that it will tell you anything but it should be within a logical range. It would be easier if you either knew what the ground phase SHOULD be or if you had another MXT to compare the ground phase with it. This image shows the MXT Pro but the circuitry should be similar.
It's possible you do have an MXT that needs attention, but I suggest you check it with another search coil first as that can often be the issue.EasySwing said:
A hunting buddy of mine just got a brand new M6. Mounted the stock 950 coil and it would hardly respond to a quarter close to the coil and the VDI response was crap! Swapped that new stock 950 for his 5.3 Eclipse coil, and the M6 worked perfectly. He has other 5.3 Eclipse and 9" spider coils and all is well. Just a defective coil and that can sometimes happen. He contacted White's to take care of the warranty registration and sent the coil off to have it replaced.
Check the coil then go from there. If it should be the MXT, White's in Sweet Home, Oregon will mend it quickly.
Monte
OregonGregg
Well-known member
Hi Marty,
As Monte said, try a different coil first before anything else. 9 times outta 10 its a bad coil. As Monte stated I just received a New M6 and it arrived with a bad stock coil. When I tried it a quarter showed up as -6 on the VDI , Iron. Tried a different coil and machine worked perfect. Sometimes these things happen and beings a Whites product, they take care of you fast.
As Monte said, try a different coil first before anything else. 9 times outta 10 its a bad coil. As Monte stated I just received a New M6 and it arrived with a bad stock coil. When I tried it a quarter showed up as -6 on the VDI , Iron. Tried a different coil and machine worked perfect. Sometimes these things happen and beings a Whites product, they take care of you fast.
vito
Well-known member
G'day,
Marty, did you confirm this by air-testing?
Very easy to do.
Lay the detector on a non metallic table, the coil a foot away from the border pointing into the air. Hopefully not that much EMI there. If you own a mobile and/or WLAN, switch it off.
If the detector is on switch it OFF. Set Trac to LOCK and mode to COIN&JEWELRY. All pots counter-clockwise.
Now switch ON the MXT and set gain to 9 (preset). DISC - 0 and lowest thresholt.
If you're now waving a quarter or a dime in 1 to 2 inch distance froom the coil the reading should be correct.
If not try changing the coil as the other gentlemen adviced and repeat the procedure.
If all this brings not the correct read out, give sweet home a call.
Anyway, HAPPY HOLIDAYS
-vito
Marty, did you confirm this by air-testing?
Very easy to do.
Lay the detector on a non metallic table, the coil a foot away from the border pointing into the air. Hopefully not that much EMI there. If you own a mobile and/or WLAN, switch it off.
If the detector is on switch it OFF. Set Trac to LOCK and mode to COIN&JEWELRY. All pots counter-clockwise.
Now switch ON the MXT and set gain to 9 (preset). DISC - 0 and lowest thresholt.
If you're now waving a quarter or a dime in 1 to 2 inch distance froom the coil the reading should be correct.
If not try changing the coil as the other gentlemen adviced and repeat the procedure.
If all this brings not the correct read out, give sweet home a call.
Anyway, HAPPY HOLIDAYS
-vito