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Chet

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About Chet

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  1. Norvic, that’s good information and I will use your method. I will initially go to Auto Ground Balance mode to speed up the process. Then return to Semi Auto Ground Balance mode. If that fails then “Reset All” may save a walk to the truck to change coils? Have a good day, Chet
  2. I don’t have an X-Coil yet. But it appears that resetting the GPZ default settings in the Menu may provide a method to recover from an X-Coil ferrite balance problem. I tried the following experiment. Use headphones plugged directly into the back of the GPZ for this procedure. 1. While in Manual Ground Balance mode; upset the ferrite balance by holding the Quick-Trak button in for about 15-20 seconds while waving the coil over a chunk of iron. 2. Do not press the Quick-Trak button for this step. Verify that the ferrite balance is upset by waving the coil over the yellow ferrite core. Note the loudness of the ferrite response. 3. Page through the Menu to “Reset Settings”; open it and move to the right to select the Check mark; select it. This restores the factory default settings. It appears that it may to also set the ferrite balance to a reasonable default value. 4. Now wave the coil over the yellow ferrite core. The loudness of the ferrite core should be greatly diminished. 5. Restore individual favorite settings and turn on the GPS and WM-12 if you use them. I did this in my back yard with terrible EMI from the neighborhood. So even though it appeared to work it needs to be verified away from EMI. Have a good day, Chet
  3. I have the 10” and 17” X-Coils on order. My decision to purchase them is based on my thoughts/opinions of possible improved performances are as follows; The lowering the X-Coil transmit coil approximately 2cm/0.75” creates an exponentially greater target signal return to the receiver coils. DOD receiver coils are wired in series (voltage adding) so that with a large target the returned signals are combined effectively into one centered search lobe similar to a Mono coil. A very small shallow/weak target normally does not return enough signal strength to both receive coils to be formed into a Mono like search lobe. Thus they are predominantly detected in the more sensitive areas near the windings. The lowering of the X-Coil transmit coil approximately 2cm/0.75” creates exponentially greater signal strength from a small target. This can produce enough signal from some small targets into both receive coils to provide a Mono coil like search lobe. This will be most evident with smaller coils that concentrate the transmit energy into a smaller area. The exponential transmit and receive gain/sensitivity and resultant depth gain of the X-coil is similar to scraping away the surface debris to get closer to the target. At the same time receiving exponentially a louder and sharper response. The larger X-coils that have the transmit coil wound in some form of a spiral that should have some improved performance as seen in other spiral wound commercial coils. Some performance gain may have been made by changing the number of turns in the transmit coil and/or receive coil. They could be altered within reasonable design limits of the electronics. Some of the pros and cons of these coils have already been discussed. More experiences and reports from the field will be interesting. Have a good day, Chet
  4. Hi Rick In most detector coils there is a conductive coat of black paint that forms a Faraday shield between the coil and the ground to reduce electric capacitance effects. Is there some kind of shield that is not shown in this photo? I don’t see a shield in the Minelab photo either. Perhaps it is not needed in the GPZ 7000 Zero Voltage Transmission (ZVT) design? Thank you for this interesting photo and have a good day, Chet
  5. The X Signal term has been used in metal detector technology for many years. The X Signal is the magnetic effects generated by the transmitter and detected by the receiver. Another received signal used in VLF detectors is a resistive R Signal. This website will automatically download a .pdf file that may help some on this subject. https://www.iaom.info/wp-content/uploads/06mdpkgwc17.pdf The original GPZ equations may have had problems with auto ground balancing tracking because of the non-linear effects that the nanoparticles created in the magnetic X Signal returned from highly mineralized soil. Thus the Ferrite balancing routine was incorporated to provide a workaround for the problem. When detecting in Nevada after a rainstorm the GPZ gets a lot of ground noise and on buried test targets it loses depth. A combination of effects caused by the wet desert soil should be considered; soil temperature is affecting the nanoparticles; wet salt may be causing some kind of magnetic change in the soil; wet salt may be causing more conductivity loss through the soil. Have a good day, Chet
  6. My understanding of the how Ground and Ferrite balancing may work??? Soil contains minerals such as iron and other particles that create a somewhat constant Ground signal that can be averaged and fed into the GPZ 7000 mathematical equations as a Ground tracking value. Ground tracking across different up/down distances of unleveled ground is possible as long as the magnetic ground response is linear. Linear meaning that as the coil goes close to the ground and then away from the ground a uniform Ground signal strength change is expected. The GPZ equations know from constant Ground tracking and/or you pumping the coil up and down periodically what kind of linear/uniform Ground signal response it should receive from the ground at different heights. Superparamagnetic particles normally do not have magnetic hysteresis or B curve like a small particle of iron. They do not retain a magnetic charge or north/south alignment like a small iron particle will. They change characteristics as the soil changes temperature. They are easily magnetically saturated. When the soil contains great numbers of these Superparamagnetic particles and they become saturated they generate a non-linear/non-uniform Ground signal that disrupts the GPZ ground tracking and target processing equations. To mitigate this X Signal problem the Ferrite balancing routine is providing a value into the GPZ mathematic equations to handle normal soil X Signal levels. The Ferrite value may be weighted in the different ground modes Normal, Difficult and Severe. The Superparamagnetic particles nearest the overlap of the Transmit and Receiver windings near the center of the coil are the most susceptible to becoming saturated. The Transmit winding is 2 cm above the Receiver windings to increase the distance to the soil and reduce the stronger magnetic lines of force that are close to the transmit coil from saturating these particles. Why is Proper Ferrite and Ground balancing important? The transmit pulse energizes the metal target that causes magnetic currents to generate a short duration magnetic field that is sensed by the receiver coils. The detectable duration of the target return is called the Time Constant of the target. Small gold nuggets have a very short Time Constant as well a weak signal return. Larger nuggets, bullets, nails, and junk have long Time Constants. Soil has a Time Constant that is similar to small nuggets. Small nuggets that have Time Constants that are shorter or longer than soil can be detected. Small nuggets that have the same time constant as soil may not be detected. For small nugget detection it is important that accurate, narrow Ground and X Signal values be maintained. Have a good day, Chet
  7. Referencing this patent; which discusses the GPZ 7000 and possible coil options; United States Patent Application 20130154649 CANDY; Bruce Halcro June 20, 2013 TRANSMIT SIGNAL OF A METAL DETECTOR In searching using edit and find functions for the word “Saturation” and “X” it came up with references that place the Transmit coil 2cm above the receive coil to reduce saturation of the soil. This 2 cm is important in highly mineralized ground that effects the processing of the X signal response. The X signal occurs from non-linear reactions of magnetic components of saturable ground that have the property of viscous superparamagnetism. Superparamagnetism is a form of magnetism which appears in small ferromagnetic or ferrimagnetic nanoparticles. It is important for the GPZ 7000 to avoid saturation of the soil so as to reduce the X signal response to a manageable level that can be processed out and allow weak gold responses to be processed. What may be happening with the X coils on highly mineralized ground? Going by the descriptions stated in the forums; the coils are flatter than the factory coils. This implies that the 2 cm separation between the lower receive coils and the upper transmit coil is not there. This would allow the transmit coil to be closer to the soil and disturb the X signal response when over highly mineralized soil. A possible solution that should be tried in the field on hot ground is to swing the coil 2 cm/0.79 in. higher than normal. Some experimenting may be required to resolve the problem that Andy had with the 10” X coil. Perhaps ferrite balancing on quiet soil or in the air. Once it is accomplished it is stored and will return to the same setting when powered up again. Have a good day, Chet
  8. If you want to make a backup/replacement One-wire ID chip for the coil here is what you will need. The video explains the process rather well. It will require that you shave off enough plastic on the 7 pin plug to read the chip number. https://www.youtube.com/watch?v=r2T78o7oxfQ&t=9s https://www.ebay.com/itm/Serial-EEPROM-FLASH-PROGRAMMER-1-5-5V-ICSP-USB-24x-25x-93x-95x/301984133071?hash=item464fa82fcf:g:acAAAOSwjVVVp-Gd https://www.digikey.com/products/en/integrated-circuits-ics/interface-specialized/754?k=one-wire Have a good day, Chet
  9. Jason I apologize, reading back I saw that you had already addressed the bulkhead connector as a possible problem. And I agree that the software should be reloaded. Have a good day, Chet
  10. Condor What kind of error do you get; coil not connected; coil overload; or some other error? Minelab detectors are normally pretty forgiving in their coil circuity and survive most faults. So I would first suspect and look for a bad connection in the bulkhead female connector. The original large Minelab 7 pin connector threaded ring should be almost flush with the bulkhead when the plug is completely seated. The large Minelab 7 pin female bulkhead connector may have a female pin that has been damaged or broken within the plastic encasement. With a bright light and a toothpick inspect each female pin for unusual looseness or movement. Maybe a solder joint on the backside of the bulkhead connector has failed. The only way to properly check this would be to open the Bulkhead and check continuity through each of the 7 pins. Unfortunately this is not a simple check and repair for the average person in the field. And it is possible as others have stated that it will require service from a Minelab repair center. Good luck and hopefully a better day, Chet
  11. The problems were with the Minelab 14”coil. I am on the list to purchase some X-coils. I look forward to giving them a run in some heavily detected areas. Have a good day, Chet
  12. Andy Though not the same as your problem; I will share some similar severe problems that I have had with ground balancing. I normally run in High Yield; Normal with Semiautomatic ground balancing mode. My problems were self-inflected by allowing the coil to set on an iron reinforced floor while connected to my computer for transferring Find points and Way points. Another was caused by reviewing Find points and Way points while inside the car during a rainstorm. While the coil was setting on the passenger side floor pan. In both cases the detector sounded like a machine gun as it was sweep across mild ground. The ferrite core was of no use until several minutes of waving the coil over the ground wile holding the trigger in. Another similar problem occurred when trying to ground balance on the ferrite core near a solar system. The solar charge controller was generating EMI that prevented it from ground balancing. Moving away about 100 ft cured the problem. Have a good day, Chet
  13. Hi Norvic I agree with your caution of avoiding the three small pins. Minelab is most likely using a standard One-wire identification integrated circuit chip. The low voltage and low current of the multimeter even in a reversed polarity condition will normally not do harm to the chip. The real danger is on a cold day the discharge of static electric spark could damage the chip. Have a good day, Chet
  14. Hi Trent Try the following checks with a multimeter with the ohms/resistance mode set to the lowest measurement scale. With the new patch cord connected to the original 14” or 19” coil you should get the following resistances on the Minelab 7 pin male plug; The four large pins are numbered 1-4 in a clockwise direction starting to the right of the plastic guide bump. You can read them with a bright light. Measuring across the receive pins 1 and 4 should read 6 ohms +/- 2 ohms. Measuring across the transmit pins 2 and 3 should read 0.4 ohms +/- 0.2 ohms. Measuring between pins 1 and 2 or 3 and 4 should not have a reading unless there is a shorted connection. Repeating the above measurements with the X Coil connected to the patch cord should produce similar results. The measurements will vary a few ohms depending on the accuracy of the multimeter and the wire diameter and length that is used in the each transmit and receive coil. The three small pins across the middle are for the Minelab chip inside the molded plug. They are not affected by the patch cord connections that you have made. Have a good day, Chet
  15. Hi Dave Which X-Coil winding type has the best performance Spiral or Traditional wound? Are all of the X-Coils sizes available in Spiral wound? Thank you and have a good day, Chet
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