® White's Electronics, Inc. 1011 Pleasant Valley Road Sweet Home, OR 97386 USA Distribution: 1-800-547-6911 Factory: 1-541-367-6121 FAX: 1-541-367-2968 Web Site: http://www.whiteselectronics.com ©White's Electronics, Inc. P/N 621-0428 30 Printed in USA Rev.
Introduction All White's ground canceling detectors are capable of finding gold nuggets in the ground. However, none will perform as efficiently as the line of Goldmasters created especially for nugget hunting. The new GMT is the culmination of a series of Goldmasters, refined and improved over the years. With the addition of Fast Ground Tracking the GMT is the ultimate Goldmaster.
GMT Table of Contents NOTE: Due to Acrobat PDF limitations the Introductory page is on page 29 GMT Table of Contents Chapter 1 Assembly ............................................................................... 2 Assembly Instructions ......................................................................................................................... 3 Chapter 2 Batteries ................................................................................. 4 Standard Battery Holder .................
Chapter 1 GMT Assembly Assembly WASHERS BETWEEN EACH LOOP EAR & CLEVIS CABLE RETAINERS CLEVIS LOWER ROD CENTER ROD SECTION METER / DISPLAY 1/ Iron I.D. % Probability Bar Graph 2/ Type of Minerallization ( 0 to 99 ) 3/ Amount of Mineralization ( 0 to 99 ) 4/ Battery Check Bar Graph or Message 5/ Overload Message TOUCHPADS 1/ Grab 2/ Manual Gnd. Balance (-) (+) CAMLOCKS AUDIO. IRON I.D.
Chapter 1 GMT Assembly Assembly Instructions 1. Remove all parts from shipping carton and check the assembly page to make sure all parts are present. 2. Unlock "S" rod camlock and insert the reduced end of the center rod into curved "S" rod so that stainless steel spring clip buttons line up and lock into the holes in the curved "S" rod. Turn camlock to secure. 3. Fit the rubber washers between clevis/lower rod and searchcoil ears.
Chapter 2 GMT Batteries Batteries Using the Standard Battery Holder 1. Slide open the battery holder lid (decal side of battery holder) by applying gentle upward pressure on the tab of the door so that it unlocks. Slide the door away from the battery box exposing the cell positions. Ba tter CA yH UT old ION er # 802 -71 50 LIF TT AB AN DP UL 2. Remove any old cells from the holder. Note the (+) and (-) positions of each cell and the (+) and (-) for each position marked inside the cell tray.
Chapter 2 GMT Batteries Rechargeable Battery(Opt.) Battery Check A rechargeable battery system is not standard equipment with your GMT, however, high quality systems are available. White's rechargeable battery #802-5211, and charger #509-0022 are recommended and offer quick charge and overnight charge options. Rechargeable batteries deliver fairly constant voltage until they're nearly dead.
Chapter 3 GMT Quick Start GMT Quick Start 2 Iron I.D.
Chapter 3 GMT Quick Start Quick Start Instructions With the GMT properly assembled and the batteries installed, follow the instructions below to start finding those nuggets! 1 Set the Ground Balance Toggle to the Fast Autotrac position. "▼" 2 Set the Audio Signal Boost to the center (OFF) position. "▼" 3 Set the IRON I.D. toggle (under the hand grip) to the center (Audio Iron I.D. OFF) position. 4 Set the Variable SAT Speed between the 3x and 4x position.
Chapter 4 GMT Controls Controls AUDIO SIGNAL BOOST Gain Control/Power Off With the GAIN control, you increase the signal strength coming from the ground. You might expect increased signal strength to always find more nuggets at greater depths. However, high ground mineralization will "bounce" the signal back and mask good targets.
Chapter 4 GMT Controls FAST AUTOTRAC POSITION ON GROUND BALANCE TOGGLE SWITCH Gain Adjustment (cont'd) REDUCE GAIN" message is flashed, you must heed it and reduce the GAIN rather than raise it. 3. The object of increasing the GAIN is to get the maximum available depth from the detector WITHOUT causing the "BAD GROUND" message to appear, which indicates an overload of the circuit. 4.
Chapter 4 GMT Controls AUDIO SIGNAL BOOST BATTERY TEST TOGGLE Audio Signal Boost Toggle The AUDIO SIGNAL BOOST toggle switch boosts the sound (makes it louder) to help "hear" very deep or small nuggets. AUDIO SIGNAL BOOST only amplifies the sound AFTER processing thus it does not cause signal overload. AUDIO SIGNAL BOOST increases the chance of finding those tiny flakes embedded in the cracks of bedrock and the deeper, smaller targets to be found in dry washes and tailings in the desert.
Chapter 4 GMT Controls Variable SAT Speed Control The Variable SAT (Self Adjusting Threshold) Speed control knob adjusts the speed that the GMT recovers its threshold "hum" when the search-coil passes over changes in mineralization. Changes in mineralization can cause a rise or fall in the "hum". This can disrupt the smoothness of the threshold and thus obscure or hide the signal from a target. A slow, wide sweeping search coil swing gives the GMT enough ground sampling to maintain the THRESHOLD "hum".
Chapter 4 GMT Controls Iron I.D. Trigger Adjustment 1. ( Trigger Center - Iron I.D."GRUNT" OFF ) With the trigger in the center position, the GMT operates like any other Goldmaster. It responds with a "zip-zip" sound on ALL metal targets. GRAB IRON I.D. BARGRAPH (ALWAYS ON) AUDIO IRON I.D. TRIGGER SWITCH Iron I.D. Tips & Facts 1. In extreme ground conditions where Iron I.D. might not be practical, it makes more sense to dig everything.
Chapter 4 GMT Controls Threshold Control The THRESHOLD control sets the loudness of the background "hum". This background "hum" must be maintained at ALL times when searching. In order to hear the tiniest and deepest targets the THRESHOLD "hum" should be set at the faintest audible level. It can be slightly scratchy, chattery or static like but it must be constant so as to not miss that small nugget in a silent spot.
Chapter 4 GMT Controls GROUND BALANCE AMOUNT OF MINERAL REFERENCE NUMBER REFERENCE NUMBER GROUND BALANCE TOGGLE SWITCH Ground Balance Fast Auto Trac Gold is usually found in mineralized ground. To make it easier to track out the mineralized ground, the GMT has an automatic ground balance capability called FAST AUTOTRAC. Set the GROUND BALANCE toggle switch in the Initial Setting or UP position. The default GROUND BALANCE reference value of 77 (ferrite) will show in the upper LEFT portion of the display.
Chapter 4 GMT Controls Ground Balance Adjustment When you turn the GMT on, The GROUND BALANCE reference number in the upper left portion of the display shows a default value of 77(approximate level reading for a ferrite sample). After performing the "pumping" calibration described below, this reference number will be higher or lower depending on the mineralization of the ground below.
Chapter 5 GMT Searching Searching Pinpoint Technique Due to the wide scan nature of elliptical searchcoils it can be difficult to locate small targets under the physical center of the loop. Use an "X" marks the spot technique as shown in the diagram to identify the portion of ground the nugget is in. Because most nuggets are too small to isolate to an exact location as in coin or relic hunting, remove the soil under the center of the "X" until the target is no longer in the hole, but in your pile of dirt.
Chapter 5 GMT Searching Headphones The headphone jack on the GMT is located on the control box near the plug for the search coil. There is a dust cover on the headphone jack that needs to be removed before the stereo plug from the headphone is inserted. Replace it when headphones are not being used. Most prospectors prefer high quality stereo headphones so White's has chosen to wire the headphone jack for stereo.
Chapter 5 GMT Searching Chapter 4 GMT Searching Field Use & Tuning Tips Putting it all together: Once you have achieved the initial ground balance, you are ready to start searching. Move the coil just over the ground and listen for the distinct zip-zip sound produced by a target. It is wise to plant a nugget just under the soil to practice on in order to learn to recognize what it will sound like. If you don't have a nugget, use a nickel or piece of lead (sinker or bullet).
Chapter 5 GMT Searching the detector is ground balanced, the (-) & (+) controls are used only occasionally to update the ground balance setting. Old workings and outcroppings, however, can produce large ground mineral variations that make detecting such areas a little more challenging. Fast changing ground mineralization and areas loaded with hot rocks are better searched using the Fast Auto Trac Mode of the GMT. Life will be easier and simpler.
Chapter 5 GMT Searching Field Use & Tuning Tips almost impossible to eliminate all of them with one setting. Some will be identified by the I.D. system as if they were iron. In every instance, practice makes perfect. As mentioned earlier, Target Analysis mode ( Trigger Squeezed ) can usuallly make negative hot rocks disappear. It uses a new method that hasn't been available before. It is easy to use and very dependable. Try it, you will like it and learn to trust it.
Chapter 5 GMT Searching Pinpointing or "X" ing the target: In most cases, pinpointing is easily performed by merely "X-ing" or crisscrossing. The loudest part of the target will be under the center of the coil, just as with any detector. After the approximate location of the target is determined, take a handful of soil and check the hole again. Continue this process until the target is no longer in the hole, but in the hand. Try putting the handful of soil in a plastic container (pan, tray, cup, or scoop).
Chapter 5 GMT Searching Field Use & Tuning Tips mineralizatiion. High Gain and slower SAT will not get you the Gold in heavy mineralization as well as lower GAIN and a bit of faster SAT. Overload: The GMT can most always tell the difference between overload from a large metal target and extreme mineralization or hot rock. Under some unusual situations, it can seem confused and give a mixed opinion. Whichever the case, raising the search coil is the first solution.
Chapter 5 GMT Searching coil till the message and "squawk" stop, you can decide how large the target is and whether you wish to dig it up to investigate. If you get the message that the overload is from "Bad Ground", again the audio and visual indication will be only momentary, while your search coil is over the area which is overloading the unit. If the indication is only brief, you should probably just continue on searching.
Chapter 6 GMT Information Information Proper care I. Cleaning III. Storage A. Both the coiland rod are waterproof and can A. When the instrument is not in use, make sure be cleaned with fresh water and mild soap. The it is turned OFF. control box is not water proof and must be kept B. If you plan on storing your detector for long, dry. Never lift a wet coil above the height of remove the battery holder from the instrument the control box as water can run down the and remove the batteries from the holder.
Chapter 6 GMT Information Service White’s reputation has been built on quality products backed by quality service. Our Factory Authorized Service Centers are factory trained and equipped. They offer the same quality service as the factory. Service before and after the sale is the cornerstone of our customer relations.
Chapter 6 GMT Information Warranty If within two years (24 months) from the original date of purchase, your White's detector fails due to defects in either material or workmanship, White's will repair or replace at its option, all necessary parts without charge for parts or labor. Simply return the complete detector to the Dealer where you purchased it, or to your nearest Authorized Service Center. The unit must be accompanied by a detailed explanation of the symptoms of the failure.
Chapter 6 GMT Information Warranty Transfer If for any reason you should sell your GMT prior to the date the warranty expires, the remaining warranty is transferable. This transfer is authorized by calling 1-800-5476911, and getting an Authorization Number. Simply fill out the following information, including the Authorization Number, seal it in a stamped envelope, and send it to White's Electronics, 1011 Pleasant Valley Road, Sweet Home, Oregon 97386.
Chapter 6 GMT Information Video A Video cassette detailing the proper use of the Goldmaster GMT will be available soon. This video explains how to use the GMT in the field, as well as explaining the many varied options. Intended for English speaking persons, it is recorded on VHS format. White's recommends the this video cassette as a valuable learning aid for both beginners, and experienced metal detector users. For more information, please contact your Dealer.
