Minelab GP 3000 Metal Detector

An Important Message from Minelab

Minelab emphasizes the importance of responsible detector operation and environmental care. Users are urged to backfill all holes dug and to maintain the pristine condition of natural areas. Minelab thanks all prospectors for their efforts in protecting the environment.

The Minelab GP 3000 metal detector is shown with its various components highlighted in a circular diagram.

Detector Care and Safety

The GP 3000 is a high-quality electronic instrument designed for professional gold prospecting. To ensure its longevity:

• Keep the detector clean and dry, especially electrical connectors.
• The control box is water-resistant but not waterproof; avoid getting it wet.
• The coil is water-resistant and can be used in rain or wet conditions, but is not waterproof. Do not immerse the coil in water.
• Regularly replace items like teardrop washers and skid plates.
• Avoid exposing the detector to high temperatures or direct sunlight.
• The coil housing can wear through; use a replaceable skid plate for protection.
• Prevent dirt from entering between the coil and skid plate using silk tape. Other tapes may reduce sensitivity.
• Keep the control box and coil away from petrol and oil-based liquids. Wash any parts in contact with corrosive substances (like salt water) with fresh water.
• Clean the detector with a damp cloth and mild soap; avoid solvents.

Assembly

This section provides instructions for assembling and adjusting the GP 3000.

Unpacking Your GP 3000

The contents of the GP 3000 package are illustrated, showing components labeled A through L, including the coil, shafts, control box, and battery.

Complete Assembly Instructions

You will need to assemble the GP 3000 from its various components. Detailed assembly instructions are provided:

Assembling and Fitting the Armrest

Align the armrest halves on the upper shaft, insert nylon bolts, and secure with wing nuts. Attach the control box and then the armrest straps and cover.

Attaching the Handle and Bungy Cord

Slide the handle onto the upper shaft and tighten screws. Attach the bungy cord knuckle to the upper shaft.

Assembling the Intermediate and Upper Shaft Sections

Slide the intermediate shaft into the upper shaft. Ensure the coil has a skid plate and that teardrop washers are installed on the lower fibreglass shaft pivot end. Push the lower fibreglass shaft into the coil mounting brackets.

Attaching the Coil

Align the coil holes with the fibreglass shaft pivot end. Insert the nylon bolt and tighten the wing nut by hand, being careful not to overtighten.

Attaching the Lower Fibreglass Shaft

Slide the lower fibreglass shaft into the intermediate shaft. Adjust shaft length and coil angle for comfort, recommending a sweep length of approximately 2 meters. Secure the shaft using the spring clip and locking nut.

Securing and Connecting the Coil Cable

Ensure the control box is off. Wind the coil cable around the shaft, leaving slack near the coil. Plug the coil connector into the control box socket. Fasten the cable with provided Velcro straps.

Fitting and Connecting the Battery Pack

Fit the battery into the backpack pouch. Connect headphones and power cable to the battery cap. Put on the backpack.

Salty Environments

For salty environments, change the Soil switch to the 'Salt' setting. This requires using specially designed GP 3000 coils.

Battery and Charging

The Battery

The 6v DC rechargeable battery provides approximately 14-15 hours of operation when fully charged. It can be recharged at any time. It is crucial to fully charge the battery before storage and not leave it discharged for more than one day. Caution: Never use a 12v DC battery, as this will damage the detector and void the warranty.

Low Battery Indication

A series of signal pulses at 0.5-second intervals indicates a low battery level.

Charging the Battery

Important: Keep the battery upright when charging. Caution: Do not leave the mains charger connected for extended periods to prevent reduced battery life.

Turn the detector off before disconnecting the battery. Connect the battery cable to the appropriate charger (Mains or 12v Vehicle Charger).

Battery Chargers

Two types of chargers are supplied: Mains and 12v Vehicle Charger.

• Mains Battery Charger: Charges from local AC power outlets. Check charger rating (500mA or 1000mA). A 500mA charger takes approx. 20 hours for a full charge, while a 1000mA charger takes approx. 10 hours. Partial charges require less time.
• Vehicle Battery Charger: Charges from a vehicle's cigarette lighter socket (12v DC). The charger converts voltage for the detector battery. A red LED indicates charging status. The charger stops if vehicle battery voltage drops below 11v. Ensure your vehicle battery is in good condition and run the engine periodically to maintain charge.

Controls

Familiarizing yourself with the GP 3000 control panel is essential for effective detecting.

Detector Sounds (Easy Reference)

• Threshold and Tone: The background sound set by the Threshold and Tone controls.
• Target Signal: An abrupt change in threshold tone and volume when a target is detected. Maximum level is set by Volume; tone variation by Signal. A falling-then-rising tone may indicate a small target; a rising-then-falling tone may indicate a large target.
• Ground Noise: Irregular noises caused by ground mineralisation, reduced by the Tracking mode.
• Tune Indication: An initial beep followed by a period of quiet or chattering, concluding with three sharp beeps upon successful frequency selection.
• Low Battery Indication: Signal pulses indicating low battery power.

Control Functions: Rear Panel

The rear panel features controls for Tune, Iron Discriminate, Soil, Coil, Balance, and Coil Connector.

• Tune: Reduces electromagnetic interference. Automatic tuning takes approximately 60 seconds.
• Iron Discriminate: Selects between 'All Metal' (no discrimination) and 'Disc' (silences ferrous targets).
• Soil: Optimizes detector for different soil conditions (Normal, Sensitive, Salt).
• Coil: Changes coil sensitivity and search pattern (Double D, M/Mono, Cancel) for different environments.
• Balance: Selects between 'Fixed' ground balance or 'Tracking' (automatic).

Control Functions: Front Panel

The front panel includes controls for Power (On/Off), Boost, Threshold, Volume, Signal, and Tone.

Power (On/Off)

Turns the detector on and off. Always switch off before connecting/disconnecting coils or batteries.

Boost (Shallow/N/Deep)

Enhances target signals. 'Shallow' amplifies signals from small, near-surface targets (best for quiet ground). 'N' (Normal) is for general use. 'Deep' smooths signals in noisy ground for large, deep targets, potentially masking small near-surface targets.

Threshold

Adjusts the background audio signal. Set just above the point where it is audible and stable, ideally a smooth hum. Small or deep targets may cause only slight variations in the threshold.

Volume

Sets the maximum loudness of target signals. Maximum volume provides proportional signals. Lowering volume limits signals from larger targets or can mask most targets.

Signal

Adjusts the pitch response of target signals, affecting tone variance. High variance offers more signal definition but can cause confusion in mineralized ground.

Tone

Adjusts the tone of the threshold for comfortable hearing. Higher pitches may be fatiguing but better for faint signals.

Iron Discrimination

Silences or 'blanks' the threshold when a ferrous target is detected. In 'All Metal' mode, all targets produce varying signals without type indication. In 'Disc' mode, strong ferrous responses are silenced. Weak responses may still be heard. Pinpointing is best done in 'All Metal' mode.

Level Adjust

Selects sensitivity and likelihood of discriminating ferrous targets. It also affects ground balancing by influencing the detector's perception of ground noise versus weak targets.

Soil (Normal/Sensitive/Salt)

Optimizes detection for soil conditions. 'Normal' is versatile for most areas. 'Sensitive' is for small nuggets in highly mineralized soil but may not work well in salty ground and can reduce depth for large nuggets. 'Salt' is for high salt content areas.

Coil (Double D/M/Cancel)

Changes coil sensitivity and search pattern. 'Double D' is versatile for mineralized ground and good for pinpointing. 'M' (Mono) is for low-medium mineralisation and small nuggets, but pinpointing is off-center. 'Cancel' is for high electrical interference.

Balance (Fixed/Tracking)

Selects between 'Fixed' ground balance (remains at current level) or 'Tracking' (automatic adjustment for ground mineralisation). Change to 'Fixed' when pinpointing a target.

Tune

Reduces electromagnetic interference. Automatic tuning takes about 60 seconds, indicated by three beeps.

Operation

This chapter guides users on how to utilize the GP 3000 to its full capacity.

Quick Start Instructions

1. Set Coil switch to Double D.
2. Set Soil switch to N (Normal).
3. Set Balance switch to Fixed.
4. Set Iron Discriminate switch to All Metals.
5. Set Boost to N (Normal).
6. Set Volume to maximum, Signal to 2 o'clock.
7. Turn Power switch on.
8. Adjust Threshold for a faint audible sound.
9. Adjust Threshold Tone to suit hearing.
10. Tune the detector: hold coil vertical at waist height, move through a half-circle until interference is loudest, then press Tune switch. Tuning takes ~60 seconds.
11. For Discrimination: set Iron Discriminate to Disc, Level Adjust to middle.
12. Ground Balance: move coil up/down, change Balance to Tracking.
13. Switch Balance back to Fixed after ground balance is achieved.
14. The detector is now ready.

Detailed Operating Instructions

Turn the GP 3000 On: Hold coil away from ground/objects, switch Power to On. Important information (tuning, ground balance) is saved when turned off.

Set the Volume Control: Adjust so target signals are clear but loud signals are not uncomfortable. Test with a large and then a small target.

Set the Threshold Control: Adjust for a faint, audible threshold. Correct setting is crucial for hearing small variations from targets.

Ground Balancing

Ground mineralisation (chemicals, minerals, salts) can cause 'ground noise'. The GP 3000 has automatic ground balancing to minimize this noise and maximize sensitivity to metal targets.

• Automatic Ground Balancing: When Balance is set to Tracking, the detector continuously adjusts to ground mineralisation. Tuning takes 5 seconds initially, then continues at a reduced speed.
• Fixed vs. Tracking: Use 'Tracking' for high ground noise. Use 'Fixed' for mild ground or when pinpointing. Ground balancing may need repeating if conditions change rapidly.
• Procedure: Move coil 20-100mm above ground, change Balance from Fixed to Tracking while moving the coil. Continue until ground noise stops. A persistent signal may indicate a target. If the threshold remains stable when raising/lowering the coil, it is ground balanced. Select Fixed or Tracking for detecting.

Iron Discrimination

Discrimination helps distinguish metal types, rejecting iron rubbish. The GP 3000 can reject many iron objects while still detecting non-ferrous metals, particularly useful in littered goldfields.

• All Metal Mode: No discrimination; signals vary but don't indicate metal type.
• Disc Mode: Silences ferrous targets. Strong responses are needed for discrimination; weak responses may revert to 'all metal' mode. Pinpointing is best in 'All Metal'.

Level Adjust

Affects sensitivity and discrimination likelihood, and ground balancing perception. It helps select discrimination between ferrous and non-ferrous targets.

Soil Switch

Optimizes detection for soil conditions. 'Normal' is versatile. 'Sensitive' is for small nuggets in mineralized soil. 'Salt' is for high salt content areas.

Coil Switch

Changes coil sensitivity and pattern. 'Double D' is versatile and good for pinpointing. 'M' (Mono) is for low-medium mineralisation and small nuggets. 'Cancel' is for high electrical interference.

Balance Switch

Selects Fixed or Tracking ground balance.

Tune Control

Reduces electromagnetic interference. Automatic tuning takes ~60 seconds.

Detecting Techniques

Prospecting Techniques

The GP 3000 excels in mineralized/salty ground. Dig all target signals, even in previously detected areas. Be aware of mineral variations causing signals. Sweep coil 1-2 cm above ground in heavily mineralized areas for stability. Charcoal can mimic target signals but vanishes when disturbed.

Identifying Target Signals

Metallic targets produce 'solid', sharp, symmetrical signals. Ground noises are broad and uneven. If unsure, scrape a shallow hole and sweep the coil; if the signal decreases, it's likely ground noise. If it remains or increases, it's a metallic target. A 'halo effect' can make objects appear larger; this reduces once the object is disturbed.

Recovering the Target

Dig a small hole to recover targets. Clear loose material first. Digging carefully, especially for deep targets, prevents damage. Always refill holes and restore the area. Take away any rubbish recovered.

Pinpointing

To pinpoint, confirm the target signal after ground balancing. Sweep the coil, noting the strongest signal area. Draw an imaginary line. Repeat at 90 degrees. The intersection is the target location. Pinpointing may be off-center in 'M' or 'Cancel' modes.

Covering the Search Area

Use a snaking search pattern, moving forward slowly. Search the area from three different directions for thorough coverage. Overlap each sweep to ensure no area is missed.

Parallel Sweeping Procedure

Sweep the coil side-to-side, keeping it parallel and at a consistent height above the ground. Avoid raising the coil at sweep ends to maintain detection depth.

Motion Detection

The GP 3000 is a motion detector; the coil must be moving over a target to detect it.

Detector Sounds

• Threshold: Background sound set by Threshold and Tone controls.
• Target Signal: Abrupt change in threshold tone/volume when a target is detected.
• Ground Noise: Irregular noises from mineralisation, reduced by Tracking.
• Tune Indication: Beeps indicate successful frequency selection.
• Low Battery Indication: Pulses signal low battery.

User Information

Technical Specifications

Details include length (1100-1300mm), weight (2400g), transmit frequency, Dual Voltage Technology (DVT), automatic ground balance, motion detection, and various control functions (Power, Boost, Threshold, Volume, Signal, Tone, Tune, Level Adjust, Iron Discriminate, Soil, Coil, Balance). Audio output is a 6.35mm headphone socket. Headphones are supplied. Battery is 6VDC 12A/hr sealed lead acid, providing 14-15 hours of use.

Troubleshooting

Guidance is provided for common issues:

• No sound: Check Threshold, Volume, power cable, connections, headphones, battery.
• Threshold but no target signal: Check coil connection, try different coils.
• Random noises: Check for interference, re-tune, charge battery, use 'Cancel' coil setting, re-ground balance, check for thunderstorms.
• Battery not charging (vehicle): Check vehicle socket power, fuse, try alternative charger.
• Battery not holding charge: Check power cable, try alternative charger.
• Very noisy threshold: Check for interference, re-tune, try different location, use 'Cancel' coil setting.

Service Repair Form

A form is provided for returning the detector for service, requiring details of the fault, owner information, detector model, serial number, purchase details, and faulty parts.

Warranty

The GP 3000 control box has a 2-year warranty (parts and labour). Coils have a 1-year warranty. Warranty covers defects from purchase date but excludes damage from accident, misuse, neglect, alteration, or unauthorized service. The warranty registration card must be returned within 14 days of purchase.

Accessories

Available accessories include different search coils (e.g., 1100 and 1800), spare batteries (12A/hr and lighter 4.5A/hr), and corporate clothing.

Glossary of Common Terms

Definitions are provided for terms such as Control Box, Discrimination, Double D Coils, Electromagnetic Field, False Signal, Ferrous Metals, Ground Balance, Halo Effect, Hot Rocks, Interference, Mineralised Ground, Monoloop Coils, Non-Ferrous Metals, Pinpoint, RX, Search Coil, Search Pattern, Salt, Target Response, Target Signal, Tracking, and TX.

Contact Minelab

Contact Minelab via authorized dealers or write to Minelab Electronics Pty Ltd (Australia), Minelab USA, or Minelab International Limited (Ireland). Visit http://www.minelab.com for more information.