Schonstedt's GA-52Cx Operations Manual (2024)

Introduction

Schonstedt’s GA-52Cx Magnetic Locator detects the magnetic field of ferromagnetic objects and responds to the difference in the magnetic field between two sensors spaced approximately 20″ apart. This difference is referred to as the “signal strength” throughout this manual and is represented in the instrument by an audio tone.

Figure 1 illustrates an application of the GA-52Cx locator in which it is used to detect an iron marker used for property line identification. As shown, the magnetic field of the iron marker is stronger at sensor A than it is at sensor B. This creates a signal strength that is larger than zero (which would occur when the field strength is the same at both sensors). The audio response of the GA-52Cx is designed so that the frequency of the audio tone increases as the detected signal strength increases. As a result, the frequency of the audio output is higher than the idling frequency that exists when the signal strength is approximately zero.

Turn-On, Sensitivity and Volume Settings

Set the On-Off/Sensitivity Control to position 2 and adjust the Volume Control until the idling tone reaches a desired level. The sensitivity of the unit can be increased (to detect smaller objects at greater depth) or decreased (to detect larger objects at smaller depths) by adjusting the On-Off/Sensitivity Control. Setting the Sensitivity Control to position 2 provides what is referred to as the “Normal Operating Range.” Positions 3 to 5 increase the sensitivity; position 1 decreases the sensitivity.

The locator can be oriented in any direction without producing a significant change in the frequency of the tone from its idling frequency. When using headphones, the Volume Control has no impact on the output level of the audio signal.

Searching for Underground Targets with a Schonstedt GA-52Cx

Turn the instrument on, set the sensitivity control to position 2 (Normal Range), and grasp the locator. Because the upper sensor is located near where the locator is usually held, wristwatches may produce unwanted changes in the tone’s frequency. Remove your wristwatch, or hold the locator in the other hand. Keep the locator away from your shoes since they may contain magnetic material. To obtain the maximum area of coverage, the locator should be swept from side-to-side. When the locator comes within range of an object, you will hear an increase in the frequency of the output signal.

Basic Signal Patterns

After you detect the presence of a target, hold the locator vertically, and slowly move it back and forth in a “X” pattern while listening to the audio response. The audio peak will occur when the locator is directly over a vertical target, or it will occur over the ends of a horizontal target. The “X” pattern is ideal for pinpointing small objects. By using this technique, a 1-1/4 inch PK nail buried up to 12 inches can be precisely located.

If you are looking for a corner marker and detect two or more signals in the same general area, raise the locator several inches above the ground or decrease the gain setting. Any signal that disappears when the locator is held higher or the gain is decreased is probably coming from a smaller target. As shown in Figure 6, the signal from a rusty bolt or other small item decreases faster with distance than the signal from a larger target, such as an 18-inch length of 3/4 inch rebar that can be located at depths up to 9 feet.

Strongly Magnetized Markers

A strongly magnetized marker at or near the surface may provide location information that is misleading. The heavy line in Figure 7 represents the variations in tone frequencies when the locator is moved over the marker. When moving the instrument from A to B, the frequency of the tone increases and then decreases suddenly at B. From just beyond B the frequency of the tone increases sharply, becomes very high directly over the marker and decrease just before reaching C. From C to D the pattern is the reverse of that from A to B. It is obvious that the locator must enter the B-C region. Otherwise the marker might be assumed to be between A and B, or C and D. This phenomenon is explained by the fact that the locator is sensitive to the magnetic field components parallel to its long axis. At points B and C the field is perpendicular to the locator so no high frequency is produced at these points.

Locating Manholes, Septic Tanks, & Well Casings

The magnetic field is strongest at the edge of a shallow manhole cover. You can easily trace the edges of covers near the surface. The locating depth for manhole covers ranges up to 10 feet.The great length of a well casing provides a strong field at the surface that makes it easy to locate casings buried up to 18 feet deep.

The GA-52Cx can be used to precisely locate the metal handles or reinforcing bars on septic tank covers at depths of up to 4 feet.

Locating Objects under Snow or Water

The locator can be used in flooded areas, but keep the electronic unit out of the water. Snow poses no problem; thrust the locator into the snow as deep as necessary to locate the target.

Locating and Tracing Barbed Wire

You can often trace barbed wire from old fence lines buried just beneath the surface. Even if the wire is only a trail of rust, it can still be detected near the surface. Tip the locator a little lower than usual (but not parallel with the ground). First, examine trees for bench marks and bits of embedded barbed wire. Then hold the locator parallel with the direction of the wire.

Searching Areas Along a Chain Link Fence

Searching in the vicinity of a chain link fence requires a reduced sensitivity setting and some control over the orientation of the locator. Position the locator horizontally with its long axis perpendicular to the fence. This ensures that the upper sensor is kept away from the fence.

Perform the search by slowly moving the locator forward along the fence while also moving it to the right and to the left. As you move forward, this technique will allow you to search an area several feet wide. Listen for an abrupt drop in the signal that will occur when the lower sensor, located 1-5/8 inches from the end of the locator, is directly over the stake. Any variation in the position of the locator will produce an abrupt rise in the frequency of the signal.

Locating Valve Boxes

Both the valve and its casing, when iron, provide strong magnetic fields that make them easy to locate. Plastic enclosures containing magnets are easily located at depths of 10 feet or more.

Locating Cast-Iron Pipes

Cast-iron pipes produce the strongest magnetic signals at their joints.

After an initial sweep search identifies the general direction of the pipe, the steel pipe joints or transition points can be more accurately traced by the following procedure:

1. Set the sensitivity control to maximum.
2. Hold the locator vertically approximately 1 to 1-1/2 feet above the surface.
3. Walk without turning or tilting the locator.
4. Mark the locations where the maximum signal levels occur.
5. Return to an area of maximum signal strength and hold the locator several inches above the surface. The sensitivity will probably have to be reduced during this second pass. Four-inch pipes can be located at depths of up to 10 feet.

Locating Steel Drums

The GA-52Cx’s signal pattern will vary depending on the vertical or horizontal orientation of the drum and how deep it is buried. A 55 gallon drum can be located at depths of up to 10 feet.

Military & Hazmat Uses

1. The military and many local and state police departments use the GA-52Cx to detect buried ordnance and discarded weapons.
2. People drilling in an area where hazardous materials might be encountered use the GA-52Cx to search the area prior to drilling. Other Schonstedt magnetometers are available that can be lowered down the hole for periodic checks as drilling progresses.

Other Notes

1. A burbling sound indicates the presence of an energized power line.
2. The instrument will not detect non-ferrous metals, such as gold, silver, copper, brass and aluminum.

The GA-52Cx is designed and built to give trouble-free operation. Normally, maintenance is limited to the occasional replacement of batteries. In the event that a malfunction does occur, refer to the Troubleshooting Guide. The guide lists a few problems that can generally be corrected in the field so that you can continue using the locator without interruption.

Replacement of Batteries

The GA-52Cx is powered by two alkaline 9-Volt batteries. Alkaline or lithium batteries may be used. The batteries are carried in the battery holder. Access to the batteries is obtained by removing the two knurled nuts and sliding off the cover. Always replace both batteries.

CAUTION: When replacing the batteries hold the instrument by the metal chassis to avoid any contact with the printed circuit board and its components.

Troubleshooting Guide

If your locator needs service, please return it to the Schonstedt factory (in its case) and complete a Repair Form with the following information:

• Name
• Address
• Telephone and Fax Numbers
• Email Address
• Where Purchased
• Date of Purchase
• Description of Problem(s)
• If unit is out of warranty, an estimate will be provided prior to service work being done.

For Service or Repairs, Ship locator to:

Schonstedt Instrument Company

100 Edmond Road

Kearneysville, WV 25430

Schonstedt Instrument Company (Schonstedt) warrants each product of its manufacture to be free from defects in material and workmanship subject to the following terms and conditions. The warranty is effective for 7 years* after the shipment by Schonstedt to the original purchaser. Please complete the warranty registration card and send back to Schonstedt Instrument Company.

Schonstedt’s obligation under the warranty is limited to servicing or adjusting any product returned to the factory for this purpose and to replacing any defective part thereof. Such product must be returned by the original purchaser, transportation charges prepaid, with a description of the defect in writing. If the fault has been caused by misuse or abnormal conditions of operation, repairs will be billed. Specifically, this warranty does not cover product that has been subject to inundation by fire, water or other liquid intrusion, or units that have been damaged or compromised due to repair, alteration or modification by anyone other than an authorized repair representative. Prior to a repair being performed by Schonstedt, a cost estimate will be submitted and no work will be completed until authorized by the customer. Batteries are specifically excluded under the warranty and should be addressed to the manufacturer of batteries in question.

Schonstedt shall not be liable for any injury to persons or property or for any other special or consequential damages sustained or expenses incurred by reason of the use of any Schonstedt product.

* For Military & EOD applications, the warranty is 1 year.

Parts and accessories are available on shop.schonstedt.com. Use the links below to visit the listing in our store. If you need help, please contact Customer Care.

Important notice

Schonstedt believes the statements contained herein to be accurate and reliable; however, their accuracy, reliability, or completeness is not guaranteed. Schonstedt's only obligation shall be to repair or replace any instrument proven to be defective within one year of purchase. Schonstedt shall not be responsible for any injury to persons or property, direct or consequential, arising from the use of any instrument.