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Schonstedt Instrument MAC-51Bx, Instruction Manual, Page: 12 / 35

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Schonstedt Instrument MAC-51Bx Instruction Manual Download Page 12

Locating Manholes, Septic Tanks and Water Wells

The magnetic field is strongest at the edge of a shallow manhole cover.  Turn the Gain control to LO and you can easily
trace the edge of a cover near the surface.  Locating depth 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 MAC-51Bx receiver can be used to precisely locate the metal handles or reinforcing bats on septic tank covers at
depths up to 4 feet

Figure 3-7. Signal Pattern Provided by Septic Tank Handles

Schonstedt Instrument Company

3-3

Figure 3-5. Locating Manhole Covers

Figure 3-6. Locating Water Well Casings

OUTPUT SIGNAL

Summary of Contents for MAC-51Bx

Page 1: ...n Manual Model MAC 51Bx Magnetic and Dual Frequency Pipe and Cable Locator Manufactured by Schonstedt Instrument Company 4 Edmond Road Kearneysville WV 25430 Telephone 304 725 1050 Fax 304 725 1095 February 2000 ...

Page 2: ...d LO Modes 4 3 Conductive Signal Coupling For HI and LO Modes 4 3 Inductive Signal Coupling With Signal Clamp For HI Mode Only 4 4 Mode Selection 4 4 Gain Settings for Tracing a Cable or Line 4 5 Cable Tracing HI Mode Using Inductive Coupling 4 5 Conductively Applied Tracing Signals For HI and LO Modes 4 6 Section V Cable and Line Tracing Application Notes Inductive Signal coupling for Cable Line ...

Page 3: ...mitter Hookup For Conductive Coupling 4 3 4 6 Inductive Signal Clamp Hookup 4 4 4 7 Gain Setting for Normal Range 4 4 4 8 Null Shape Versus Gain Setting 4 5 4 9 Inductively Coupled Tracing Signals 4 6 4 10 Conductively Applied Tracing Signals 4 6 5 1 Inductive Coupling Setup 5 1 5 2 Conductive Coupling Setup 5 2 5 3 Conductive Coupling for Break Locating 5 2 5 4 Repositioning Transmitter to Reduce...

Page 4: ...t iron water pipes and gas lines can be identi fied quickly and even classified as to their type by the conventional spacing of joints which provide the strongest signals Cable Line Tracing HI LO Locating Modes The MAC 51Bx transmitter simultaneously transmits 571 Hz LF and 82 5 kHz HF signals When applied to any continuous metal conductor the HF trace signal jumps gaskets between pipe sections an...

Page 5: ...Hook up can be made to all continuous metal pipes and cables up to three inches in diameter Optional Mini Transmitter The Model MT 2 is a miniature transmitter 3 in x 1 in used in combination with a MAC 51Bx receiver to trace nonmetallic pipes pinpoint obstructions and locate concrete septic tanks The Receiver s Mode switch must be set to HI As the MT 2 Mole is pushed through a buried nonmetallic ...

Page 6: ...F to 140 F 25 C to 60 C Overall Length 42 3 in 107 4cm Waterproof Length 34 5 in 87 6 cm Nominal Sensor Spacing 20 in 50 8 cm Specifications subject to change without notice Schonstedt Instrument Company 1 3 NOTE The receiver s manual gain feature gives you a significant advantage in being able to adjust the sensitivity based on your expertise to optimize the locating and pinpointing of a wide ran...

Page 7: ...m the speaker Figure 2 1 illustrates an application of the locator in which it is used to detect an iron pipe marker of the type used for property identification The magnetic field of the marker is stronger at sensor A than it is at sensor B As a result the frequency of the signal from the speaker is higher than the 40 Hz idling frequency which exists when the field strength is the same at both se...

Page 8: ...red from nearby structures rocks sand or ferrous trash the control should be adjusted for a lower gain as illustrated in Figure 2 3 Figure 2 2 Normal Range Gain Setting Low Gain Operation Unwanted background signals due to nearby magnetic objects may require that the effective range of the locator be reduced This is accomplished by turning the Gain control towards LO Reduced range is also useful f...

Page 9: ...cator is usually held wrist watches may produce unwanted changes in the signal frequency Therefore a watch worn on the wrist of the hand holding the locator should be removed Avoid bringing the locator close to your shoes since the might contain magnetic material To obtain maximum area coverage the locator should be swept from side to side with the small end of the instrument kept close to the gro...

Page 10: ...ly with this technique that it can be uncovered using a 1 2 inch star drill Figure 3 2 X Pattern Provides Precision Locating If you find more then one signal in the vicinity of a target just raise the locator several inches higher this has the same effect as reducing the gain Any signal that disappears when the locator is raised is probably not coming from the actual target The signal from a rusty...

Page 11: ... the tone increases and then suddenly decreases at B From just beyond B the frequency of the tone increases sharply becomes very high directly over the marker and decreases just before reaching C From C to D the pattern is the reverse of that form 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 Figure 3 4 Signal...

Page 12: ... 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 MAC 51Bx receiver can be used to precisely locate the metal handles or reinforcing bats on septic tank covers at depths up to 4 feet Figure 3 7 Signal Pattern Provided by Septic Tank Handles Schonstedt Instrument Company 3 3 Figure 3 5 Locating Manhole Covers Fig...

Page 13: ...ting Objects Under Snow or Water 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 neat the surface Tip the locator a little lower than usual but not parallel with the ground First examine trees for benchmarks and bits of embedded barbed wire The hold the locator parallel with the direction of the ...

Page 14: ...s kept away from the fence Figure 3 10 Searching in the Vicinity of a Chain Link Fence Perform the search by moving along the fence keeping the end a constant distance from the fence When a point 1 5 8 inches form the end of the locator is directly over the stake the signal will drop abruptly as shown in Figure 3 11 Any variation in the position of the locator will produce an abrupt rise in the fr...

Page 15: ...ron Pipes The initial search should be performed as follows 1 Set the Gain control to HI 2 Hold the locator vertically 1 to 1 1 2 feet above the surface 3 Walk along without turning or tilting the locator 4 Mark the locations where the maximum signals occur 5 Return to an area of maximum signal strength and hold the locator several inches above the surface The gain setting will probably have to be...

Page 16: ... be encountered use the MAC 51Bx to search the area prior to drilling Other Schonstedt gardiometers 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 powerline in the MAG Mode 2 The instrument in the MAG Mode will not detect nonmagnetic items such as gold silver copper brass aluminum tin ...

Page 17: ... directly over the target conductor and peaks on each side Figure 4 1 Transmitter and Receiver Placement The tracing currents generate alternating circumferential fields around the conductor These alternating fields induce two signals into the receiver s sensor As the receiver is moved back and forth across the cable in a search pattern the pitch of the audio output from the receiver increases and...

Page 18: ...a beeping is not heard the batteries must be replaced as described on page 6 1 Figure 4 3 Transmitter Features Schonstedt Instrument Company 4 2 NOTE For convenience all targets will be referred to as lines throughout Sections IV and V ANTENNA TRANSMITTER ELECTRONICS CARRYING CASE ON OFF SWITCH ACCESSORY JACK INSIDE TOP BASE SENSOR SIGNAL PATTERN A B C D CABLE ...

Page 19: ...ve joint gaskets the LF signal only cannot be traced beyond the first joint from where the signal is applied Plug the conductive cable assembly into the transmitter s accessory jack and turn the power switch to ON Inserting the plug automatically disables the transmitter s inductive mode and applies the exciting current to the cable clips Connect one cable clip to a conductive portion of the line ...

Page 20: ...t the Mode switch to HI for tracing a line or pipe with an inductively coupled signal and when tracing beyond a break for verification purposes Set the Mode Switch to MAG for locating ferrous metal targets or for verifying an energized power line In the HI Inductive Mode you should move the receiver at least 20 feet away from the transmitter to start tracing to avoid picking up the HF tracing sign...

Page 21: ...de Using Inductive Coupling Position the transmitter over the target line and turn the power switch to ON A steady beeping will be heard that indi cates the transmitter is operational Move approximately 20 feet away from the transmitter along the suspected target line before you start to trace the signal This ensures that the receiver is not receiving the signal through air directly from the trans...

Page 22: ...ust physically connect the transmitter s output frequencies to an exposed metal section of the line using the conductive cable assembly and the ground stake After the two clips are connected to the line and to the ground stake good electrical contacts are essential the procedure for using the receiver is the same as for inductively coupled signals except that you can begin tracing right next to th...

Page 23: ... can hold the receiver horizontally near the ground as shown in Figure 5 5 and listen for a single peak audio signal which occurs directly over the target line You can also apply the tracing signal conductively and set the Receiver Mode switch to LO Figure 5 1 Inductive Coupling Setup Conductive Coupling for Cable and Line tracing in HI Mode This is the most reliable and best way to apply the stro...

Page 24: ...the ground as far off to the side of the line as the cable will permit The 571 Hz LF signal will not travel beyond a fault and will not bleed off onto adjacent cables lines and pipes As indicated in Figure 5 3 you can verify the type of target magnetic or nonmagnetic in the MAG Mode trace the cable using the LO Mode to locate the break where the signal disappears and continue tracing beyond the br...

Page 25: ...poor or leaky lines Figure 5 4 Repositioning Transmitter to Reduce Interference Single Lobe Identification HI Mode A second line parallel to the line being traced will emit a parasitic signal but at a reduced strength Interaction of these signals results in unequal side lobes which cause a large null off to one side of the target line as indicated by signal pattern curve A in Figure 5 5 To accurat...

Page 26: ...tion is prevalent when ground water is present The signal also spreads to nearby lines and into the soil itself When this situation is encountered the transmitter must be moved closer to the section of the line to be traced and the signal must be applied conductively if possible Signal spreading can also occur even when lines are well insulated The tracing signal can travel into buildings via the ...

Page 27: ...vanic current and reduces corrosion If you are inductively exciting this type of line by placing the transmitter close to the meter you must place a shorting wire on the pipe to bypass the isolator This allows the tracing current to return to the pipe through the earth ground of the building An alternate method is to move the transmitter down line a few yards away from the building to a point wher...

Page 28: ...o earth ground through the pedestal the trace current will use it to complete the return loop to the transmitter grounding stake instead of going down the target line So if there is a ground wire in place disconnect it from pedestal before connecting the conductive cable clip to the shield to ensure that a strong tracer current is applied to the cable Figure 5 9 Pedestal with Ground Wire Removed S...

Page 29: ...2 This measurement indicates the approximate depth of the target Figure 5 10 Determining Approximate Depth of Target Schonstedt Instrument Company 5 7 MARK SPOT 2 MARK SPOT 1 TARGET DISTANCE EQUALS DEPTH OF TARGET NOTE You should always take a depth reading on both sides of the line If the measured distances between spots 1 and 2 on both sides of the line are not the same there is a good chance th...

Page 30: ... is shipped with a spare set if lithium batteries stores in the carrying case Access to the batteries is obtained by removing the two knurled nuts and sliding off the cover Always replace both batteries Figure 6 1 Exploded view of Receiver Electronic Unit Replacement of Transmitter Batteries The transmitter is powered by eight alkaline C Cell batteries located in a battery holder Access to the bat...

Page 31: ...ment of Transmitter Batteries Schonstedt Instrument Company 6 2 SPARE BATTERIES USER SUPPLLIED BATTERY BOX TERMINALS REMOVE BATTERIES FROM ENDS OPPOSITE SPRINGS FIRST INSTALL BATTERIES AGAINST SPRINGS FIRST COIL SPRINGS ...

Page 32: ...k for corrosion Clean contacts Uncontrollable screaming Weak batteries Replace Symptom Possible Cause How to Check How to Fix Most battery manufacturers warranties cover the cost of repair or replacement of any device damaged by their batteries Removing batteries that leak will void their warranty No Sound Dead Batteries Batteries not making contact Broken wires Battery leakage Replace Check for c...

Page 33: ...REW MOUNTING 2 GROUND SPRING 2 SPEAKER MODULE BATTERY HOLDER BD ASSY COVER WITH LABEL KNURLED KNOB 2 CAP KIT WITH SCREEN SCREEN CRUTCH TIP BLACK CHASSIS INTERFACE CABLE ASSY H30006 208396 K20030 K20027 SMVIN6C500 208442 302301 208306 208369 K20021 207215 206006 208212 302284 208406 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ITEM PART NO DESCRIPTION ...

Page 34: ...FF BATTERY HOLDER COVER KNURLED NUT 2 BATTERY C TYPE 8 BATTERY CASE CONDUCTIVE CLAMP GROUND STAKE INDUCTION CLIP MINI TRANSMITTER MOLE BATTERY 9V LITHIUM 2 SPARE LATCH LATCH KEEPER 402320 302303 208431 208432 301674 205252 B11009 207315 302307 208263 301646 MT 2 B11014 L55002 1 L55002 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ITEM PART NO DESCRIPTION ...

Page 35: ...ping information will be furnished upon notification of the difficulty encountered Model and serial numbers must be supplied by the user Batteries are specifically excluded under warranty 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 PATENTS Manufac...

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