Schonstedt Instrument MAC-5lB User manual

Instruction Manual
Model MAC-5lB
I ' . r' and Cable Locator E
^\,Iagnetrc an(l uaore Locato i
E
Manufactured By
Schonstedt Instrument Company
1775 Wiehle Avenue
Reston, Virginia 22090
[phone]
TWX: 710-833-9880
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Printed May 1985

TABLE OF CONTENTS
Section I General
Introduction
Cable Locator Mode.
Magnetic Locator Mode.
Standard Accessories.
Transmitter, Turn-On and Battery Check. . . .
Transmitter, Inductive Mode.
Transmitter, Conductive Mode.
Transmitter, Inductive Signal Clamp Mode.
Receiver, Function Selection and Turn-On. . . . .
Receiver, Sensitivity Settings
Tracing, Inductive Mode.
Tracing, Conductive Mode.
Section V Cable Locator Application Notes
Inductive Coupling.
Page
1-l
1-l
1-l
r-2
Receiver Compatible with Metrotech Model 480. . . . . . l-2
Specifications.... l-2
Section II Magnetic Locator Operation
Theorv of Ooeration.
Function Selection, Turn-On and Initial Setting
Low Sensitivitv Operation.
High Sensitivity Operation. . .
Search Procedure.
Section III Magnetic Locator Application Notes
Basic Sisnal Patterns
Strongly Magnetized Markers
Locatlig Maiholes, Septic Tanks and Water Wells. . . .
Locating Objects Under Snow or Water
and Tlacinq Barbed Wire. .
Searchins Areas Along a Chain Link Fence.
Locatins-Valve Boxes.
Locatins Cast-I
Other Notes. .
ron Pipes
Section IV Cable Locator Operation
Theory of Operation.
2-r
oo
oo
2-3
2-3
Lt- L
3-2
J-J
3-4
J-D
3-6
3-6
3-6
Conductive Couplin
Dealing with Clutter Signals.
Single-Lobe Identification. . . . .
Bends and Junctions.
4-r
4-2
ZT-J
4-3
4-4
4-4
4-5
4-5
4-6
5-l
5-1
5-2
D-J
D-J
5-4
Signal Spreading.

Section V Cable Locator Appiication Notes (cont.) Page
Magnetic Locator Function 5-4
Isolators and Signal Path Continuity. . .
Isolators and Inductive Excitation. . . . .
Isolators and Conductive Excitation. . . 5-6
Determining Target Depth by Triangulation. . 5-6
Section VI Maintenance
Replacement of Receiver Batteries
Replacement of Transmitter Batteries. . . .
Receiver Troubleshootins Guide
Transmitter Troubleshootins Guide.
Servicelnformation ......
Warranty
5-4
D-D
6-I
6-3
6-4
6-4
6-4
6-7
LIST OF FIGURES
Title
MAC-518 Magnetic and Cable Locator
Detecting Magnetic Field of an Iron Marker. . .
Sensitivity Set for Normal Range
Sensitivity Set for Low Range.
Sensitivity Set for High Range
Searching with the Locator
Signals from Vertical and Horizontal Targets. .
'X' Pattern Provides Precision Locatins.
Raising the Locator Eliminates Unwanted
Signals
Signal Pattern From a Strongly Magnetized
Marker.
Locating Manhole Covers
Locating Water Well Casings. . . . .
Signal Pattern Provided by Septic Tank
Handles
3-8 Locating Oblecis ""a"t Sno* o, #ut*. . . . . . .
3-9 Tracing Barbed Wire from Old Fence Lines. . .
3-I0 Searching in the Vicinity of a Chain Link Fence
3-i1 Placement of Locator While Searching
AlongaChainLinkFence. .........
3-12 Locating Valve Boxes
3-13 Signal Pattern Provided by Cast-Iron Pipes. . . .
4-I Transmitter and Receiver Placement
4-2 Signal Pattern from a Tracing Signal
Figure
l-t
2-L
00
z-J
o^
z-D
3-I
3-2
3-3
.t-4
J-D
3-6
o-/
Page
1-1
2-).
2-2
oo
2-3
2-3
3-l
3-l
3-2
3-2
J-.'
J-J
.r-.J
.t-4
3-4
!t-D
J-O
3-6
3-6
4-l
4-2
lll

Figure
LIST OF FIGURES (cont.)
Title
Transmitter Controls
Transmitter Operating Positions
Transmitter Hookup for Conductive
Operation
Inductive Signal ClamP HookuP
Sensitivity Set for Normal Range.
Null Shape Versus Sensitivity Setting.
Inductive Mode Tracing. . . '
Conductive Mode Tracing. . , . .
Inductive Coupling SetuP.
Conductive CouPling SetuP.
Repositioning Transmitter to Reduce
Interference
Sinsle Lobe Identification Technique
Identification of Bends andJunctions. . . . . . . . .
Gas Line Isolator Bypassed with Shorting Wire
Pedestal with Grounding Clip Installed.
Pedestal with Groundwire Removed. . .
Determining Approximate Depth of Target' ' '
Page
L-9
4-3
4-3
4-4
4-4
4-D
4-6
6-l
6-2
o-t)
6-5
6-6
4-3
4-4
4-5
4-6
4-7
4-B
4-9
4-10
5-I
5-2
D-O
5-4
D-D
5-6
D-/
5-8
5-9
4-6
D- t-
5-2
5-2
D-.t
o-J
D-D
D-D
b-b
D-1
6-I Exploded View of Receiver Electronic Unit ' ' '
6-2 Replacement of Receiver Batteries
6-3 Replacement of Transmitter Batteries' ' ' ' ' ' ' '
6-4 MAC-slB Receiver Repair Parts. '
6-5 MAC-SIB Transmitter Repair Parts '
IV

Section I
General
Introduction
The MAC-5lB Magnetic and Cable Locator is a light-weight, dual-
mode instrument designed for detecting buried iron and steel objects
and tracing underground cables and pipes. The system consists of two
major units: a transmitter and a dual-function receiver. Both units
use C-cell batteries that provide up to 50 hours of operation.
Cable Locator Mode
When used in the cable locator mode, the transmitter generates a
distinctive ac signal which is applied to the cable or pipe, The receiver
is used to detect and trace the signal as it travels along the cable/pipe.
A siren-like tone from the receiver is easily identified as the tracing
signal. The approximate depth of an underground cable can be
determined using the 45' null-point triangulation method. Operation
of the MAC-5IB in the cable locator mode is explained in Sections IV
and V,
Magnetic Locator Mode
The receiver is the only unit required for operation in the magnetic
mode, Set the receiver M/C function switch to "M". adiust the
sensitivity control, and you have the best magnetic locator available.
Operation of the magnetic locator mode is explained in Sections II
and III.
Switching from cable locator mode to magnetic locator mode while
tracing a cable is a unique method for unscrambling ground clutter.
Gas and water pipes in the immediate vicinity of a cable can emit
parasitic signals that distort the identification null. In the magnetic
mode cast-iron water pipes and gas lines can be identified quickly and
even classified as to type by the conventional spacing of joints, which
provide the strongest signals.
Figure 1-1. MAC-578 Magnetic and Cable Locator
1-l

Standard Accessories
Basic accessories supplied with the MAC-SIB include an earphone
jack, a spare batteries holder and a conductive cable assembhl with
ground stake. An inductive signal clamp and earphon"r ur" urruilubl"
as options.
Receiver Compatible with Metrotech* Model480
The 82.5 kHz tracing signal detected by the MAC-blB receiver in
the cable locator mode is the same frequency used by the Metrotech*
Model480-Pipe and Cable Locating System. The MAC-51B receiver,
available from Schonstedt Instrument Company as a separate unit,
can be used as a direct replacement for the Metrotech 480 receiver in
conjunction with the Model480 transmitter.
-[{"tt.t""h t, a registered trademark of Metrotech Corporation
SPECIFICATIONS
TRANSMITTER
Operating Voltage
Battery Life
Output Frequency
Audio Indicator
Weight
Operating Temperature
Overall Size
RECEIVER
Operating Voltage
Battery Life
Output Frequency
Weight
Operating Temperature
Overall Length
12 Volts (eight C-Cell batteries)
50 hours intermittent operation at 70o F
82.5 kHz modulated at 382 Hz. nulsed
at 4,8 Hz (inductive or conductive)
2.58 kHz pulsed at 4.8 Hz
Approximately 5.5 lb.(2.5 kg.)
0o F to 120' F (-18' C to 49' C)
43.5 in. x 7 in. x 5 in. (110.5 cm. x l7.B
cm. x 12.7 cm.)
6 Volts (4 C-Cell batteries)
50 hours intermittent operation at 70' F
Approximately 40 Hz idling tone from
speaker, Frequency ofpulsing tone in-
creases (ot decreases) with signal
intensity.
Approximately 3 lb. (1,36 kg.)
0o F to 120' F (-18" C to 49. C)
42.3 in. (107.4 cm.)
I-2

SPECIFICATIONS (cont. )
RECEMR (cont.)
Waterproof Length 34.5 in. (87.6 cm.)
Nominal Sensor Spacing 20 in. (50.8 cm.)
(Specifications subject to change without notice)
PATENTS
Manufactured under the following patents: United Statesr 2,916,696;
2,981,885; 3,894,283; 3,909,704; 3,96I,245; 3,977,07 2; 4, I 10,689;
4,161,568; 4,163,877; 4,258,320 and Design 255552. Canadar
637,963; 673,375; 1,006,915; 1,037,121; and 1,141,003. Great
Britain: I,446,741; 1,448,742 and 1,494,865. France: 2.205.67L
Germany: 25 51 968,0-09; 23 55 630; and 29 01 163. Other United
States and foreign patents pending.
1-3

Section II
Magnetic Locator Operation
Theory of Operation
In the magnetic locator mode, the MAC-SIB receiver responds
when the magnetic field strength at the two sensors, which are 20
inches apart, is different. This response consists of a change in the
idling frequency of the signal emitted from the speaker.
Figure 2-l illustrates an application of the locator in which it is
used to detect an iron marker of the type used for property line
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 on the
speaker is higher than the 40 Hz idling frequency which exists when
the fieid strength is the same at both sensors.
q
O
eo
a
O
o
SENSOR A
\ \--lr, o 1\-/
d\ O IRON MARKER O
Figure 2-1. Detecting Magnetic Field ot' an lron Marker
ol

Function Selection, Turn-On and Initial Sensitivity Setting
Set the M/C Function switch to M and adiust the ON/OFF-
Sensitivity control for mid-position as shown in Figure 2-2. With the
knob in this position, the sensitivity is set for what is referred to as the
Normal Range,
In most areas the locator can be oriented in any direction without
producing a significant change in the frequency of the tone from its
idling rate. However, in some areas where magnetic disturbances are
encountered from nearby structures, rocks, sand or trash, the control
should be adjusted for lower sensitivity as illustrated in Figure 2-3.
ON /OFF
SENSITIVITY
M/C FUNCTION
swtTcH
EARPHONES JACK
Figure 2-2. Sensi,ti.aity Set Jor Normal Range
Low Sensitivity 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 sensitivity knob in a counter-clockwise
direction. Reduced range is useful for pinpointing the location of a
strongly magnetized marker.
Figure 2-3. Sensitiuity Set Jor Lou Range
oo

High Sensitivity Operation
. T-hq sensitivity of the locator is increased by turning the sensitivity
knob in a clockwise direction. A high sensitivity setting imposes some
constraints _on operating rnethods. The locator tone will vary in
frequency depending on the instrument's orientation relative to the
Earth's masnetic field.
Figure 2-4. Sensitiaity Set Jor High Range
Search Procedure
Set the sensitivity control for normal operation and hold the locator
just below the large end as illustrated in Figure 2-5. Because the
upper sensor is Iocated near the area where the locator is usually held,
wrist watches may produce unwanted changes in the signal
frequency, Therefore, a watch worn on the the wrist of the hand
holding the locator should be removed. Avoid bringing the locator
close to your shoes, since they might contain magnet-ic iraterial.
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-und. A higher frequency tone from the speaker wili be heard
when the locator is within range of an iron or sieel obiect,
When using a high sensitivity
setting, avoid turning thelocator
about its long axis, This may
produce tonal variations in the
output signal because of sensor
misalignment.
The presence of a ferromaq-
netic object will be indicated by
a change in the tone of the out-
put frequency.
Figure 2-5. Searching uith the Locator
2_3
w

Section III
Magnetic Locator Application Notes
Basic Signal Patterns
il srcNAL FoR A
ll vERilcALLY
ll oRrENrEo
ll TARGET - GREATEST
ll * ovERroP
ll /\
_ f __-/'
SIGNAL FOR A
HORIZONTALLY
ORIENTED TARGET _
+ GREATESTOVERENDS
aoo
ooo n o_o A
-llO
^(-'oil^
, o -- ouo '_-4 o
O
o. e o_:__c__:__: o -o-
3r: "7,C; :2-::
Figure 3-1. Signals from Vertical and Horizontal Targets
After you have detected the presence of a target, hold the locator
vertically and move it back and forth in an "X" pattern. The peak
signal occurs directly over a vertical target, and over the ends of a
horizontal target.
The "X" pattern is ideal for pinpointing small objects, A 1-1/4-inch
PK nail buried up to 8 inches can be located so precisely with this
technique that it can be uncovered using a l/2-inch star drill.
./
-.
Prooides Precision Locatine
If you find more then one signal in the vicinity of a target, just raise
the locator several inches higher. Any signal that disappears when the
locator is raised is probably not coming from the actual target. The
signal from a rusty bolt or other small item will decrease much faster
with distance than the signal from a larger target such as a corner
marker. An l8-inch length of 3A-inch pipe can be located at depths up
to 7 feet.
3-i

SIGNAL ABOVE GROUNO
SIGNAL AT GROUND
"Jo 4"1-a oo o o
cla sMALLron O D oq -
"'3 o'o a o eo t-
o o oo I o o
Oll.oo
coRNERMARKER | | O
o ll '
o -= o-l,J
Figure 3-3, Raising the Locator Elirninates (Jnuanted Signals
Strongly Magnetized Markers
A strongly magnetized marker at or near the surface may provide
location information that is misleading.
The heavy line in Figure 3-4 represents the variation in tone
frequency when the locator is moved over the marker. When moving
the instrument from A to B, the frequency of 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 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.
Figure 3-4. Signal Pattern From a Strongly Magnetized Marker
3-2

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 and Water Wells
The magnetic field is strongest at the edge of a shallow manhole
cover. Turn the sensitivity down all the way and you can easily trace
theedge ofcovers near thesurface, Locating depth ranges up to 8 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 15 feet deep.
Figure 3-6, Locating Water
WelI Casinss
The MAC-SIB receiver can be used to precisely locate the metal
handles or reinforcing bars on septic tank covers at depths up to 4 feet.
Figure 3-7. Signal Pattern Prouided bg Septic Tank Handles
3-3
Figure 3-5. Locating
Manhole Cooers
o.o

Locating Objects under Snow or Water and Tracing Barbed Wire
The locator can be used in flooded areas-just 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.
,')
\,
-_.-_ l\/
sNowBANK /\
//\
//
,/,/
a
o_So,o
o-ll "^ oo"^
b" 1|1"3. * ". o"
Figure 3-8. Locating Obiects 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 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 Iocator narallel with the direction of the rvire.
,at''
)*: -'a*Jt4*-A.,4-*
{;'OoDoeu
Pt Po,
^)
"o
Figure 3-9. Tracing Barbed Wire Jrom Old Fence Lines
tf
1
*-r-=z:,n i,-rvev^-
i
l+i
-l-- ll-.- , ,iii
*-'{--=:.-=-.-:-U L=4
oo ' fllt-Q- =-'
c-=---ll:-.--
3-4

Searching Areas Along a Chain Link Fence
Searching in the vicinity of a chain link fence requires a reduced
sensitivity setting and also some control over the orientation of the
locator. As illustrated in Figure 3-10, position the locator horizontally
with its long axis perpendicular to the fence. This ensures that the
upper sensor is kept away from the fence.
Fi.gure 3-10. Searching in the Vicinity oJ 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 from 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 frequency of the tone.
^6>(
:lT^1'"['^'JSllil, -
\
- -.a-^--r-r---3--/- ---ltt-- )L-
+ " b ,--u -i
l<-1-5r8" €, O
c)--f'n.'oeo
Aoo o o() ll.-. o- o
sG:o'ooll .Oo€o
Figure 3-ll. Placement oJ Locator Whi,Ie Searching Along a
Chain Link Fence

Locating Valve Boxes
Both the valve and its casing,
when iron, provide strong mag-
netic fields which make them easy
to locate. Plastic enclosures con-
taining magnets are easily' Iocated
at depths of 6 feet or more.
Figure 3-12. Locating Valoe
Boxes and Casings
Locating Cast-Iron Pipes
As illustrated in Figure 3-13, cast-iron pipes produce the strongest
magnetic signals at their joints.
I
:i
I ',.,*rar, fi
I I l\
rl -L l\ /L
_li I
-O' -Q o J 5 -Z'-5' <, o )--c' -
Figure 3-13. Signal Pattern Propided by Cast-Iron Pipes
The initial search should be performed as follows:
1, Adjust the sensitivity Ievel for maximum.
2. Hold the locator vertically approximately 1 to l-Il2 feet above
the surface.
3. Walk along 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
Iocator 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 up to B feet,
Other Notes
L A burbling sound indicates the
line,
2, The instrument will not detect
gold, silver, copper, brass and
presence of an energized power
nonmagnetic materials such as
aluminum.
ao -' 4 ^
'S o "'" o"
O.
lo o^Yo
lo o-.o
3-6

Section IV
Cable Locator Operation
Theory of Operation
In the cable locator mode, the receiver must be used in
combination with the transmitter which is housed in the carrying case.
As illustrated in Figure 4-1, the transmitter is placed over and in
line with the target cable/pipe. An alternating current induced into
the cable/pipe produces a signal that is detected with the receiver.
The transmitter emits a steady beeping sound to indicate that it is
operating, and the receiver emits a siren-like sound that is easily
identified as the induced tracing signal.
Figure 4-1. Transmitter and Receiaer Placement
The tracing current generates an alternating circumferential field
around the cable. This alternating field induces a signal 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 decreases.
The heavy line in Figure 4-2 represents the increase and decrease in
pitch of the audio signal as the receiver is moved back and forth over
an energized cable, Moving from A to D causes the pitch to increase to
a maximum at B and decrease to a minimum directly over the target.
At C the pitch again increases and then decreases at D,
The MAC-SIB can be used to trace any long conductive element
such as an anode string or metalized warning tape as well as cable and
pipe.
il,ii.:1))
"to
lo
'/-
lo
f--
-
\ '-
o\ "
q\
o /^ / toi,\ -_\"C
ffi
T".\i./"t('i/ .",
t"j)*;/:c:
. 6 ,-u--_-.- o
u ', o tf
' o^ u o
n9A.
-a c. { 4
^1
a- I

?dL="#
9;\,,o"&
-\c
I CABLr
o
>\is
CABLE
.?
<-/'
F
. t....
>l
I
, ),,
l-'
Io
/<> I
-/ U
-\-i
-.(
-S-
-1,-
Figure 4-2. Signal Pattern Jrom a Tracing Signal
NOTE
For convenience, all targets will
be referred to as lines throughout
Sections IV and V.
Transmitter, Turn-On and Battery Check
Set the ON/OFF switch to ON and listen for a steady beeping
sound. If a beeping is not heard, the batteries must be replaced as
described on page 6-3.
CARRYING CASE
CONDUCTION
ACCESSORY
ON/OFF SWITCH JACK
TRANSMITTER
ELECTRONICS
Figure 4-3. Transmitter Controls
,to

Transmitter, Inductive Mode
The most common line excitation mode is inductive. With the cover
open and the arrow pointing up, place the transmitter over the line as
illustrated in Figure 4-4. The cover must be pointing up. Turn the
transmitter ON/OFF sw-itch to ON and you will hear a steidy beeping
sound, If not, replace the batteries.
Figure 4-4, Transmitter Operating positions
Transmitter, Conductive Mode
If an exposed section of a target gas or water pipe is accessible, the
tracing signal can be applied directly to the target line.
Plug the conductive cable assembly into the transmitter accessory
jack and !,urn the power _switch to ON, (Inserting the plug
automatically disables the inductive transmitter and applies exciting
current to the cable clips,) Connect one cable clip to i conductive
portion of the line. Drive the ground stake into the soil off to the side
of the line and attach the other clip to the stake. A good electrical
contact between the clips, the line, and the ground stake is very
important.
I
I
ii
tl
ir- CABLE
Figure 4-5. Transmitter Hookup Jor Conductiae Operation
4-3

Transmitter, Inductive Signal Clamp Mode
The inductive signal clamp (optional) provides a convenient
method of applying the tracing signal to electrical cables covered with
nonmetalic insulation. Plug the clamp lead into the transmitter
accessory jack, turn on the transmitter and close the clamp around
the cable. No ground connection is required. It can be applied to
cables up to three inches in diameter.
Figure 4-6. Inducti'rse Signal Clamp Hookup
Receiver, Function Selection and Turn-On
Set the M/C switch to C and adjust the ON/OFF-Sensitivity control
for mid-position as shown in Figure 4-7 . The volume level is preset. If
the receiver is turned on when located within 15 feet of the
transmitter, the receiver's speaker will emit a siren-like sound
indicating that the receiver is picking up the tracing signal directly
from the transmitter through the air.
The sensitivity will have to be increased as the distance between the
receiver and transmitter increases. Higher sensitivity is required when
operating in the inductive mode.
ON/OFF
SENSITIVITY
_l
l_
_t
M/C FUNCTION
swlTcH
EARPHONES JACK
Figure 4-7. Sensitit:i.ty Set Jor Normal Range
+-4
-l_
ffie#
<r\K-l"r
\\ \\ I IINCREASE