Greenlee / A Textron Company
3
4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070
SF-420AC
Working with Different Materials
The SF-420AC is for use on dry, interior walls only. Although the unit can scan
through up to 38 mm (1-1/2") of common construction materials in DeepScan
mode, three primary factors can affect sensing depth: thickness, density, and
moisture content.
This unit can scan effectively through most sheet materials, including:
• Bare wood flooring (in DeepScan mode)
• Linoleum on wood base
• Gypsum drywall over plywood sheathing
• Wallpapered walls (if dry)
• Textured ceilings if uniform thickness (Place a thin piece of cardboard on
ceiling and scan through it to avoid damage to texturing.)
The SF-420AC is not designed to scan materials with inconsistent density
such as:
• Ceramic floor tile
• Carpeting and padding
• Wallpaper with metallic fibers
• Freshly painted walls that are still damp (must dry at least a week)
• Lath and plaster walls
• Foil-covered insulation board
Note: Sensing depth and accuracy can vary due to moisture content of
materials, wall texture, and paint.
Troubleshooting
Specifications
Battery Type: 9 V alkaline
Estimated Battery Life: 1 year at 10 minutes per day with alkaline battery
SF-420AC Position Accuracy:
Stud Scan Mode: Typically within 3 mm (1/8") using the dual scan and
mark procedure
DeepScan Mode: Typically within 5 mm (3/16") using the dual scan and
mark procedure
SF-420AC Detection Depth:
Stud Scan Mode: Typically up to 19 mm (3/4")
DeepScan Mode: Up to 38 mm (1-1/2")
Note: Sensing depth and edge detection can vary due to moisture content
of materials, wall texture, paint, etc.
AC Position Accuracy: Typically 90 V to 250 V at 50 Hz to 60 Hz within 150 mm
(6") of a hot unshielded wire
AC Sensing Depth: In typical drywall with Romex
®
wiring, wires can be
detected up to 76 mm (3") deep
Note: Sensing depth and position accuracy can vary due to moisture
content of materials, wall texture, paint, etc.
Operating Temperature: –7
°
C to 49
°
C (20
°
F to 120
°
F)
Storage Temperature: –29
°
C to 66
°
C (–20
°
F to 150
°
F)
Humidity: 80% RH (noncondensing)
Situation
Probable Causes
Solutions
• Turn unit off, move over a few inches, press On/Off button, and start
again.
• On rough surfaces, place piece of paper on wall, scanning through it to
help slide unit more smoothly.
• Keep hand at least 152 mm (6") from tool while you calibrate and scan.
Hold unit with thumb and index finger no higher than handgrips. Be
careful not to move your fingers after calibration.
• Always hold unit parallel to and move perpendicular to object you're
trying to locate.
Lights start flashing and unit
starts beeping.
• Scan began on dense part of wall or over a
stud.
• Unit not flat against wall.
• Unit tilted or lifted during scan.
(All these factors affect proper calibration.)
• Interpret red LED closest to center as stud edge.
• Switch to DeepScan to locate the stud.
Center green LED doesn't light in
Stud Scan mode.
Wall is particularly thick or dense.
• Hold unit so two Velcro™ strips on the back make contact with wall.
• Recalibrate unit in a different place and rescan area.
The green TruCal LED lights but,
when scanning, unit doesn't do
anything else.
• Unit may not be flat against the wall.
• If it is in the DeepScan mode (the DeepScan
LED is lit), you may have calibrated over a
stud.
Scanning surface is too dense or too wet for unit
to operate.
All three red LEDs and green LED
light at the same time and unit
beeps continuously.
If you are using unit on a recently taped, painted, or wallpapered wall,
allow time to dry and try again.
Working in DeepScan mode and
can't detect studs.
• You may have calibrated over a stud. (The
error condition is disabled in DeepScan mode
because it is twice as sensitive as Stud Scan.)
• You may be holding the unit like a TV remote,
aiming it at the wall.
• Move unit over a few inches and recalibrate.
• Hold unit so two Velcro strips on the back make contact with wall.
Detects other objects besides
studs.
Electrical wiring and metal or plastic pipes may
be near or touching back surface of wall.
• Remember that studs or joists are normally spaced 406 mm (16") or
610 mm (24") apart and are 38 mm (1-1/2") wide.
• Always turn off power when cutting, nailing, or drilling near electrical
wires.
• See above solution.
• Use extra caution if the area has plywood, thick wood backing behind
drywall, or thicker-than-normal walls.
• If a switch controls an outlet, make sure it is on for detection, but
turned off when working near electrical wires.
You suspect electrical wires, but
do not detect any.
• Wires may be shielded behind metallic wall
coverings, plywood shearwall, or other dense
material, or in conduit; unit may not be able to
find them.
• The wires may not be hot.
• Wires may be too deep to sense.
To narrow detection, turn unit off and on again at the edge of where wire
was detected and scan again.
Area of voltage detection is too
large.
Static charge may develop on drywall, spreading
voltage detection as much as 305 mm (12") from
each side of an actual electrical wire.
