6
ENGLISH
Turning the Laser On
1.  Place the laser on a smooth, flat, level surface, with the 
laser facing straight ahead toward the opposing wall 
(0ºposition).
2.  Turn the laser ON to display a horizontal laser beam. Either:
a.  Move the Power/Transport Lock switch to the left to 
keep the pendulum locked and display the beams in 
manualmode (FigureA1).
b.  Move the Power/Transport Lock switch to the right 
to unlock the pendulum and display the beams in 
self-leveling mode (FigureA3).
3.  Press (FigureA4) once to display a horizontal laser beam, a 
second time to display a vertical beam, and a third time to 
display both the horizontal and verticalbeams.
4.  Check the laserbeams.
a.  If the laser is tilted so much that it cannot self-level  
(>4°), or the laser is not level in manual mode, the laser 
beams willflash.
b.  If the laser beams flash, the laser is not level (or 
plumb) and should NOT BE USED for determining or 
Horizontal Beam - Scan Direction
Checking the horizontal scan calibration of the laser requires 
two walls at least 30' (9m) apart. It is important to conduct a 
calibration check using a distance no shorter than the distance 
of the applications for which the tool will beused.
1.  Place back of the laser against a wall and facing straight 
ahead toward the oppsing wall (FigureD1).
2.  Move the Power/Transport Lock switch to the right 
(FigureA3) to turn the laser ON in self- leveling mode and 
display a horizontal and verticalbeams.
3.  Turn the laser 45º counter-clockwise so that the right-most 
end of the laser line is displayed on thewall.
4.  Mark a on the center of the beam on thewall.
5.  Turn the laser 90º clockwise so that the left-most end of the 
laser line is displayed near a (FigureD2).
6.  Mark d on the center of the beam on thewall.
7.  Measure the vertical distance between a and b .
8.  If your measurement is greater than the Allowable Distance 
Between a and b for the corresponding Distance Between 
Walls in the following table, the laser must be serviced at an 
authorized servicecenter.
Distance Between 
Walls
Allowable Distance Between 
a and b
30' (9 m) 15/32" (12 mm)
40' (12 m) 9/16" (14.4 mm)
50' (15 m) 23/32" (18 mm)
Checking Laser Accuracy
The laser tools are sealed and calibrated at the factory. It is 
recommended that you perform an accuracy check prior 
to using the laser for the first time (in case the laser was 
exposed to extreme temperatures) and then regularly to 
ensure the accuracy of your work. When performing any of 
the accuracy checks listed in this manual, follow these 
guidelines:
•  Use the largest area/distance possible, closest to the 
operating distance. The greater the area/ distance, the 
easier to measure the accuracy of thelaser.
•  Place the laser on a smooth, flat, stable surface that is 
level in bothdirections.
•  Mark the center of the laserbeam.
Battery Safety
 
WARNING: Batteries can explode, or leak, and can 
cause injury or fire. To reduce this risk:
•  Carefully follow all instructions and warnings on the 
battery label andpackage.
•  Always insert batteries correctly with regard to 
polarity (+ and –), as marked on the battery and 
theequipment.
•  Do not short batteryterminals.
•  Do not charge disposablebatteries.
•  Do not mix old and new batteries. Replace all batteries 
at the same time with new batteries of the same 
brand andtype.
•  Remove dead batteries immediately and dispose of 
per localcodes.
•  Do not dispose of batteries infire.
•  Keep batteries out of reach ofchildren.
•  Remove batteries when the device is not inuse.
Installing AA Batteries
Load new AA batteries in the STHT77498-1 or 
STHT77499-1laser.
1.  Turn the laser upsidedown.
2.  On the bottom of the laser, lift up the latch to open the 
battery compartment cover (FigureB1).
3.  Insert four new, high-quality, name brand AA batteries, 
making sure to position the - and + ends of each battery as 
noted inside the battery compartment (FigureB2).
4.  Push the battery compartment cover closed until it snaps in 
place (FigureB3).
When the laser is not in use, keep the Power/ Transport 
Lock switch in the center (OFF) position (FigureA2) to save 
batterypower.
marking level or plumb. Try repositioning the laser on a 
levelsurface.
5.  If ANY of the following statements are TRUE, continue with 
the instructions for Checking Laser Accuracy BEFORE 
USING THE LASER for aproject.
a.  This is the first time you are using the laser (in case 
the laser was exposed to extreme temperatures). 
b.  The laser has not been checked for accuracy in 
awhile.
c.  The laser may have been dropped.