Line-Of-Sight; Maintenance - CST/BERGER SAL20N Instruction Manual

CALIBRATION
Your Automatic Level has been factory calibrated; however, you should occasionally check your
level for errors caused by shipment or rough handling.
Compensator lock button
Check the compensator for proper operation before use or anytime the operation of the instrument
is in question. Push and release the compensator lock button to shake the compensator. The
compensator should return to the exact horizontal position sighted before the lock button
was pressed.
Circular bubble vial
Center the vial bubble using the leveling screws, then rotate the instrument 180°. The bubble
should remain centered (Fig. 6). If the bubble moves out of center, the vial needs adjustment (Fig. 7).
Turn the leveling screws to bring the bubble halfway to center (Fig. 8). Using the Allen wrench, turn
the two vial adjustment screws to center the bubble (Fig. 9).
Repeat the above procedure until the bubble remains centered when the level is rotated 180°.

Line-Of-Sight

The line-of-sight needs to be horizontal within 3 mm of level to be accurate.
Set up and level the instrument on a tripod midway between two leveling rods set approximately
30m to 50m apart. Sight rods A and B; the height readings are a1 and b1 (Fig. 10). The value "H" is
equal to (a1 – b1). Move the instrument to within 6 feet (2m) of rod A and re-level. Again sight rods
A and B; these height readings are a2 and b2 (Fig. 11).
If a1 – b1 = a2 – b2 = H, the line-of-sight is horizontal. If not, the level should be adjusted as follows.
Because the instrument is set halfway between A and B, any error in the line-of-sight causes both
readings to be erroneous by the same amount. Error "e" cancels out, so the value a1 – b1 = H is
correct. Therefore, a2 – H = b3, the adjusting value.
To adjust, unscrew the eyepiece cover. Turn the adjusting screw with the adjusting pin (Fig. 12)
until the horizontal cross hair gives the reading b3, on rod B. Repeat the above Procedure until
{(a1-b1) – (a2-b2)} </= 3 mm.

MAINTENANCE

Care must be taken to maintain the accuracy of the instrument.
• After each use, the instrument should be wiped clean and kept in its carrying case.
• Remove dust from the lenses with a soft brush or a nonabrasive wipe. Never touch the
lenses with your fingers.
• Store the instrument in a dust-free area with low humidity.
• A bag of silica gel dryer is included with each instrument; if it has stopped working
effectively, bake it to remove moisture or replace with a new bag.
• Any damage to the instrument must be repaired by a
CST/berger Authorized Service Center.
PAL/SALN AutoLevel • 5