HAMAR LASER STEALTH Series, General Training Manual

Page: 102 / 113

98
The Calibration Trimpot
If the error in the calibration checking procedure is between 5 and 15 percent, calibrate the readout to the
target as follows:
Figure 48 - Open R-307 Readout with trimpots exposed
1. Unscrew the screws on the back of the readout housing
Separate the top and bottom half of the readout to gain access to the Master (vertical) and Slave
(Horizontal) Input Trim Screws .
2. Set the Readout Scale Switch
Set the Readout Scale Switch to the .0001 in. scale (highest resolution).
The Calibration Trimpot is located on the side of the circuit board on the inside of the readout. The
Trimpots are actually small screws that can be manually turned with a small, flat-head screwdriver (see
Figure 48.
•
On the Model R-307 Readout, two of the four trimpot screws (the inside pair) have been glued into
position and should be left alone. If these screws have been tampered with or turned, return the
readout to the factory for service.
•
On the Model R-308 Readout, one of the two screws (lowest on the readout) has been glued into
position and should be left alone. If this screw has been tampered with or turned, return the readout to
the factory for service.
The readouts are very sensitive. A turn of the screw will be instantly displayed as a change in the numeric
information on the readout window. As you go through the procedural steps on the next pages, watch the
readout while adjusting the trimpot screw to the left or right. The numbers on the readout display will
change.
As with most analog electronic devices, the receiver must be tuned to the signal. Micrometer turns of
+.025 in. and -.025 in. may "read out" as 24.0 and -23.0 or 28.0 and -22.0. The readout is accurate when
the total of the readout numbers is within 5 percent of the .025 in. micrometer move.
To calculate: