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5.0 Maintenance & Troubleshooting
5. Using an oscilloscope, check the AC video signal at TP1 of
automatic gain control card (see dwg. B-14564). Maximize the
signal output with the adjustment, then tighten all screws in the
lens and lamp mounts
6. If an oscilloscope is not available, remove the filter wheel (see
Figure 5-1) and place a sheet of white paper in front of the
detector. Then adjust the lamp until the brightest, most uniform
spot of light is obtained. Avoid dark spots in the middle or sides.
The light shining on the detector may be viewed with a dental
mirror. Make certain that the detector is completely covered with
light.
NOTE: Do not touch the source lamp with fingers. The envelope must be
clean. If necessary, clean with mild detergent and water or solvent.
5.4
The filter position sensor is installed within the detector compartment;
the sensor is secured to its mount by a single 4-40 screw. To replace the
sensor, proceed as follows:
1. Remove the four screws securing the detector compartment
cover; remove the cover from compartment.
2. Remove mounting screw. Pull the sensor free from its mount.
3. Tag all wiring, then cut the wiring to the sensor.
4. Splice new wiring and cover with shrink tubing. The sensor
"tail" should be removed so that the space between the sensor
and the filter wheel is approximately 1/8 ".
5. After all wiring has been made and the spacing is correct, secure
filter position sensor with 4-40 screw.
5.5
The preamplifier circuit card is installed inside a preamplifier subassem-
bly which, in turn, is located within the detector compartment. To replace the
preamplifier circuit card, proceed as follows (see dwg. D-14665 and C-
14667):
1. Remove four screws securing detector compartment cover;
remove cover from compartment.
5–4
Teledyne Analytical Instruments
A Business Unit of Teledyne Electronic Technologies
Replacement of Filter Position Sensor
Replacement of Preamplifier Circuit Card
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Table of Contents
Troubleshooting
