Major Internal Components - Teledyne 7120 Operating Instructions Manual

5 Maintenance
Preamp
5.5

Major Internal Components

All internal components are accessed by unbolting and pulling open the
rack assembly, removing the front cover, as described earlier. The major
internal component locations are shown in Figure 5-3, the cell block is
illustrated in Figures 5-2/5-3, and the fuse receptacle is shown in Figure 5-1.
The 7100 contains the following major internal components:
• Customer Interface PCB (Power Supply on bottom surface)
• Preamp PCB (Contains Microprocessor)
• Front Panel PCB (Contains Displays)
5 digit LED meter
2 line, 20 character, alphanumeric, VFD display
See the drawings in the Drawings section in back of this manual
for details.
5-4
2 15 V Failures
3 Both Failed
Analog
0 OK
1 DAC A (0–1 V Concentration)
2 DAC B (0–1 V Range ID)
3 Both Failed
0 OK
1 Zero too high
2 Amplifier output doesn't match test input
3 Both Failed
>3 Call factory for information (204 may some
times appear even if call is ok. This might be
when reference and sample gases are not the
same)
Detector
0 OK
1 Failed (open filament, short to ground, no
power.)
2 Unbalance (deterioration of filaments, blocked
tube)
Teledyne Analytical Instruments
Model 7120