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5.0 Maintenance & Troubleshooting
19. Fill the sample cell with span fluid. Turn unit off, remove
chopper stabilized log board and place it on an extender board.
Turn the unit back on and adjust R16 on the chopper stabilized
log board to give a voltage at TP1 (red) equal to:
where V
which equals 400 mV.
Example: If C
Then:
Set the SPAN control (on the control module) to give a meter
reading of
20. Adjust the coarse ZERO control on the analysis unit until the
voltage at TP1 (red) is equal to:
21. Record the following data:
a. VDC on PLD, TP3 and TP4
b. VDC on chopper stabilized log operator, TP1 (red)
c. AC P-P on chopper stabilized log operator, TP2 (yellow)
d. AC P-P on automatic gain control PCB TP1 (violet)
e. Control unit meter readout.
22. An oscilloscope on TP2 (yellow) will display a 400 Hz square
wave. If this peak-to-peak voltage is less than 100 mV, decrease
the value of R13 (which will be 1K for most applications). If
the P-P voltage is greater than 0.4 volts, increase the value of
R13. If the voltage is still above 0.4 volts, the cell spacer must be
decreased, or other optical filters selected.
23. With a DMM on the log PCB TP1 (red) record VDC. If it is
below 0.2 volts, adjust R16; increase R17 if you run out of
adjustment with R16. If the voltage is higher than 0.4 volts,
5–28
Teledyne Analytical Instruments
A Business Unit of Teledyne Electronic Technologies
(C
- C
) V
s
z
fs
M
fs
is the voltage output from TP1 for full scale deflection,
fs
= 8%
s
C
= 1%
z
M
= 10%
fs
Voltage output at TP1 = 8-1 (400 mV)
C
- C
s
z
(C
/M
)V
s
fs
fs
10
= 280 mV
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Table of Contents
Troubleshooting
