5–27
Maintenance & Troubleshooting 5.0
Teledyne Analytical Instruments
A Business Unit of Teledyne Electronic Technologies
to 9.00 volts. When the zero fluid concentration (C
z
) is some
other value, proceed as follows:
Estimate the absorbance change (A
fs
) expected for full scale
changes in concentration. Then from the concentration of the
component of interest in the zero fluid (C
z
) and the full scale
meter reading (M
fs
) calculate the voltage setting at TP3 for the
zero fluid (V
z
).
log (V
z
) = - (A
fs
) C
z
9
M
fs
Example: If A
fs
= 1 unit
M
fs
= 10%
C
z
= 1%
Then:
log V
z
= - (1) (1)
9
10
log V
z
10
9
= 10
-.1
V
z
= (9) (0.79) = 7.15 volts
15. On the chopper stabilized log board place a DMM at TP1 (red).
Adjust the coarse ZERO control on the analysis unit to give an
output equal to (C
z
/C
fs
)(V
fs
). V
fs
equals the voltage output from
the chopper stabilized log board for a full scale deflection, which
equals 400 mV. For example, if:
C
z
= 1%
C
fs
= 10%
then the voltage output at TP1 will equal
(1/10)(400 mV) = 40 mV.
16. Set the span control on the control unit to 500.
17. Adjust the fine ZERO control on the control unit to give a meter
reading equal to C
z
.
18. Re-check the peak voltages on the switch driver and clamp
circuit at TP1 (violet). If the peaks have increased, it is probably
due to outgassing in the sample cell caused by improperly
locked-in sample, or by a leak in the system. Correct the problem
and repeat steps 10 thru 20.