Teledyne 6200E - Sulfides Analyzer - Manual (Page 225)

Model 6200E Instruction Manual Theory Of Operation
M6200E Rev: A1 225
adjustments should only be performed when encountering problems with the software calibration
that cannot be rectified otherwise. See Section 11.6.3 for this hardware calibration.
To
Motherboard
PMT Preamp PCA
Low Pass
Noise
Filter
E Test Control
From CPU
MUX
Amp to
Voltage
Converter/
Amplifier
D-A
Converter
PMT Coarse
Gain Set
(Rotary
Switch)
PMT Fine
Gain Set
(Rotary
Switch)
PMT
Signal
Offset
E-Test
Generator
O-Test
Generator
O Test Control
From CPU
PMT Temp
Sensor
PMT
Temperature
Feedback
Circuit TEC Control
PCA
PMT Output
PMT HVPS
Drive Voltage
PMT Temp Analog Signal
to Motherboard
PMT Output Signal
(PMT) to Motherboard
O Test
LED
Figure 10-16: PMT Preamp Block Diagram
The PMT temperature control loop maintains the PMT temperature around 7° C and can be viewed
as test function PMT TEMP on the front panel.
The electrical test (ETEST) circuit generates a constant, electronic signal intended to simulate the
output of the PMT (after conversion from current to voltage). By bypassing the detector’s actual
signal, it is possible to test most of the signal handling and conditioning circuitry on the PMT
preamplifier board. See section 6.9.6 for instructions on performing this test.
The optical test (OTEST) feature causes an LED inside the PMT cold block to create a light signal
that can be measured with the PMT. If zero air is supplied to the analyzer, the entire
measurement capability of the sensor module can be tested including the PMT and the current to
voltage conversion circuit on the PMT preamplifier board. See section 6.9.5 for instructions on
performing this test.