Figure 6-18. Pmt Preamp Block Diagram - Teledyne T200 User Manual

Optical
Test
LED
High
Voltage
PMT
Power
Supply
X To
Motherboard
PMT Temp
Sensor
(Thermistor)
TEC Control
PCA
X PMT Temp Analog Signal
To Motherboard
X PMT Output Signal (
to Motherboard
The PMT preamplifier PCA also operates two different tests used to calibrate and check
the performance of the sensor module.
• The electrical test (Utilities>Diagnostics>OE 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 5.7.9.11 for instructions on performing this test.
The optical test (Utilities>Diagnostics>OE 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 5.7.9.11 for instructions on performing
this test.
083730200A DCN7962
Optical Test
Generator
Electric
Test
Generator
MUX
PMT HVPS
D à A
Converter
Drive Voltage
PMT
Temperature
Feedback
Circuit
PMT DET
)

Figure 6-18. PMT Preamp Block Diagram

Teledyne API T200 NO/NO
PMT Preamplifier PCA
Optical Test Control
Electric Test Control
HI Range Select
PMT Output
Physical Range
Gain
Select Circuitry
Adjustment
Amp à Volts
Low Pass
Converter
Noise
and
Amplifier
HVPS Fine
Gain
Adjustment
(Rotary)
HVPS Coarse
Gain
Adjustment
(Rotary)
/NO Analyzer with NumaView™ Software
2 x
X
from CPU
X
From CPU
X
From CPU
Filter
209