Pneumatic Sensor Board; Figure 10-16: Pmt Preamp Block Diagram - Teledyne 100E Instruction Manual

Model 100E Instruction Manual
O Test Control
O Test
To
Motherboard
E Test Control
From CPU
PMT Temp Analog Signal
to Motherboard
PMT Temp
Sensor
TEC Control
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 6.7.6 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.

10.4.7. Pneumatic Sensor Board

The flow and pressure sensors of the M100E are located on a printed circuit assembly
just behind the PMT sensor. Refer to Section 11.5.15 on how to test this assembly. The
045150102 Rev XB1
From CPU
PMT Coarse
Gain Set
(Rotary
Switch)
LED
PMT HVPS
Drive Voltage
PMT Output
PCA

Figure 10-16: PMT Preamp Block Diagram

PMT Preamp PCA
O-Test
Generator
PMT Fine
Gain Set
(Rotary
Switch)
D-A
Converter
Amp to
Voltage
Converter/
Amplifier
MUX
E-Test
Generator
PMT
Temperature
Feedback
Circuit
PMT Output Signal
(PMT) to Motherboard
Theory Of Operation
Low Pass
Noise
Filter
PMT
Signal
Offset
183