Figure 12-20: Pmt Preamp Block Diagram - Teledyne t100 Operation Manual

Principles of Operation
O Test Control
From CPU
O Test
LED
To
Motherboard
E Test Control
From CPU
PMT Temp Analog Signal
to Motherboard
PMT Temp
Sensor
TEC Control
PCA
290
Generator
PMT
Coarse
Gain Set
(Rotary
PMT HVPS
Drive Voltage Converter
PMT Output
Generator
Temperature
Feedback
(PMT) to Motherboard

Figure 12-20: 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 (refer to Section 4.1.1).
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. Refer to Section 5.9.5 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,
Teledyne API - T100 UV Fluorescence SO
O-Test
PMT Fine
Gain Set
(Rotary
Switch)
D-A
Amp to
Voltage
Converter/
Amplifier
MUX
E-Test
PMT
Circuit
PMT Output Signal
PMT Preamp PCA
Low Pass
Noise
Filter
PMT
Signal
Offset
06807F DCN7335
Analyzer
2