Reaction Cell Temp; Preamp Board; Pmt Cooler - Teledyne 6400A Instruction Manual

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TAI Model 6400A SO

9.3.7 Reaction Cell Temp

The reaction cell temperature is controlled by the CPU. It operates by reading a thermistor
amplifier on the 01086 Status/Temp board. First LED from the front indicates the control power
on-off status which can be seen from the cover of the PSM through the slot.

9.3.8 Preamp Board

The Preamp Board is a multifunction board providing circuitry to support the following
functions.
1. Preamp, buffer amplifier, physical range control hardware for the PMT detector.
2. Precision voltage reference and voltage generation, and control for the PMT - HVPS inside
the sensor module.
3. Constant current generator and adjustment for the Optic Test LED.
4. Voltage generation and adjustment for Electric Test.
5. Thermistor amplifier and temperature control circuit for the PMT cooler.
The setup and adjustment of items 1-4 above is covered in the Factory Calibration procedure in
Section 9.1.6. Item 5 (see Section 9.3.9) is not adjustable.

9.3.9 PMT Cooler

The PMT cooler uses a Thermal Electric Cooler (TEC) supplied with DC current from the
switching power supply in the Power Supply Module. An overall view is shown in Figure 9-9.
The temperature is controlled by a temperature controller circuit located on the Preamp board.
Voltages applied to the cooler element vary from 0.1 to 12VDC. The input voltage from the
supply is 15VDC and LED indicates the presence of the voltage. Typical control voltage to the
FET is about 4.0 VDC when PMT temperature is at the 7
temperatures the 7
measured from the PCB mounted in the fan shroud. TP1 and TP4 (white) should measure
15VDC and the control voltage to the gate of the FET can be measured between pin 2 of the
white plug and TP4. Also under normal room temperature and at the 7
voltage between TP2 and TP3 will typically measure between 0.15V- 0.2V which translates to
about 1.5-2 Amp DC current flowing through the Thermal Electric Cooler (TEC). Following
procedures show how to replace the TEC assembly.
Analyzer Operator Manual, 02164, Rev. G
2
o
C set point should be maintained within 0.1
o
C setpoint. At normal room
o
C. These voltages can be
9-53
o
C PMT set point the

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