Box Temperature; Pmt Temperature; Repair Procedures - Teledyne 100E Instruction Manual

TROUBLESHOOTING & REPAIR Model 100E Instruction Manual
high humidity, variations in the permeation tube output will be significant. In this case, a
dryer for the supply air is recommended (dew point should be-20° C or less).
The IZS option is heated with a proportional heater circuit and the temperature is
maintained at 50° C ±1°. Check the front panel display or the IZS_TEMP signal voltage
using the SIGNAL I/O function under the DIAG Menu (Section 11.1.3). At 50° C, the
temperature signal from the IZS thermistor should be around 2500 mV.

11.5.16. Box Temperature

The box temperature sensor (thermistor) is mounted on the motherboard at the bottom,
right corner of the CPU board when looking at it from the front. It cannot be
disconnected to check its resistance. Box temperature will vary with, but will always read
about 5° C higher than, ambient (room) temperature because of the internal heating
zones from the SO converter, sample chamber and other devices. To check the box
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temperature functionality, we recommend to check the BOX_TEMP signal voltage using
the SIGNAL I/O function under the DIAG Menu (Section 11.1.3). At about 30° C (5°
above typical room temperature), the signal should be around 1500 mV. We recommend
to use a certified or calibrated external thermometer / temperature sensor to verify the
accuracy of the box temperature.

11.5.17. PMT Temperature

PMT temperature should be low and constant. It is more important that this temperature
is maintained constant than it is to maintain it low. The PMT cooler uses a Peltier,
thermo-electric element powered by 12 VDC from the switching power supply PS2. The
temperature is controlled by a proportional temperature controller located on the
preamplifier board. Voltages applied to the cooler element vary from +/- 0.1 to +/- 12
VDC. The temperature set point (hard-wired into the preamplifier board) will vary by
about ±1° C due to component tolerances. The actual temperature will be maintained to
within 0.1° C around that set point. On power-up of the analyzer, the front panel enables
the user to watch that temperature drop from about ambient temperature down to its set
point of 6-8° C. If the temperature fails to drop after 20 minutes, there is a problem in
the cooler circuit. If the control circuit on the preamplifier board is faulty, a temperature
of -1° C is reported.

11.6. Repair Procedures

This section contains some procedures that may need to be performed when a major
component of the analyzer requires repair or replacement. Note that replacement
procedures that are discussed in detail in Chapter 9 (Maintenance) are not listed here.
Servicing of circuit components requires electrostatic discharge protection, i.e. ESD
grounding straps, mats and containers. Failure to use ESD protection when working with
electronic assemblies will void the instrument warranty.
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