Teledyne T200, Operation Manual, Page: 273 / 425

Teledyne API
– T200 NO/NO
2
/NO
X
Analyzer Operation Manual Troubleshooting & Service
271
will be significant. In this case, a dryer for the supply air is recommended (dew point
should be –20° C or less).
The permeation tube of the internal span gas generator option is heated with a
proportional heater circuit and the temperature is maintained at 50°C ±1

C. Check the
front panel display or the IZS_TEMP signal voltage using the SIGNAL I/O function
under the DIAG Menu (Section 5.9.1). At 50° C, the temperature signal from the IZS
thermistor should be around 2500 mV.
12.7.17. TEMPERATURE SENSOR
12.7.17.1. BOX TEMPERATURE SENSOR
The box temperature sensor (thermistor) is mounted on the motherboard below the
bottom edge 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 usually read about 5° C higher than, ambient
(room) temperature because of the internal heating zones from the NO
2
converter,
reaction cell and other devices.

To check the box temperature functionality, we recommend checking the
BOX_TEMP
signal voltage using the
SIGNAL I/O
function under the
DIAG
Menu
(Section 12.1.3).

At about 30° C, the signal should be around 1500 mV.

To check the accuracy of the sensor, use a calibrated external thermometer /
temperature sensor to verify the accuracy of the box temperature by:

Placing it inside the chassis, next to the thermistor labeled
XT1
(above
connector J108) on the motherboard.

Compare its reading to the value of the test function
PMT TEMP
.
12.7.17.2. PMT TEMPERATURE SENSOR CONTROL
The temperature of the PMT should be low and constant. It is more important that this
temperature is maintained at a constant level than it is to be a specific temperature.
The PMT cooler uses a Peltier, thermo-electric cooler element supplied with 12 V DC
power 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 ±2

The actual temperature will be maintained to within 0.1° C around that set point.
To check the operation of the PMT temperature control system:
1. Turn off the analyzer and let its internal components cool / heat to ambient
temperature.
2. Turn on the analyzer.
3. Set the front panel to show the
PMT TEMP
test function (see Section 4.1.1).

The temperature should fall steadily to 6-10° C.

If the temperature fails to reach this point after 60 minutes, there is a problem in
the cooler circuit.

If the control circuit on the preamplifier board is faulty, a temperature of –1° C
will be reported.
06858E DCN7057