Teledyne T200, Руководство по эксплуатации, Страница: 270 / 425

Troubleshooting & Service Teledyne API
– T200 NO/NO2/NOx Analyzer Operation Manual
268
1. Turn off the instrument power, and reconnect the PMT, and then reassemble the sensor.

If any faults are found in the test, you must obtain a new HVPS as there are no
user serviceable parts inside the supply.
12.7.14. PMT TEMPERATURE CONTROL PCA
The TEC control PCA is located on the sensor housing assembly, under the slanted
shroud, next to the cooling fins and directly above the cooling fan.
If the red LED located on the top edge of this assembly is not glowing the control circuit
is not receiving power. Check the analyzers power supply, the relay board‟s power
distribution circuitry and the wiring connecting them to the PMT temperature control
PCA.
TEC Control Test Points
Four test points are also located at the top of this assembly they are numbered left to
right start with the T1 point immediately to the right of the power status LED. These
test points provide information regarding the functioning of the control circuit.

To determine the current running through the control circuit, measure the voltage
between T1 and T2. Multiply that voltage by 10.

To determine the drive voltage being supplied by the control circuit to the TEC,
measure the voltage between T2 and T3.

If this voltage is zero, the TEC circuitry is most likely open.
Or,

If the voltage between T2 and T3 = 0 VDC and the voltage measured between
T1 and T2 = 0 VDC there is most likely an open circuit or failed op amp on
control PCA itself.

If the voltage between T2 and T3 = 0 VDC and the voltage measured between
T1 to T2 is some voltage other than 0 VDC, the TEC is most likely shorted.

T4 is tied directly to ground. To determine the absolute voltage on any one of the
other test points make a measurement between that test point and T4.
06858E DCN7057