Pmt Temperature Control Pca; High Voltage Power Supply - Teledyne T100 Instruction Manual

Teledyne ML - T100 UV Fluorescence SO2 Analyzer

10.6.13. PMT TEMPERATURE CONTROL PCA

10.6.13.1. TEC CONTROL TEST POINTS

10.6.14. HIGH VOLTAGE POWER SUPPLY

The TEC control printed circuit assembly 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 analyzer's power supply, the relay board's power distribution circuitry and
the wiring connecting them to the PMT temperature control PCA.
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.
 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.
The HVPS is located in the interior of the sensor module and is plugged into the PMT
tube (refer to Figure 9-17). It requires 2 voltage inputs. The first is +15 which powers the
supply. The second is the programming voltage which is generated on the Preamp Board.
This power supply is unlike a traditional PMT HVPS. It is like having 10 independent
power supplies, one to each pin of the PMT. The test procedure below allows you to test
each supply.
1. Check the HVPS test function via the front panel Turn off the instrument and record
the reading level. Adjustment of the HVPS output level is covered in the hardware
calibration procedure in Section 10.7.2.8.
2. Turn off the instrument.
3. Remove the cover and disconnect the 2 connectors at the front of the PMT housing.
4. Remove the end plate from the PMT housing.
5. Remove the HVPS/PMT assembly from the cold block inside the sensor. Un-plug the
PMT.
6. Re-connect the 7 pin connector to the Sensor end cap, and power-up the instrument.
06807A(DCNxxxx)
Troubleshooting & Repair
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