Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 230)

Troubleshooting & Repair Model 9110EH Instruction Manual
11.5.14. High Voltage Power Supply
The HVPS is located in the interior of the sensor module and is plugged into the PMT tube
(Section 10.3.2). It requires 2 voltage inputs. The first is +15 V, which powers the supply.
The second is the programming voltage which is generated on the preamplifier board.
Adjustment of the HVPS is covered in the factory calibration procedure in Section 11.6.5.
This power supply has 10 independent power supply steps, one to each pin of the PMT. The
following test procedure below allows you to test each step.
• Turn off the instrument.
• Remove the cover and disconnect the 2 connectors at the front of the NO
X
sensor
module.
• Remove the end cap from the sensor (4 screws).
• Remove the HVPS/PMT assembly from the cold block inside the sensor (2 plastic
screws).
• Re-connect the 7 pin connector to the sensor end cap, and power-up the instrument.
Scroll the front panel display to the HVPS test parameter. Divide the displayed
HVPS voltage by 10 and test the pairs of connector points as shown in the figure.
• Check the overall voltage (should be equal to the HVPS value displayed on the front
panel, for example 700 V) and the voltages between each pair of pins of the supply
(should be 1/10
th of the overall voltage, in this example 70 V):
• Turn off the instrument power, and reconnect the PMT, 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.
11.5.15. Pneumatic Sensor Assembly
The pressure/flow sensor circuit board, located behind the sensor assembly, can be checked
with a voltmeter using the following procedure, which assumes that the wiring is intact and
that the motherboard and the power supplies are operating properly. Refer to Figure 11-5
for trouble-shooting.
Measure the voltage across TP1 and TP2, it should be 10.0 ± 0.25 V. If not, the board is
faulty. Measure the voltage across the leads of capacitor C2. It should be 5.0 ± 0.25 V, if
not, the board may be faulty.
216 M9110EH Rev 0