Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 259)

Troubleshooting & Repair Model 9110TH NOx Analyzer
Teledyne Analytical Instruments 239
 Use the RS-232 test function to send “w” characters to the modem, terminal
or computer; See Section 6.11.10.
 Get your terminal, modem or computer to transmit data to the analyzer
(holding down the space bar is one way). The green LED on the rear panel
should flicker as the instrument is receiving data.
 Make sure that the communications software is functioning properly.
Further help with serial communications is available in a separate manual “RS-232
Manual”, TAI part number 013500000, available online at http://www.Teledyne-
api.com/manuals/.
7.5.13. PMT SENSOR
The photo multiplier tube detects the light emitted by the reaction of NO with ozone. It
has a gain of about 1: 500000 to 1:1000000. It is not possible to test the detector outside
of the instrument in the field. The best way to determine if the PMT is working properly
is by using the optical test (OTEST), which is described in Section 6.13.6.2. The basic
method to diagnose a PMT fault is to eliminate the other components using ETEST,
OTEST and specific tests for other sub-assemblies.
7.5.14. PMT PREAMPLIFIER BOARD
To check the correct operation of the preamplifier board, we suggest to carry out the
optical and electrical tests described in Sections 6.13.6.2 and 4.13.7.3. If the ETEST
fails, the preamplifier board may be faulty. Refer to Section 13 on hardware calibration
through the preamplifier board.
7.5.15. HIGH VOLTAGE POWER SUPPLY
The HVPS is located in the interior of the sensor module and is plugged into the PMT
tube (Section 8.5.2). 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 13. 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.