Teledyne T200, Operation Manual, Page: 267 / 425

Teledyne API
– T200 NO/NO
2
/NO
X
Analyzer Operation Manual Troubleshooting & Service
265
12.7.12. PHOTOMULTIPLIER TUBE (PMT) SENSOR MODULE
The PMT detects the light emitted by the reaction of NO with ozone. It has a gain of
about 500000 to 1000000. It is not possible to test the detector outside of the instrument
in the field. The basic method to diagnose a PMT fault is to eliminate the other
components using
ETEST , OTEST and specific tests for other sub-assemblies.
12.7.12.1. OPTIC TEST
The optic test function tests the response of the PMT sensor by turning on an LED
located in the cooling block of the PMT (see Figure 12-9). The analyzer uses the light
emitted from the LED to test its photo-electronic subsystem, including the PMT and the
current to voltage converter on the pre-amplifier board.

To ensure that the analyzer measures only the light coming from the LED, the
analyzer should be supplied with zero air.

The optic test should produce a PMT signal of about 2000±1000 mV.
To activate the optics test, press:
Concentration display
continuously cycles
through all gasses.
SAMPLE RANGE=500.0 PPB NOX= XXXX
<TST TST>
CAL
SETUP
SETUP X.X
SECONDARY SETUP MENU
COMM VARS
DIAG
EXIT
SETUP X.X
PRIMARY SETUP MENU
CFG DAS RNGE PASS CLK
MORE
EXIT
DIAG
SIGNAL I/O
PREV
NEXT
ENTR EXIT
SETUP X.X
ENTER PASSWORD
8 1 8 ENTR
EXIT
Continue pressing
NEXT
until ...
DIAG
OPTIC TEST
PREV NEXT
ENTR
EXIT
Continue pressing
<TST
or
TST>
until ...
SAMPLE PMT=2750 MV NOX= XXXX
<TST TST> CAL
SETUP
SAMPLE PMT=2750 MV NOX= XXXX
<TST TST> CAL
EXIT
While the OTEST is
active PMT should =
2000 mv ± 1000mv
Note
This is a coarse test for functionality and not an accurate calibration tool. The
resulting PMT signal can vary significantly over time and also changes with low-
level calibration.
06858E DCN7057