Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 229)

Model 9110EH Instruction Manual Troubleshooting & Repair
the green LED should also illuminate. If not, set the DCE/DTE switch to the other
position. See also Section 6.9.5.
• Note that some laptops do not enable their RS-232 port when in power-saving
mode. In this case, connect the laptop and start either APICOM or a Hyperterminal
window and start communicating with the analyzer. This will enable the serial port
on the laptop and the green LED should illuminate. You may have to switch back and
forth while communicating to get the right setting.
11.5.11.2. Modem or Terminal Operation
These are the general steps for troubleshooting problems with a modem connected to a
TAI
analyzer.
• Check cables for proper connection to the modem, terminal or computer.
• Check the correct position of the DTE/DCE as described in Section 6.9.5.
• Check the correct setup command (Section 6.11.3).
• Verify that the Ready to Send (RTS) signal is at logic high. The M9110EH sets pin 7
(RTS) to greater than 3 volts to enable modem transmission.
• Make sure the baud rate, word length, and stop bit settings between modem and
analyzer match, see Section 6.9.7.
• Use the RS-232 test function to send “w” characters to the modem, terminal or
computer; See Section 6.9.8.
• 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”.
11.5.12. PMT Sensor
The photo multiplier tube 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 best way to determine if the PMT is working properly is by using
the optical test (OTEST), which is described in Section 6.7.5. The basic method to diagnose
a PMT fault is to eliminate the other components using ETEST, OTEST and specific tests for
other sub-assemblies.
11.5.13. 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 6.7.5 and 6.7.6. If the ETEST fails, the
preamplifier board may be faulty. Refer to Section 11.6.5 on hardware calibration through
the preamplifier board.
M9110EH Rev 0 215