Teledyne 200E, Instruction Manual, Page: 231 / 302

Troubleshooting & Repair Model 200E Instruction Manual
11.5.17. O
3
Generator
The ozone generator can fail in two ways, electronically (printed circuit board) and
functionally (internal generator components). Assuming that air is supplied properly to the
generator, the generator should automatically turn on 30 minutes after the instrument is
powered up or if the instrument is still warm. See Section 0 for ozone generator functional-
ity. Accurate performance of the generator can only be determined with an ozone analyzer
connected to the outlet of the generator. However, if the generator appears to be working
properly but the sensitivity or calibration of the instrument is reduced, suspect a leak in the
ozone generator supply air.
A leak in the dryer or between the dryer and the generator can cause moist, ambient air to
leak into the air stream, which significantly reduces the ozone output. The generator will
produce only about half of the nominal O
3
concentration when run with moist, ambient air
instead of dried air. In addition, moist supply air will produce large amounts of nitric acid in
the generator, which can cause analyzer components downstream of the generator to
deteriorate and/or causes significant deposit of nitrate deposits on the reaction cell window,
reducing sensitivity and causing performance drift. Carry out a leak check as described
earlier in this chapter.
11.5.18. IZS Option
The zero/span valves and IZS options need to be enabled in the software (contact the
factory on how to do this). See Figure 3-12 for a flow diagram with zero/span valve or IZS
option and Figure 3-2 to locate these options in the rear left corner of the instrument.
• Check for the physical presence of the valves or the IZS option.
• Check front panel for correct software configuration. When the instrument is in
SAMPLE mode, the front panel display should show CALS and CALZ buttons in the
second line of the display. The presence of the buttons indicates that the option has
been enabled in software. In addition, the IZS option is enabled if the TEST functions
show a parameter named IZS TEMP.
The semi-permeable PTFE membrane of the permeation tube is severely affected by
humidity. Variations in humidity between day and night are usually enough to yield very
variable output results. If the instrument is installed in an air-conditioned shelter, the air is
usually dry enough to produce good results. If the instrument is installed in an environment
with variable or high humidity, variations in the permeation tube output will be significant.
In this case, a dryer for the supply air is recommended (dew point should be –20° C or
less).
The IZS option is heated with a proportional heater circuit and the temperature is
maintained at 50° C ±1
° . Check the front panel display or the IZS_TEMP signal voltage
using the SIGNAL I/O function under the DIAG Menu (Section 11.1.3). At 50° C, the
temperature signal from the IZS thermistor should be around 2500 mV.
11.5.19. Box Temperature
The box temperature sensor (thermistor) is mounted on the motherboard below the bottom
edge of the CPU board when looking at it from the front. It cannot be disconnected to check
its resistance. Box temperature will vary with, but will usually read about 5° C higher than,
216 044100102 Rev A