Subsystem Checkout; Simple Vacuum Leak And Pump Check; Detailed Pressure Leak Check - Teledyne 200E Instruction Manual

Troubleshooting & Repair
Check the power supply to the valve (12 V to the valve should turn on and off when
measured with a voltmeter).
Note that it takes only a small leak across the ports of the valve to show excessive
auto-zero values when supplying high concentrations of span gas.
• Another reason for high (although not necessarily out-of-range) values for AutoZero
could be the ozone air filter cartridge, if its contents has been exhausted and needs
to be replaced. This filter cartridge (Figure 3-2) filters chemicals that can cause
chemiluminescence and, if saturated, these chemicals can break through to the
reaction cell, causing an erroneously high AutoZero value (background noise).
• A dirty reaction cell can cause high AutoZero values. Clean the reaction cell
according to Section 9.3.9.
• Finally, a high HVPS voltage value may cause excess background noise and a high
AZero value. The HVPS value changes from analyzer to analyzer and could show
nominal values between 450 and 800 V. Check the low-level hardware calibration of
the preamplifier board and, if necessary, recalibrate exactly as described in Section
11.6.5 in order to minimize the HVPS.

11.5. Subsystem Checkout

The preceding sections of this manual discussed a variety of methods for identifying
possible sources of failures or performance problems within the analyzer. In most cases this
included a list of possible causes and, in some cases, quick solutions or at least a pointer to
the appropriate sections describing them. This section describes how to determine if a
certain component or subsystem is actually the cause of the problem being investigated.

11.5.1. Simple Vacuum Leak and Pump Check

Leaks are the most common cause of analyzer malfunction; This section presents a simple
leak check, whereas Section 11.5.2 details a more thorough procedure. The method
described here is easy, fast and detects, but does not locate, most leaks. It also verifies the
sample pump condition.
• Turn the analyzer ON, and allow at least 30 minutes for flows to stabilize.
• Cap the sample inlet port (cap must be wrench-tight).
• After several minutes, when the pressures have stabilized, note the SAMP (sample
pressure) and the RCEL (vacuum pressure) readings.
• If both readings are equal to within 10% and less than 10 in-Hg-A, the instrument is
free of large leaks. It is still possible that the instrument has minor leaks.
• If both readings are < 10 in-Hg-A, the pump is in good condition. A new pump will
create a pressure reading of about 4 in-Hg-A (at sea level).

11.5.2. Detailed Pressure Leak Check

If a leak cannot be located by the above procedure, obtain a leak checker similar to T-API
part number 01960, which contains a small pump, shut-off valve, and pressure gauge to
create both over-pressure and vacuum. Alternatively, a tank of pressurized gas, with the
two stage regulator adjusted to ≤ 15 psi, a shutoff valve and pressure gauge may be used.
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Model 200E Instruction Manual
044100102 Rev A