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1. Remove the thermal cover from the upper enclosure.
2. Loosen the ultem thumb screw and tilt the oven on its side to gain access to the
solenoids that are located on the underside of the ultem.
3. Loosen the screws holding the solenoid in place and remove the solenoid.
4. To replace the solenoid, reverse the procedure for removing them. Be sure to place
a small amount of silicone grease on the target device (pneumatic block, 4-way
stream block, etc.) where the solenoid is to be placed to ensure a tight seal.
4.4.7 Detector maintenance
When a TCD fails to perform normally it should be replaced. Signs that a TCD may be faulty
include, but are not limited to, the following:
• A chromatogram with a wandering or drifting baseline;
• A chromatogram with a noisy baseline;
• A chromatogram with a no peaks;
• No chromatogram.
A test for a faulty TCD involves measuring the resistance of each filament using a
voltmeter. A set of thermistors should give the same voltmeter reading; therefore, if a
thermistor reading is significantly different from the reading of its mate, the pair should be
replaced, otherwise the TCD bridge will be unbalanced, noisy and drifty.
Required tools for TCD maintenance
A flat-head screwdriver is required for removing and replacing TCDs.
TCD replacement parts
The following parts are required to replacing one TCD:
• Thermistor seal (P/N 6-5000-084)
• Thermistor set (P/N 6-1611-083)
Operation and maintenance
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Operation and maintenance
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