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Service
Microwave Leakage Measurement
The attenuator and cavity of the Discover SP-D Clinical are designed for reliable operation under severe laboratory
conditions. External radiation checks are performed on the system at several points in the manufacturing process,
ensuring that leakage from the finished instrument is only a fraction of that allowed by U.S. law (5 mW/cm2).
The attenuator is equipped with a safety interlock system to stop the generation of microwave energy when the attenuator
is opened or ajar. If the interlock system fails, a monitoring mechanism will blow the fuse(s) through which power is
supplied to the magnetron, rendering the microwave power system inoperable.
To verify that seals and interlocks are working properly, the Discover SP-D Clinical System should be tested periodically
for microwave leakage. Use the following procedure to measure microwave leakage:
1. Create a Dynamic method using 300 watts of power, 1 minute run time, 95 C temperature set-point, stirring
turned on at the “high” setting and PowerMAX on.
2. Place a round bottom flask containing 50mL of deionized water and a stir bar into the cavity.
3. Attach the attenuator to accept a 24/40 ground glass joint.
4. Load the created method and press START to begin the method.
5. Use a suitable RF field strength meter (microwave detector) such as the Holaday Model HI-1500 (available
from CEM Corporation, P/N 300500). Slowly move the RF probe around the attenuator perimeter and around the fan
grills to check for microwave leakage.
Note: CEM does not recommend use of meters available in electronics stores because they are prone to give erroneous
readings and lack the necessary sensitivity to properly test an instrument for microwave leakage.
The U.S. Government defines excessive microwave leakage as 5 mW/cm2. If the instrument shows excessive microwave
leakage, do not attempt further operation. Contact the CEM Corporation Service Department or the local CEM subsidiary
or distributor for further instructions.
Power Test
A power test can be performed to determine if the microwave is giving enough power input to heat the sample. A
thermometer (manual) or a Fiber Optic probe (Auto) can be used to test the power supply.
Manual Power Test
Items required for Manual Power test:
100 ml round bottom flask
100 ml water
Open vessel attenuator
Teflon vessel support
Stir bar appropriate for the round bottom flask
Thermometer
1. Log into the Discover as a user with Administrative privileges.
2. Press the DISCOVER key to display the “Load, Save, and Create Method” screen.
3. Press the “+/-” keys to highlight “Fixed Power.”
4. Press the ENTER key to select “Fixed Power” as the method control.
5. Press the Power hotkey.
6. Use the “+/-” keys to set the power to 300 watts.
7. Press the right ARROW key to change the time to 00:01:00.
8. Press the right ARROW key to change the temperature to 100°C.
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