Thermal Stimulator

Thermal Stimulator: Out of calibration

Possible Cause 1: A "black dot label" (emissivity sticker) is not being used during Thermal Stimulator calibration verification.

What to do: Locate the emissivity sticker, which looks like a black dot, and repeat the calibration verification procedure (described in the Service Bulletin CASE4-B08, or on pages 6.4 and 6.4-b of the Hardware User's Guide).

Possible Cause 2: Thermal Stimulator is not correctly connected to Main Unit.

What to do: Verify that the blue constantan-copper plug (Thermal Stimulator connector B) and the round connector (Thermal Stimulator connector A) are correctly installed. Refer to chapter 4 of the CASE IV System Hardware User's Guide for set-up instructions. Verify that the hoses are attached to the Thermal Reservoir.

Possible Cause 3: Batteries in the voltmeter or infrared thermometer are low.

What to do: Check the batteries in the voltmeter and the infrared thermometer. Refer to the "Thermal Stimulator Calibration Check" section in chapter 6 of the CASE IV System Hardware User's Guide for battery specifications.

Note: The infrared thermometer has a high current draw on the battery. If left on for an extended period the battery will be below specifications and will need to be replaced.

Possible Cause 4: Ambient temperature of testing room is out of the acceptable range.

What to do: Verify that the temperature of the testing room is not under 24°C/75.2°F or over 26°C/78.8°F. If the ambient temperature is out of range, adjust the room temperature. It is important to keep the room at a constant temperature at all times. Allow the equipment to stabilize after each ambient temperature change.

Possible Cause 5: Temperature of the water in the Thermal Reservoir is out of the acceptable range.

What to do: Verify the temperature of the water in the reservoir is not under 24°C/75.2°F or over 26°C/78.8°F. Heat up or cool down the water accordingly.

Note: After changing the temperature of the reservoir, you must allow a minimum of 15 minutes or more to allow the water in the system to circulate and be uniform throughout.

Possible Cause 6: Water is not flowing through the Thermal Stimulator system.

What to do: Take the top off the Thermal Reservoir and lift the hose. Verify that water is flowing through the hose and that the water level is between the fill lines. If the water is too high or too low, adjust accordingly. If water is not flowing through the hose, look into the following:

1. Check that the Thermal Reservoir is plugged into the plug strip (or isolation transformer).

2. Is the water in the tank old or dirty? If so, the water in the reservoir should be replaced. (Replace the water at least every 90 days.)

3. With the Thermal Stimulator attached, blow out the hose with compressed air at low pressure (10 to 20 pounds per square inch, or psi). This may clear the hose of any blockages that restrict water flow.

Note: The use of a bactericide in the water is recommended to help control the bacterial/algae growth, which can adversely affect the performance of the system.

Possible Cause 7: Temperature of Thermal Stimulator hardware is outside of the acceptable range.

What to do: Check the temperature of the Thermal Stimulator's ceramic plate by doing the following:

1. With the CASE IV System on, exit from any calibration verification procedures or tests.

2. Ensure that the system has been on for at least 15 minutes.

3. Place the Thermal Stimulator and the infrared thermometer in the Thermal Calibration Fixture, as if performing calibration verification.

4. Allow the temperature on the infrared thermometer to stabilize, and verify the temperature is not under 24°C/68°F or over 26°C/72°F. If not within range, see possible cause 4.

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Possible Cause 8: Calibration of the voltmeter or infrared thermometer.

What to do: Check the calibration sticker on these items to verify that the calibration periods have not expired.

Note: It is recommended that these items be calibrated to NIST standards at least once per year.

Possible Cause 9: The voltmeter or infrared thermometer is out of calibration, even though date on the sticker indicates the calibration period has not expired.

What to do: Point the infrared thermometer at something that is exactly 0°C. For example, put cold water and ice cubes in a dark-colored container (such as a black ceramic coffee cup). Point the infrared thermometer at the water, and verify that the reading on the voltmeter is 0°C.

Possible Cause 10: Temperature readings are being taken at the wrong time.

What to do: Are you examining the temperature reading after selecting "Set Aluminum Block to 30 Degrees Celsius"? This routine warms up the stimulator, and readings are not supposed to be taken during this step. Check the calibration at 30 degrees using the "Thermal 30 Degree Test." Review the calibration verification procedure in the Hardware User's Guide.

Possible Cause 11: The stimulator and infrared thermometer are not properly positioned in the Thermal Calibration Fixture.

What to do: Make sure white ceramic face of the Thermal Stimulator is directed inward toward the square hole in the fixture, and make sure both the Thermal Stimulator and the infrared thermometer's probe are fully seated as far as they will go.

Possible Cause 12: All the hardware is too cold.

What to do: This situation is typical if the unit has just been set up after being stored in a cool truck, airplane, or storage room. Set up the unit and leave it on for 24 hours to bring all the components and electrical parts up to operating temperature.

Possible Cause 13: Poor connection on constantan-copper plug.

What to do: Unplug and reconnect the blue constantan-copper plug (Thermal Stimulator connector B) several times. Using an eraser, remove any oxidation that may have occurred.

Possible Cause 14: The Thermal Stimulator may be defective.

What to do: Contact your help desk for repair instructions.

Thermal Stimulator: Operation seems too hot or cold

Possible Cause 1: Unit feels too hot or cold but is operating normally, but patient thinks it is too hot or too cold.

What to do: Reverify the calibration and reinstruct the patient if the unit is found to be within calibration.

Possible Cause 2: During calibration, the temperature is too low or too high.

What to do: See the "Thermal Stimulator: Out of Calibration" section of this Troubleshooting Guide.

Thermal Stimulator: Patient reports that the Thermal Stimulator feels cool all the time, or hot all the time

Possible Cause: The operator typed in a JND level instead of the baseline skin temperature.

What to do: If the operator types in a JND level such as "13" at the beginning of thermal testing when he should have typed in the baseline skin temperature of 30 degrees C., then the computer's baseline skin temperature will be incorrect (it will go down to 13 degrees C. and stay there for the duration of the test).

Thermal calibration verification doesn't work

Possible Cause: The Thermal Stimulator was placed into the fixture backwards (aluminum side in).

What to do: Make sure the ceramic side faces into the fixture.

Thermal calibration verification works at 30 degrees C., but not at 20 or 40 degrees

Possible Cause: The temperature is released to 30 degrees C. whenever the blue screen appears.

What to do: Take your reading during the black screen, while the screen says "Calibration in Progress."

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Vibration Stimulator

Vibration Stimulator: Out of calibration

Possible Cause 1: The distance to the calibration chart is incorrect.

What to do: Verify that the distance from the prism on the Vibration Stimulator to the location of the vibration calibration chart is exactly as it should be. Use either 2, 4, 6, or 8 meters. Review the calibration verification procedure in the Hardware User's Guide. (The 4- or 6-meter tests are the best distances to use.)

Possible Cause 2: The Main Unit is not providing the correct output voltage.

What to do: To verify the output of the Main Unit to the Vibration Stimulator, perform the following:

1. Exit the CASE IV software and return to DOS.

2. Unplug the Vibration Stimulator from the back of the Main Unit.

3. Plug the two banana plugs, colored red and black, of the Vibration Calibration Cable into the volt meter. Note the color-coded receptacles.

4. Set the volt meter to read AC voltage.

5. Connect the other end of the Vibration Calibration Cable into the back of the Main Unit, the jack labeled "Vibration Stimulator."

6. On the keyboard of the computer, type "vibrmo -cal 575" at the DOS prompt. Note: Consult your computer's operating guide for instructions on entering or executing DOS commands or programs for the command line.

7. Verify the reading on the DMM is between 4.9vac and 5.1vac.

8. If verification shows the voltage not within specifications, contact WR Medical Electronics Co. for repair instructions.

Possible Cause 3: The arm on the Vibration Stimulator is loose.

What to do: It is imperative that this mechanism (called the spring mechanism) be in an exact location for the calibration and operation to be successful and consistent. After becoming loose, the unit is no longer in calibration. Contact your help desk for further instructions.

Vibration Stimulator: Appears not to vibrate

Possible Cause: Vibration Stimulator is not correctly connected to Main Unit.

What to do: Verify that the connector is correctly installed. Refer to chapter 4 of the CASE IV System Hardware User's Guide for set-up instructions. If unresolved, see the "Vibration Simulator: Out of Calibration" procedure.

Vibration Stimulator: Laser beam is not working

Possible Cause: Laser fixture is not correctly connected to Main Unit.

What to do: Verify that the connector is correctly installed. Refer to chapter 4 of the CASE IV System Hardware User's Guide for set-up instructions. If unresolved, contact your help desk.

Vibration Stimulator: Laser beam is fuzzy

Possible Cause 1: Foreign substance may be on prism.

What to do: Check for the presence of any foreign substance on the Vibration Stimulator prism or on the lens of the Vibration Laser Calibration Fixture. Gently clean these parts, taking care not to damage either unit. Use a can of pressurized air to blow dust off the parts.

Possible Cause 2: Laser is out of focus.

What to do: Use the supplied focusing ring, which should be attached to the laser stand, to adjust the focus of the beam while the fixture is aligned according to the procedure in chapter 6 of the CASE IV System Hardware User's Guide.

Caution: Do not stare into the laser beam.

Vibration Stimulator: Laser beam is dim

Possible Cause 1: Ambient lighting in the room excessive.

What to do: During the calibration routine, dim the room lights to maximize the visibility of the beam.

Possible Cause 2: Improper alignment of units during calibration.

What to do: The Vibration Stimulator and the Vibration Laser Calibration Fixture must be properly aligned for the laser beam to shine through the Vibration Stimulator's prism. Make sure that the bases of each device touch, and the white stub on the Vibration Laser Calibration Fixture is positioned on the midline of the Vibration Stimulator. Look at the prism to make the final left-right adjustment of the beam.

Caution: Do not stare into the laser beam.

Vibration Stimulator: Won't stay up

Possible Cause 1: The friction washer has become loose.

What to do: The washer can be tightened up by any qualified biomedical equipment repair-person or by competent, mechanically inclined individuals. Contact your help desk for a copy of the procedure for tightening the friction washers.