Major Tech MT933 Cable Length Tester

1. Description

The Cable Length Meter is a hand-held testing device with the following measurement capabilities: resistance, temperature, and length. It can be used as mΩ meters to measure precise bonding resistances. Its primary function is to calculate the length of cable based upon its material, temperature, and cable gauge. Cable material type can be either uncoated copper or aluminum. There are 20 pre-programmed and eight programmable cable gauges. (There are no strands per cable specification for the eight programmable switch positions.)

2. Safety Instructions

WARNING: Observe the instructions given in this manual; improper use could damage the instrument or its components.

Double-insulated meter

• Do not connect this unit to live voltage.
• Do not expose this unit to rain or moisture.
• Do not use the unit if it is wet or damaged.
• Do not operate with the case open.
• Do not attempt to repair this unit; it contains no user-serviceable parts.
• Do not expose the unit to extremes in temperature or high humidity. Refer to "Specifications."
• Before opening the case, remove the test leads from the circuit and shut off the unit.
• Using this unit near equipment that generates electromagnetic interference can result in unstable or inaccurate readings.
• Inspect the test leads or accessory before use; they must be clean and dry, and the insulation must be in good condition.
• Use this unit for the manufacturer's intended purpose only, as described in this manual; any other use can impair the protection provided by the unit.
• Failure to observe these warnings could result in severe injury or death.

3. General Description

The instrument carries out the following measurements:

1. Twenty measurement gears in line with industry standards: 0.15, 0.25, 0.5, 0.75, 1, 1.5, 2.5, 4, 6, 10, 25, 35, 50, 70, 95, 120, 150, 185, 240mm².
2. Eight memory locations in user select mode.
3. mΩ resistance test mode.
4. Measures copper and aluminum cables.
5. Ambient temperature testing provides automatic compensation for measurements.

4. Meter Description

4.1. Instrument Description

The meter features the following components:

• 1 - LCD Display: Shows measurement readings, units, and status indicators.
• 2 - MEM Button: Used for saving data or confirmation in programming functions.
• 3 - CAL Button: Used for calibration and entering/exiting sample wire length setting mode.
• 4 - FT/M Button: Momentarily pressed to select length measurement units (feet or meters).
• 5 - HOLD Button: Freezes the current reading on the display.
• 6 - UP Button: Used to increase values during programming or selection.
• 7 - Cu/AI Button: Selects copper (Cu) or aluminum (Al) wire measurement, or toggles temperature units (°C/°F) when pressed and held.
• 8 - DOWN Button: Used to decrease values during programming or selection.
• 9 - Backlight Button: Turns the LCD backlight on or off.
• 10 - Rotary Selector Switch: Selects measurement modes and wire gauges (OFF, Ω, various Wire Gauge mm² settings).
• 11 - Test Lead Holders: Securely holds the test leads when not in use.
• 12 - Lanyard Hole: For attaching a lanyard.
• 13 - Battery Cover: Provides access to the battery compartment.
• 14 - Tilt Stand: Allows the meter to be propped up for easier viewing.
• 15 - Black Input Terminal: Connection point for black test leads.
• 16 - Red Input Terminal: Connection point for red test leads.
• 17 - NTC: (Negative Temperature Coefficient) sensor, likely for temperature measurement.

Diagram Description: The front of the MT933 meter is shown with its LCD display, control buttons (MEM, CAL, FT/M, HOLD, Cu/AI, UP/DOWN), and a rotary selector switch for modes and wire gauges. A side view reveals the battery compartment cover and a tilt stand. Input terminals (black and red) are also depicted, along with a note "Do Not Apply Voltage to Inputs".

4.2. Symbols and Annunciators

The LCD display uses various symbols:

• 1: Used to save data or for confirmation.
• 2: Indicates Temperature measurement.
• 3: Displays Celsius (°C) or Fahrenheit (°F) units.
• 4: Indicates Low Resistance measurement.
• 5: Indicates Copper (Cu) material.
• 6: Indicates Aluminum (Al) material.
• 7: Indicates calibration mode.
• 8: Measurement display digits.
• 9: Indicates milliohms (mΩ) for Resistance.
• 10: Indicates User Select Mode.
• 11: Displays length in kilo-feet (kft) or kilometers (km).
• 12: Data Hold indicator.
• 13: ERROR indicator.
• 14: Auto Power Off indicator.
• 15: Low battery indicator.
• 16: Negative reading display.
• 17: NTC (temperature sensor) indicator.

4.3. Accessories Provided

• Carrying Bag
• User Manual
• Copper Rod
• Kelvin Clips x 2

5. Description of Function Keys

• 5.1. Backlight Button: Press to turn the backlight on or off.
• 5.2. HOLD Button: Press to freeze the current reading on the display. Press again to exit Data Hold mode.
• 5.3. MEM Button: Used for user-selected programming functions. Press and hold to cancel the auto-shutdown function.
• 5.4. CAL Button: The meter must be calibrated each time it is turned ON. Used to enter/exit sample wire length setting mode.
• 5.5. FT/M Button: Press momentarily to select length measurement units. "ft" indicates feet, and "m" indicates meters.
• 5.6. Cu/AI Button: Press to select copper or aluminum wire measurement. Press and hold to select °C/°F for temperature.
• 5.7. Up/Down Button: Used during user-selected programming processes to adjust values.

6. Operating

WARNING: Do not connect the unit to live voltage.

6.1. Calibration Procedure

The meter should be calibrated each time it is turned ON before use.

1. Set the rotary switch from OFF to the 'Ω' Position.
2. Connect the red Kelvin clip lead to the red terminal on the meter and the black Kelvin clip lead to the black terminal.
3. Connect the two alligator clips to the supplied copper rod, ensuring the clips are as close together as possible for improved accuracy. Ensure the calibration bar and Kelvin clips jaws are clean.
4. Press the CAL Button. The display will alternately show "YES" and "NO" (flashing twice each time).
5. Press the MEM Button. If the display briefly shows "done" and returns to resistance measurement mode, calibration is successful.
6. If the display shows "FAIL", calibration has failed. Check connections and contacts. Pressing the CAL Button again will cancel calibration and return to resistance measurement mode.

6.2. Measuring Length of Wire

WARNING: Do not connect this unit to live voltage.

1. Set the rotary switch from OFF to the 'Ω' Position.
2. Calibrate the meter as described in "Calibration Procedure".
3. For best results, allow the meter and the wire to be measured to attain the same ambient temperature (typically about 30 minutes).
4. Strip the insulation back on each end of the wire to be measured. Ensure both ends are clean and the conductor is fully exposed. Use abrasive paper to remove any oxide layer if necessary.
5. Set the rotary switch to the appropriate Wire Gauge Position according to the wire's gauge (e.g., for 1 mm² wire, set to the "1" Position).
6. If measuring copper wire, press the Cu/Al Button until "Cu" appears on the display. For aluminum wire, press until "Al" appears.
7. Press the FT/M Button to select the desired unit (feet or meters).
8. Connect one alligator clip to one end of the wire and the other alligator clip to the other end.
9. The display will show the length of the wire.
10. When the measurement is finished, remove the alligator clips from the wire.

Typical Configuration: The meter is shown connected via alligator clips to a spool of wire, with the display indicating a length measurement.

6.3. User Select Mode

This mode allows users to save the resistance parameter of a custom wire for length measurements of similar wires (same gauge and conductor material). It also enables accurate measurement of standard gauge wires. Any metal wires (copper or aluminum) can be measured. The sample length for user wires must be between 4m and 100m (or 13.1ft and 320ft in FEET mode).

6.4. How to save the resistance of a user wire

Prepare a sample length of wire (4-100m or 13.1-320ft in FEET MODE) to be programmed into the meter. This allows the meter to correctly measure and store the resistance of this sample wire for future length measurements of the same kind of wire. Ensure the sample wire is not energized or live.

1. Set the rotary switch from OFF to the 'Ω' Position.
2. Calibrate the meter as described in "Calibration Procedure".
3. For best results, allow the meter and the sample wire to attain the same ambient temperature.
4. Remove insulation at both ends of the cable under test. Ensure conductors are clean, fully exposed, and insulation is removed to facilitate clamping. Use abrasive paper to clean exposed wire heads if needed.
5. Use the rotary knob to select the user-defined mode gear (1 through 8). The selected gear is displayed in the upper left corner of the screen. If a gear already has a cable parameter, it will display the parameter; otherwise, it may display "OL".
6. Press the FT/M Buttons to select feet or meters.
7. Press the CAL Button. The meter enters sample wire length setting mode. The display will alternately show "YES" and "NO", with "MEM" and "T-CAL" flashing twice.
8. Press the upper end of the Up/Down Button to increase or the lower end to decrease the reading in 0.1 increments until it equals the length of the sample wire.
9. Connect an alligator clip to one end of the sample wire and the other alligator clip to the other end.
10. Press the MEM Button once. If the display briefly shows "done" and returns to measurement mode, the setting was accepted.
11. If the display shows "FAIL" or "ERROR", the setting failed. Check connections and contacts. Press the CAL Button again to return to measurement mode.
12. When setting is finished, remove the alligator clips from the sample wire.

6.5. Measure the length of the cable in user-defined mode

1. Set the rotary switch from OFF to the 'Ω' Position.
2. Calibrate the meter as described in "Calibration Procedure".
3. For best results, allow the meter and the sample wire to attain the same ambient temperature.
4. Remove insulation at both ends of the cable under test, ensuring conductors are clean and exposed.
5. Using the rotary knob, select the appropriate user-defined gear measurement.
6. Press the FT/M Button to select feet or meters.
7. Connect the Kelvin Clips to the metal ends of the cable under test.
8. The cable length is read directly from the screen.
9. When the measurement is complete, disconnect the Kelvin Clips.

6.6. Clear memory locations in user select mode

1. Disconnect the Kelvin Clips from the cable under test.
2. Use the rotary knob to select the user-custom gear that needs to be cleared.
3. Press the CAL Button to display "YES". Press the MEM Button again; the meter will erase the stored data in the selected memory location and return to measurement mode with the location empty.
4. The symbol "MEM" indicates that pressing the MEM Button erases data; the symbol "CAL" indicates that pressing the CAL Button returns the meter to measurement mode.

6.7. Measuring Resistance

1. Set the rotary switch from OFF to the 'Ω' Position.
2. Calibrate the meter as described in "Calibration Procedure".
3. For best results, allow the meter and the sample wire to attain the same ambient temperature.
4. Remove insulation at both ends of the cable under test, ensuring conductors are clean and exposed.
5. Connect the red Kelvin clip lead to the red terminal and the black Kelvin clip lead to the black terminal on the meter.
6. The screen shows the impedance value read directly.

6.8. Measuring Temperature

1. The display shows the current temperature reading.
2. If the temperature is lower than -5°C (23°F), the display will show "-OL".
3. If the temperature is higher than 50°C (122°F), the display will show "OL".
4. Press and hold the Cu/Al Button to select °C/°F.

7. Maintenance

WARNING: Before opening the case, remove the test leads from the circuit and shut off the unit. This Meter is designed to provide years of dependable service if the following instructions are followed:

• Keep the meter dry. If it gets wet, wipe it off.
• Use and store the meter in normal temperatures; temperature extremes can shorten the life of electronic parts and distort or melt plastic parts.
• Handle the meter gently and carefully; dropping it can damage electronic parts or the case.
• Keep the meter clean; wipe the case occasionally with a damp cloth. Do not use chemicals, cleaning solvents, or detergents.
• Use only fresh batteries of the recommended size and type. Remove old or weak batteries to prevent leakage and damage.
• If the meter is to be stored for a long period, remove the batteries to prevent damage.

8. Battery Installation

WARNING: To avoid electric shock, disconnect the test leads from any source of voltage before removing the battery cover.

• Keep the meter dry. If it gets wet, wipe it off.
• Use and store the meter in normal temperatures; temperature extremes can shorten the life of electronic parts and distort or melt plastic parts.
• Handle the meter gently and carefully; dropping it can damage electronic parts or the case.
• Keep the meter clean; wipe the case occasionally with a damp cloth. Do not use chemicals, cleaning solvents, or detergents.
• Use only fresh batteries of the recommended size and type. Remove old or weak batteries to prevent leakage and damage.
• If the meter is to be stored for a long period, remove the batteries to prevent damage.

9. Specifications

9.1. Technical Specifications

9.2. General Specifications