Auto Range Analog Meter (220-0216) Operation Faxback Doc. # 9676 METER READING Keep the tester on a flat, non-metallic surface for the most accurate readings. When using the manual range selection, select a setting that gives a reading in the upper 1/3 or 1/2 of the meter scale. When you read the scale, look at it from the point where the pointer and its reflection in the mirror come together. Read the scale that is appropriate to the function you select-green for resistance, black for voltage and current and red for decibels. To read the scale, use the appropriate markings based on the selected range (as indicated by the lighted RANGE indicators). Use This For These Ranges: For This Multiple Reading Scale Range: By: 3 300 mV, 3V, 300V x 10K 10,000 12 12V x 1K 1,000 60 60V x 0.1K 100 1000 1000V x 10 10 x 1 1 ZERO ADJUSTMENT If the pointer does not normally rest exactly over the zero at the left side of the V, A scale, adjust the plastic zero adjust screw in the center of the tester face to bring the pointer to zero. USING THE TEST LEADS Use only the same type of test leads as those supplied with your tester. These test leads are rated for 1200 volts. Replacement test leads (Cat. No. 278-704) are available at your local Radio Shack store. Caution: Although these test leads are rated for 1200 volts, the maximum rating of the tester is 1000V AC/DC. Do not attempt to measure any voltage greater than 1000V AC/DC. Connect the black test lead to the -com jack. Connect the red lead to: The +V-Ohms jack for making all AC and DC voltage and all resistance measurements, including continuity The +mA jack for current measurements up to 300 mA The +3A jack for current measurements from 300 mA to 3A If you connect to a circuit using the wrong polarity, the negative indicator turns on and you still get a valid measurement. Warning: Never allow your fingers to touch the bare metal portion of the test leads (or circuit points) during measurements. Caution: Always disconnect the test leads when you have finished using the tester. RANGE SELECTION You can select either manual or automatic range selection with your tester. In the automatic range mode, the tester automatically selects the range appropriate to the measurement you are making. Automatic Range Selection Press AUTO so the button is in to select automatic ranging. When you select automatic ranging for DCV or ACV measurements, the meter first sets the range to 3V. The meter automatically shifts to a higher range if required by the input voltage. When you select automatic ranging for resistance measurements, the meter first sets the range to x10k (200 MOhm). The meter automatically shifts to a lower range if required by the input resistance. The indicators below the meter scale show the selected range. Manual Range Selection Press AUTO so the button is out to select manual ranging. Then press the RANGE UP and DOWN buttons to light the indicator for the range you want. If you do not know the range to be measured, always start with the highest range. VOLTAGE MEASUREMENTS Warning: Use extreme care when making high-voltage measurements. Do not touch the terminal or test lead tips. 1. Plug the black test lead into the-COM jack. 2. Plug the red test lead into the +V-Ohms jack. 3. Set ON/OFF to ON. 4. Set the function switch to V~ or V____ for voltages higher than 300 mV. Set the function switch to mV~ or mV___ for AC or DC voltages below 300mV. Note: If you do not know the level of the voltage to be measured, start with the V___ or V~ position. 5. Select automatic or manual ranging (see "Range Selection"). 6. Connect the test lead tips to the circuit to be tested, with the red lead to the positive supply and the black lead to the negative supply for DC measurements. Note: If you connect the leads in reverse polarity for a DC measure- ment, the -DC indicator turns on and you get a valid measurement. 7. Read the voltage on the appropriate scale. Hint: When you use the tester to probe for a voltage in a high-voltage circuit, we recommend that you do not try to position both of the test leads at once. Instead, clamp one lead to the neutral or ground lead of the circuit, using Radio Shack insulated slip-on alligator clip (Cat. No. 270-354). Then probe for voltage with the other probe. This helps prevent you from accidentally touching a hot wire, since you need only concentrate on one test lead. Warning: Never clamp to a hot wire. If you do and then touch the other probe connected to the tester, you could receive an electrical shock. AC Voltage Riding On a DC Source Bias Measurements When measuring an AC voltage superimposed on a DC voltage source bias, set the function switch to AC~. Measuring 3-Phase AC Voltages We designed your meter to measure household AC voltage. It is intended for commercial or industrial use. Please note the following about 3-phase line-to-line voltages. Warnings: Because of the dangers inherent in measuring 3-phase circuits, do not use this meter for such applications. The actual voltage can be greater than the circuit's rated line-to- ground voltage. To determine the line-to-line voltage, multiply the rated line- to-ground voltage by 1.732 (the square root of 3). For example, if the rated line-to-ground voltage is 640 volts, the line-to-line voltage is: 640 x 1.732=1108 Volts This voltage exceeds the meter's rating and you should not connect the meter to this circuit. RESISTANCE MEASUREMENTS Warning: Do not apply voltage to the test leads when the function selector is in the (Ohms) position. Doing so causes the fuse to blow, and the tester stops working. Before taking any resistance measurements, disconnect power to the unit under test and discharge any capacitors. Remove any batteries from the unit under test and unplug any line cords. To make resistance measurements: 1. Plug the black test lead into the -COM jack and the red test lead into the +V-Ohms jack. 2. Set ON/OFF to ON. 3. Set the function selector to the Ohms (Ohms) position. 4. Select automatic or manual ranging (see "Range Selection"). 5. Connect the test lead tips across the circuit or part under test. Note: When measuring resistance, disconnect one side of the component under test so the remainder of the circuit does not interfere with the readings. 6. Read the resistance on the appropriate scale. When trying to identify the cathode and anode ends of a diode or the type of transistor (PNP or NON), the actual polarity of the tester's voltage is the opposite of the test lead colors. The red test lead is the negative source and the black test lead is positive. CONTINUITY CHECK Follow these steps to check for continuity in a wire or circuit. 1. Plug the black test lead into the -COM jack and the red test lead into the +V-Ohms jack. 2. Set ON/OFF to On. 3. Set the function selector to diamond. 4. Touch the test lead tips together to check the built-in buzzer. If the buzzer does not sound, check the fuse and the batteries. 5. Connect the test leads to the unit under test. The meter shows the measured resistance. If resistance is between 0 and 300 Ohms, the built-in buzzer sounds. Note: The buzzer's sound level decreases as the resistance increases. CURRENT MEASUREMENTS To measure current, you must break the circuit and connect the test leads in series with the circuit. Warning: Do not apply voltages to the test leads when the function selector is set to the mA/3A (CD or AC) position. Doing so blows the fuse, and the tester stops working. Note: The 3A range is not fuse-protected. To make current measurements: 1. Set ON/OFF to On. 2. Connect the red test lead to: +3A for current over 300 mA and under 3A. +mA for current of 300 mA or less. Note: If you do not know the level of the current to be measured, always start with the +3A jack. 3. Connect the black test lead to the -COM jack. 4. Set the function selector to mA/3A---for DC current, or mA/3A~ for current. 5. Remove power from the circuit under test and break the circuit at the appropriate point. 6. Connect the test leads in series with the circuit (black lead to negative and red lead to positive for DC measurement). Note: If you connect the test leads in reverse polarity for a DC measurement, the -DC indicator turns on and you get a valid measurement. 7. Apply power to the circuit under test. 8. Read the current on the appropriate scale. DECIBEL MEASUREMENTS Follow these steps to measure decibels. 1. Set ON/OFF to ON. 2. Plug the black test lead into the -COM jack and the red test into the +V-Ohms jack. 3. Set the function selector to V~. 4. Select either automatic or manual ranging (see "Range Selection"). 5. Connect the test lead tips to the circuit under test. 6. Read the red dB scale, adding the appropriate number of decibels to the dB scale as noted below: Range Add Number of dB 300 mV -20 3V 0 12V +12 60V +26 300V +40 1000V +52 Note: For the most accurate decibel readings, the circuit impedance must be 600Ohms. 0 dB=1 milliwatt dissipated in a 600 Ohm impedance (equivalent to 0.775 volts across 600 Ohms). (LB/all-02/23/95)