GB GMT-318 User Manual [en, es, fr]

GMT-318 6-09 manual.qxp 6/8/09 2:03 PM Page 1

	Analog Multimeter
	Owners Manual
	Multímetro análoga
	Manual del propietario
GMT-318	Multimètre analogue
	Manuel d’utilisation

•Read this owners manual thoroughly before use and save.

•Lea completamente este manual del propietario antes del uso y consérvelo como referencia.

•Avant de se servir du multimetre, lire attentivement le present manuel d’utilisation, et le conserver.

GMT-318 6-09 manual.qxp 6/8/09 2:03 PM Page 2

Contents

1.Introduction

1.1Meter Functions

2.Specifications

2.1For Your Safety

3.Operating Suggestions

3.1Preliminary Adjustments

3.2Internal Battery Condition

4.DC Voltage Measurement

5.DC Milliamp Measurement

6.AC Voltage Measurement

6.1Wall Receptacles

7.Resistance/Continuity Measurement

7.1Extension Cords

7.2Fuses

7.3Switches

8.Decibel Measurement (Transistor Gain)

9.Household Batteries

10.Battery and Fuse Replacement

11.Warranty

12.Disposal

1. Introduction

The GMT-318 is an Analog Multimeter capable of measuring 6 functions on 14 ranges. A mirror scale is provided to reduce the possibility of parallax errors. Small lightweight and rugged construction. This meter was designed for the homeowner, hobbyist and professional needing to make electrical and electronic equipment measurements.

	1.1 Meter Functions	Analog
	Needle
		Scale
	Mirror
		Battery/
		Fuse
		Cover
		Mechanical
		Zero
		Adjust
		Screw
		Function/
		Range
		Selector
	Zero	Switch
	Ohms
	Adjust
	ment
	Input Jacks
	Figure 1

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2. Specifications

Ranges:	14 measuring ranges
DC Voltage:	10-50-250-500 Volts
AC Voltage:	10-50-250-500 Volts
DC Current (Milliamperes):	250mA
Resistance (Ohms):	Rx1, Rx10, Rx100
Decibels:	-20dB to +56dB on AC voltage ranges
Battery:	1.5, 9V
Accuracy:	DC voltage, mA = ±4% full scale of range
	AC voltage = ±5% full scale of range
	Resistance = ±4° arc of scale length
Sensitivity:	2000 ohms per volt DC and AC
Function/Range Switch:	6 functions
	15 positions
	14 measuring ranges
Zero Ohms Adjustment Dial:	Located on the left side of the housing;
	adjustment dial is used to zero the needle
	indicator on the ohms scale while
	shorting the test leads together.
Mechanical Zero
Adjustment Screw:	Located directly below the center of the
	meter scale; adjust needle indicator to
	read zero at the left side of the scale
	before taking any measurement.
Mirrored Scale Plate:	The mirror on the scale plate is used to
	line up the needle with its reflection to
	improve the reading accuracy by
	preventing parallax error.
Recessed Input Jacks:	Negative (-) input jack for black test lead,
	positive (+) input jack for red test lead.
Fuse Type:	F500mA, 250V, GB GF-0306
Power Source:	One 1.5V AA size (non-rechargeable) battery
Test Lead Type:	ETL, cETL, CE, CATII 500V 1A
Size (L X W X H):	approx 109mm X 70mm X 33mm
Weight:	approx 140g (including battery)
Agency Approvals:	ETL cETL, CE, CATII 500V
Operating Temperature:	64F-77F (18°C-25°C)
Note:	Accuracy is given for one year, at 23°C ±
	2° RH<60%
This multimeter was designed to be safe at least under the following conditions
Indoor Use
Altitude:	up to 2000m
Pollution degree:	2
Ingress Protection Degree:	IP20

Important:

Read this operators manual thoroughly before using this multimeter. This manual is intended to provide basic information regarding this multimeter and to describe common test procedures which can be made with this unit.

Many types of appliance, machinery and other electrical circuit measurements are not addressed in this manual and should be handled by experienced service technicians.

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! WARNING Use extreme caution when using this multimeter. Improper use of this meter can result in severe damage to property, severe personal injury or death. Follow all instructions and suggestions in this operators manual as well as normal electrical safety precautions. Do not use this multimeter if you are unfamiliar with electrical circuits and proper test procedures.

2.1 For Your Safety

The marking “ ” on the multimeter represents Caution, risk of electric shock.

The marking “” on the multimeter represents Caution, risk of danger, important information, refer to the manual. In order to find out the nature of the potential HAZARD and any actions which have to be taken consult the manual in all cases where “” is marked.

The marking “ ” on the multimeter represents

Functional earth terminal.

The marking “ ” on the multimeter represents Equipment protected throughout by DOUBLE INSULATIONor REINFORCEDINSULATION. Measurement category II is for measurements performed on circuits directly connected to the low voltage installation. Examples are measurements on household appliances, portable tools and similar equipment.

1)Use extreme caution when checking electrical circuits.

2)! WARNING Do not stand in wet or damp work areas when working with electricity. Wear rubber-soled boots or shoes.

3)! WARNING Do not apply more voltage

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or current than the set range of the multimeter will allow.

4)! WARNING Do not touch the metal probes of the test leads when making a measurement.

5)Replace worn test leads. Do not use test leads with broken or tattered insulation. Only test leads meeting ETL, cETL, CE CAT II 500V IA can be used in this multimeter.

6)Discharge a capacitor before measuring it.

7)Remove the test leads from the circuit being measured as soon as the test is completed.

8) ! WARNING Do not measure voltage when the function/range switch is set on the resistance (ohms) or the current (mA) settings. Never measure current when the meter is set on the resistance range. Never measure AC voltage when the meter is set on DC voltage or DCmA. Setting the meter on the incorrect function may burn out some of the internal circuitry and may pose a safety hazard.

3. Operating Suggestions

1)Set the function/range switch to the proper position before making a measurement. When the voltage or current is not known, it MUST be determined that the capacity of the selected range will handle the amount of voltage or current in the circuit (see #3 under For Your Safety). Always start with the highest range in the function. If the

reading falls within the range of a lower setting, reset the function/range switch to

the appropriate setting for greater accuracy.

2)Avoid placing the meter in areas where vibration, dust or dirt are present. Do not store the meter in excessively hot, humid or damp places. This meter is a sensitive measuring device and should be treated with the same regard as other electrical and electronic devices.

3)Using the meter in areas with high magnetic fields can result in inaccurate readings. For greatest accuracy, lay the meter flat on a non-metallic surface.

4)When the meter is not in use, keep the function/range switch in the OFF position. This keeps the needle indicator from deflecting or ”bouncing” excessively.

5)When disconnecting the test leads from the unit, always grasp the leads where the input jacks meet the meter housing. Never pull the leads out of the jacks by the insulated wire or transport the meter using the test leads as a carrying strap.

6)Never immerse the meter in water or solvents. To clean the housing use a damp cloth with a minimal amount of mild soap.

7)If the resistance (ohms) function of the meter is not going to be used for a week or more, remove the internal battery to avoid potential leaks that may damage the unit.

3.1 Preliminary Adjustments

Fully seat the test leads in the correct input jacks. If necessary, using a small flat tip screwdriver, slowly turn the mechanical zero

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adjustment screw clockwise or counterclockwise until the needle indicator is directly over the three black zeros at the left end of the scale.

Analog Meter: Reading the Scale

	AC Voltage Scale
	Battery Test Scale	dB Scale for
		Transistor Gain
	General
		Measurement

Resistance (Ohms) Scale

}

DC Voltage

& Milliamps

Scale

Common Markings for both the AC & DC Voltage Scales

The first step in reading the analog scale is to align the needle with the scale. This is achieved by locating the mirror on the scale. Line the needle up with its reflection. When the reflection is hidden by the needle, the needle is properly aligned.

Resistance (Ohms - Ω)

Use the top scale for reading the resistance.

DC Voltage (V DC)

Use the middle scale directly below the resistance scale. Match the dial setting to the highest number on the scale. If the setting does not match one of the numbers, use a scale that can be easily multiplied to give the setting (i.e. - for 500V, use the 50V scale and multiply the reading by 10).

AC Voltage (V AC)

Use the same numbers and procedures as used for the DC voltage setting, but use the scale directly below the numbers.

DC Milliamps

Use the same scale and procedure as used for the DC voltage setting.

Decibel Gain (dB) - see pg. 14

Use the scale marked dB to read decibels for transistor gain. Use the chart at the right of the scale for proper conversion.

3.2 Internal Battery Condition

Before making resistance or continuity tests, check the condition of the internal battery. First turn the function/range switch to the ohms Rx1 position. Short the test leads together and the needle indicator should deflect to the right side of the scale. Keep the test leads shorted together while simultaneously turning the zero ohms adjustment dial until the needle indicator reads zero at the right side of the ohms (green) scale. If the needle will not zero, replace the battery with a new 1.5 volt AA size non-rechargeable battery (see Battery Replacement).

4. DC Voltage Measurement

1)Fully seat the test leads in the correct input jacks, (-) black lead, (+) red lead.

2)Set the function/range switch to the appropriate DC voltage range. If the voltage is unknown, use the highest range. If the

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voltage applied falls within the range of a lower setting, reset the function/range switch to the appropriate setting for greater accuracy.

3)If the polarity of the circuit to be tested is known, touch the black test lead to the neutral side. If the polarity is unknown, touch the test leads to opposite sides of the circuit. If the needle indicator deflects to the left of the scale, reverse the test leads.

Use the chart below as a guide to reading DC voltage measurements:

DC V		Read		and
range		following		multiply
setting		scale		reading by:
10		0-10		1
50		0-50		1
250		0-250		1
500		0-50		10

5. DC Milliamp Measurement

1)Fully seat the test leads in the correct input jacks, (-) black lead, (+) red lead.

2)Set the function/range switch to the 250 DCmA setting.

3)Touch the test leads to the circuit in series (in line with the circuit) so that the circuit current passes through the multimeter in order to make the measurement. If the needle indicator deflects to the left, reverse the test leads.

DC mA	Read	and
range	following	multiply
setting	scale	reading by:
250	0-250	1

Common DC Milliamperage

Measurements

It is important to point out that milliamps can also be expressed as thousandths of an Ampere; therefore 250 milliamps is 250 thousandths of one Amp. The 250mA function of your multimeter is commonly used by electronics repair technicians and hobbyists to troubleshoot various low voltage circuits. Although not normally used for electrical troubleshooting around the home, this function can be used to measure the milliamperage draw of household items such as flashlights, and other battery operated devices that do not draw more than 250 mA. In fig. 2 the red (+) test lead is hooked up to the (+) terminal of the lantern battery while the black (-) test lead is hooked up to the bulb. The meter will indicate the milliamperage draw when the flashlight switch is thrown in the ON position.

Figure 2

! WARNING Do not apply voltage to the test leads while the meter is set in the milliamp range. See #8 For Your Safety.

6. AC Voltage Measurement

1)Fully seat the test leads in the correct input jacks (-) black lead, (+) red lead.

2)Set the function/range switch to the appropriate AC voltage range. If the

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voltage is unknown, use the highest range. If the voltage applied falls within the range of a lower setting, reset the function/range switch to the appropriate setting for greater accuracy.

3)Touch the test leads to the circuit under test. With AC voltage, the polarity of the test leads is not a factor.

Use the chart below as a guide to reading AC voltage measurements:

AC V		Read		and
range		following		multiply
setting		scale		reading by:
10		0-10		1
50		0-50		1
250		0-250		1
500		0-50		10

Common AC Voltage Measurements

6.1 Wall Receptacles

If the receptacle is controlled by a switch, make sure the switch is ON. Set the function/range switch to 250V AC. Touch the test leads to the “hot” and “neutral” slots of the receptacle (see fig. 3A). The needle indicator should read 120V AC on the 0-250 scale. To test for proper grounding of the receptacle, touch one test lead to the “hot” (narrow) side of the receptacle, and

Figure 3

3B

3A

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the other test lead to the ground slot. The meter should read 120V AC as before.

7. Resistance/Continuity Measurement

For resistance and continuity testing POWER MUST BE OFF:

1)Fully seat the test leads in the input jacks (-) black lead, (+) red lead.

2)Set the function/range switch to the desired position and short the test leads together. Using the zero ohms adjustment dial, slowly turn the dial until the needle indicator reads -0- ohms at the right end of the ohms scale. If the needle will not zero, replace the internal battery with a new 1.5 volt AA size non-rechargeable battery (see

Battery Replacement).

3)Touch the test leads to the resistance or nonenergized circuit to be measured. Measure the value of the reading on the green ohms scale and multiply the reading by 1/10/100. If you’re making basic continuity tests, the needle indicator should move all the way to the right side of the ohms scale if continuity exists.

Note: When switching the unit back and forth from ohms to other functions, always zero the needle indicator before taking another reading. Failure to zero the needle before taking resistance/continuity measurements will result in inaccurate readings.

Continuity tests are probably the most frequently performed electrical troubleshooting procedures around the home. ALWAYS REMEMBER THAT

CONTINUITY CHECKS ARE TO BE MADE WITH THE POWER TO THE CIRCUIT

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TURNED OFF. Polarity of the test leads is not a factor in making continuity checks.

7.1 Extension Cords

Unplug the cord. Set the function/range switch to the Rx1 position. Touch one of the test leads to one of the metal prong ends of the cord, and insert the other test lead in either one of the receptacle slots on the other end of the cord, making sure the test lead is making good contact with the receptacle (see fig. 4). If the needle indicator does not move to -0- ohms, insert the test lead into the other receptacle slot, again making sure of good contact. If the needle indicator still does not move the cord has a break and should be replaced.

Figure 4

7.2 Fuses

Note: With the power OFF, always remove a fuse from its socket before testing it. With cartridge fuses, touch the test leads to each end of the fuse (see fig. 5). If the fuse is good, the needle indicator will move to -0- ohms. If not, replace the fuse. On plug-type fuses, touch the the test leads on the bottom contact and the other on the threaded metal contact (see fig. 6).

Figure 5

Figure 6

7.3 Switches

Cut off the power source to the switch. If necessary, remove the switch. Turn the switch to the ON position and touch the test leads to the switch terminals (see fig. 7). If the switch is good, the needle indicator will move to -0- ohms. If not, replace the switch. On other switches such as three-way light switches or double pole double throw (ON-OFF-ON) switches, each ON position will need to be tested. Alternate the test leads between the switch terminals to determine which two terminals control that ON

Figure 7

8. Decibel Measurement

The decibel feature of this multimeter is for transistor gain measurement in electronic circuits and should not be confused with audio decibels. This function is used primarily by electronics technicians to measure the power gain in transistors, and is rarely encountered in home project applications.

1)Fully seat the test leads in the correct input jacks, (-) black lead, (+) red lead.

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