Tenma 72-6947 User manual

AUDIO IMPEDANCE TESTER
INSTRUCTION MANUAL
AUDIO IMPEDANCE TESTER
CAT.III 100V
OFF
72-6947
20W200W
COM
TEST ON /OFF
2000W
HOLD
-+
DATA HOLD
MODEL 72-6947
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AUDIO IMPEDANCE TESTER
CAT.III 100V
OFF
72-6947
20W200W
COM
TEST ON /OFF
2000W
HOLD
-+
DATA HOLD
(1) Test Lead Connection
(2) LCD Display
(3) TEST ON/OFF switch
(4) DATA HOLD button
(5) Rotary switch for range selection
(1)
(5)
(4)
(3)
(2)
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• WARNING! Read the following safety information carefully
before attempting to operate or service the meter.
• Use the meter only as specified in this manual: otherwise the
protection provided by the meter may be impaired.
•Rated environmental conditions :
(1). Indoor use.
(2). Installation CAT. III 100V.
(3). Pollution Degree 2.
(4). Altitude up to 2000 Meter.
(5). Relative Humidity 80% Max.
(6). Ambient Temperature 0°C~40°C.
•Observe the International Electrical Symbols listed below.
Meter is protected throughout by double insulation or
reinforced insulation.
Warning ! Risk of electric shock.
Caution ! Refer to this manual before using the meter.
Note Do not use on Live system.
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1. Safety Notes
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• True measurement of speaker systems actual impedance at 1kHz.
•Three test ranges (20W/200W/2000W) allow testing of home
theater and commercial sound systems.
•Convenient portable battery operation.
•Low battery indication.
•Data hold function.
•Timer function provides continuous hands free operation. The timer will
last 3-5 minutes after presssing TEST ON/OFF button.
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2. Features
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•Measurement Range:
20W/200W /2000W
•Test frequency:
1kHz
•Accuracy:
20W: ± 2%rdg ± 2dgt or ± 0.1W, which is greater.
200W/2000W: ± 2%rdg ± 2dgt
•Protection:
Meets IEC-1010(EN61010),Installation CAT. III 100V
•Power Requirements:
9VDC(6 x1.5V AA” UM-3 batteries)
•Dimensions
8" (H) x 31/2" (W) x 23/16" (D)
•Included Accessories:
Test leads, instruction manual, carry case
•Low battery indication
“ “ symbol appears on the display
•Data hold indication :
“ HOLD " symbol appears on the display
•Display :
LCD 3 1/2 digit (2000 counts)
•Weight :
Approx. 1.2 lbs. (battery included)
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3. Specifications
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PRIOR TO USE, READ SAFETY
NOTES ON PAGE 2.
1. Ensure the system under test is not live.
2. If prior to use, the
display, batteries should be replaced.
3. Set the function switch to suitable range then press the
pushbutton to test and take the reading.
4. Measuring Methods
" " symbol appears on the
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AUDIO IMPEDANCE TESTER
CAT.III100V
OFF
72-6947
20W200W
COM
TEST ON / OFF
2000W
HOLD
-+
DATAHOLD
Measuring an Individual Speaker
4. Individual speakers are typically between 2Wand 16W. For these
types, the 20Wsetting should be used. Some special application speakers
may be of much higher impedance. Speakers of up to 2KW(2000W) may
be measured using the 200Wor 2000Wsetting. These higher settings also
allow measurement of speakers when connected to impedance matching
transformers or volume controls. In these cases, the speaker should be
connected to the meter as shown.
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(10 W)
(50 W)
(200W)
AUDIO IMPEDANCE TESTER
CAT.III100V
OFF
72-6947
20W200W
COM
TEST ON / OFF
2000W
HOLD
-+
DATAHOLD
Measuring 25V/70V Distributed Speaker Systems
5. Large distributed systems typically utilize 25.2V or 70.7V transformers 
(50V and 100V in Europe), to greatly ease the connection of multiple 
speakers and facilitate long cable runs. These speakers are connected in 
parallel, as shown, with total wattage ratings added to calculate the overall 
rating of the system. Connecting this meter to a speaker arrangement 
such as this will provide the overall impedance of the system.
Using the formula shown below you can calculate the wattage.
Simply put, when connected to a distributed system, take the voltage 
of the system (normally 70.7V or 25.2V), squared, divided by the 
impedance displayed on the meter. Your answer will be the total 
system wattage. This total wattage must not exceed the wattage 
output rating of the amplifier, or damage may occur.
E
—= P
Z
E = Voltage Z = Impedance P = Wattage
2
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• Battery Replacement :
When the
as follows :
(1) Disconnect the test leads from the instrument
and turn off the power.
(2) Remove the two screws, located at the bottom of the rear panel.
(3) Slide the battery door straight down.
symbol " " appears on the display, replace with new
batteries.
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5. Maintenance
•Cleaning and storage :
WARNING
To avoid electrical shock or damage to the meter, do not allow
water or excessive moisture inside the case.
Periodically wipe the case with a damp cloth and detergent : do not
use abrasives or solvents.
If the meter is not to be used for periods of longer than 60 days,
remove the batteries and store them separately.
TENMA TEST EQUIPMENT
900 SOUTH POINEER BLVD.
SPRINGBORO, OHIO 45066
(4) Replace with six "AA" type alkaline batteries. Do not mix with
other battery types or mix old and new batteries.
(5) Replace battery door and screws.
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