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INSTRUCTION MANUAL
VOM-MULTITESTER 20,000 ohms/volt DC model HM-102BZ
ALTAI
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DESCRIPTION
The VOM-MULTITESTER model HM-102BZ is a compact and reliable bench type multimeter designed service a wide variety of equipments.
This wide range multimeter features a mirror-back scale, double-jewelled precision moving-coil movement and overload protection system with dual silicon diode and 1 Amp fuse.
High 20,000 ohms/V DC and 8,000 ohms/V AC sensitivities minimize the circuit loading.
As the additional functions, Battery test function and DC 10 Amp scale extend measurement capability of the meter.
Also the Buzzer function offers an audible signal for continuity open-short quick test.
If it is kept clean and is not subjected to extreme shock or continuous vibration the HM-102BZ will give you many years of trouble free service.
SPECIFICATION
ELECTRICAL
Range
: 23 measuring ranges
DC Voltage
: 0-2.5-10-50-250-1000V
AC Voltage
: 0-10-50-250-1000V
DC Current
: 0-5-50-500mA, 10A on seperate jack.
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Resistance
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: Rx1, Rx10, Rx1K (Center 5012)
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Decibel
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: -8 dB to + 62dB on all AC V range
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BAT test
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: 1.5V size AA ; Internal loading resistance
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and current 75 ohm/20mA
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( ) And and
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9V Standard: Internal loading resis-
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tance and current 450 ohm/20mA
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Audio power
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level : _8 dB to + 22dB on a 600
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Audio power
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obm line on separate jack
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Acouracios
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· DC V/A 4% ES AC V E% ES Obm 4°
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Accuracies
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Are of coold length
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Constitution
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Arc of scale length.
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Sensitivity
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: 20,000 onms/v DC, 8,000 onms/v AC.
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DUVCIONI
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PHYSICAL
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Front panel co
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ontrols : Range-Function switch, Ohms
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Adjust.
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Movement
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: Moving Coil - 90° Arc, 40 uA FS.
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Operating pos
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ition : Horizontal or Vertical
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Operating Ten
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nperature : 18°-25°C for rated accuracy.
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Batteries
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: 1.5V AA x 2 pcs.
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Protection '
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: 2A/250V Fuse and Silicon double
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diode.
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Construction
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: High impact plastic and phenolic PCB
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and rugged handle for bench-top use
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or carrying.
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Size
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5-1/4" x 3-1/2" x 1-1/2"
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Tht
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: 12 lbs (including battery)
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ynt
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. 1.2 Ibs. (including battery)
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FRONT PANEL FEATURES
Range-Function switch : Used to select factor and range to be measured.
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OΩ ADJ: Used to set pointer O (extreme right meter scale) on uppermost Ω scale when test leads are shorted together in an Ohms setting of the range.
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Mechanical Adjust: Screw located on the meter movement to set pointer to zero mark at the scale.
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10A Jack: Plug-in connection for Red, positive test lead when measuring DC current over 0.5A up to 10A, range switch must be set to 10A poisition.
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OUT Jack: Plug-In connection for Red test lead when measuring audio output. Range switch must be set to AC V ranges.
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A-Ω-V Jack: Plug-in connection for red test lead when measuring current, resistance and AC, DC Voltage.
COM/+Ω Jack: Plug-in connection for Black, negative test lead for all measurement.
OPERATING PROCEDURES
PRELIMINARY ADJUSTMENT
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Perform the mechanical adjust screw setting as follows:
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a. Place the HM-102BZ tester flat on a bench
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b. Set the range switch to OFF.
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c. Short two test prods together.
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d. Note if the meter pointer indicates exactly "O" at the extreme left end of the black scale .
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e. If it does not read O, turn the screw on the meter movement slowly cw or ccw until the proper "O" reading is obtained.
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2. Check the internal batteries as follows;
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a. Short two test prods together.
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b. Set the Range switch to Rx1.
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c. Turn the OΩ ADJ control until the pointer reads exactly O ohm at the right end of Ω scale. If the pointer can not be brought to the "O" mark, replace 1.5V AA cells (see MAINTENANCE)
OPERATING SUGGESTIONS
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1. Set the range switch to the proper position before making any measurement.
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Never apply more voltage or current than the amount noted in each position.
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3. When the voltage or current to be measured is not known, always start with the highest range in each case.
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4. For most accurate readings, look at the so from the point where the pointer and its reflection on the mirror come together to avoid parallax error. Also use a range setting that results in a reading in the upper 1/3rd of the meter scale.
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5. Always observe correct test lead polarity when making DC voltage and currents.
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6. Keep the Range selector switch to OFF position when the tester is not in use or during transit.
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Remove the batteries before storing the tester for a a long period of time.
CAUTION
Before operate the tester read PRECAUTIONS. Failure to use the tester in complete accordance with those precautions could result in severe electrical shock and/or damage to the tester.
DC VOLTAGE MEASUREMENT
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1. Select the required DC voltage range.
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Plug the black test lead into the -COM/+Ω j; and the red test lead into the +A-Ω-V jack.
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3. If you know the polarity of the circuit to be tested, connect the black probe to the negative side and red probe to the positive side of the circuit
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If you don't know the polarity, connect the
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probes to each side of the circuit and watch the pointer. If it reflects to the left, reverse the probes. The red probe will now be connected to the positive side.
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5. Read DC voltage on the appropriate scale.
DC CURRENT MEASUREMENT
CAUTION
Never connect the test leads directly across any voltage when the tester is used as a current meter, this could damage the instrument. Always connect the meter in series with the load.
1. Select the required DC current range
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2. Plug the black test lead into the -COM/+Ω jack and the red test lead into the +A-Ω-V jack.
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3. Using the test leads, connect the meter in series with the circuit under test. If the pointer deflects to the left, reverse the test prods.
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4. Read DC current on the appropriate DC mA scale.
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DC 10Amp MEASUREMENT
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1. Set the selector switch to 10A position.
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Insert the red test lead into the 10A jack, the black test lead into the -COM/+Ω jack.
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Follow the procedures of DC current measurement steps 3 and 4 above.
AC VOLTAGE MEASUREMENT
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1. Set the selector switch to the appropriate AC V range. If the voltage is unknown use the highest range
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2. Plug the leads into the jacks and place test prods on each side of the AC voltage to be measured (polarity of test probes is unimportant on AC voltages)
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3. Read AC voltage on the appropriate scale.
RESISTANCE MEASUREMENT
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1. Set the selector switch to the appropriate OHM range.
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Short two test prods together, pointer should be read zero at the right end of the scale.
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If pointer does not indicate zero, adjust O Ω ADJ control to line up with "O" on Ω scale.
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If pointer can not be brought to "O", replace batteries. (see MAINTENANCE)
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Seperate the test leads and connect them across the resistor to be measured.
(pidae.
switch.
When switching ranges, readjust pointer to "O" ohm each time as outlined above.
NOTE
NOTE
Disconnect all power from resistor to be measured before
Take reading on Ω scale and multiply the reading
by the multiplication factor indicated by the selector
DB RATIO MEASUREMENT
applying the test prods.
For some applications, output voltage and audio frequency voltage are frequently measured in terms of decibels. The decibel scale (dB) is numberd from -8 up to + 22.
To measure decibels read the dB Arc after proceeding to instructions for AC voltages. The dB scale is calibrated for direct reading on the lowest AC volt range (10 AC V).
Scale factors for other AC V ranges are given in the table on scale plate. The appropriate number of dB as within in the table on scale plate is added.
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BATTERY MEASUREMENT
CAUTION
Do not keep the leads connected to the battery for longer time than is necessary to determine its condition.
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1. Set the selector switch to the position for testing the battery in question.
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2. Remove the battery from the unit in which it is used.
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Connect the black probe to the negative side and red probe to the positive side of the battery.
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Note the reading on the "BAT" meter scale. If the pointer indicates in green area or above, the battery is in good condition.
If the pointer indicates in red area the battery is too weak, so it should be replaced. When the pointer stops in white area (marked ) the battery condition is marginal. It is likely that the battery will not perform properly for a reasonable period of time in the equipment in which it is being used and probably should be replaced.
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BUZZER OPERATION
CAUTION
Disconnect power from any resistor or circuit to be measured before measuring resistance and operating the buzzer.
The meter is provided with a self contained buzzer actuated by the internal battery. On this function HM-102BZ operates as a continuity open-short tester by means of audible signal.
When the test leads are connected across any conductor or circuit which has resistance less than 100 ohms the buzzer generates audible signal, so you can make continuity check very easily and quickly without observing meter scale.
NOTE
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Do not operate the buzzer continuously as this will wear out the battery.
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OUTPUT VOLTAGE MEASUREMENT
A condenser is interconnected in series with the OUTPUT and + A-Ω-V terminal to cut off DC elempresent on the circuit to read AC signal alone on the meter.
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1. Set the function switch at desired AC range position.
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Plug the black test lead into the COM/+Ω, red test lead into the OUT jack.
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3. Connect the black test lead to grounded side of the circuit to be measured and the red test lead to the "HOT" side.
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4. Turn on the power in the circuit. Read the output voltage on the AC voltage scale.
MAINTENANCE
GENERAL
No periodic maintenance is required other than replacement of battery, fuse and visual inspection of the TESTER .
Keep instrument clean and dry. Do not use solvent to clean, use damp cloth.
The only field replaceable parts are two 1.5V "A. cells and 2A/250V fuse.
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BATTERY REPLACEMENT
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1. Remove a screw in the rear cover of the case and lift the back off the front section.
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Note the orientation of the AA cells in their compartment. Replace battery observing polarities marking on the bottom of the battery compartment.
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Carefully replace the rear cover back. Retighten the screw. Do not tighten excessively or you will strip the threads in the case.
FUSE REPLACEMENT
To replace fuse, perform the procedures discribed above. Replace blown fuse with a new 2A/250V or equivalent only.
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