B&K Precision 1743B User's Manual
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INSTRUCTION
MANUAL
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Model%1743B%
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2
TEST INSTRUMENT SAFETY
WARNING%
Normal use of test equipment exposes you to a certain amount of danger from electrical shock because testing must sometimes be
performed where exposed high voltage is present. An electrical shock causing 10 milliamps of current to pass through the heart will stop
most human heartbeats. Voltage as low as 35 volts dc or ac rms should be considered dangerous and hazardous since it can produce a
lethal current under certain conditions. Higher voltages are even more dangerous. Your normal work habits should include all accepted
practices to prevent contact with exposed high voltage, and to steer current away from your heart in case of accidental contact with a
high voltage. Observe the following safety precautions:
1.&There is little danger of electrical shock from the dc output of this power supply. However, there are several other possible test
conditions using this power supply that can create a high voltage shock hazard:
a.&If the equipment under test is the “hot chassis” type, a serious shock hazard exists unless the equipment is unplugged (just turning
off the equipment does not remove the hazard), or an isolation transformer is used.
b.&If the equipment under test is “powered up” (and that equipment uses high voltage in any of its circuits), the power supply outputs
may be floated to the potential at the point of connection. Remember that high voltage may appear at unexpected points in
defective equipment. Do not float the power supply output to more than 100 volts peak with respect to chassis or earth ground.
c.&If the equipment under test is “off” (and that equipment uses high voltage in any of its circuits under normal operation), discharge
high-voltage capacitors before making connections or tests. Some circuits retain high voltage long after the equipment is turned
off.
2.&Use only a polarized 3-wire ac outlet. This assures that the power supply chassis, case, and ground terminal are connected to a good
earth ground and reduces danger from electrical shock.
3.&Don’t expose high voltage needlessly. Remove housings and covers only when necessary. Turn off equipment while making test
connections in high-voltage circuits. Discharge high-voltage capacitors after removing power.
(continued on inside back cover)
3
TABLE OF CONTENTS
Page
TEST INSTRUMENT SAFETY -------------- inside front cover
INTRODUCTION -------------------------------------------------- 4
FEATURES ---------------------------------------------------------- 5
SPECIFICATIONS ------------------------------------------------- 6
CONTROLS AND INDICATORS -------------------------------- 8
OPERATING INSTRUCTIONS -------------------------------- 10
Safety Precautions ---------------------------------------------- 10
Equipment Precautions ---------------------------------------- 10
Hook-Up --------------------------------------------------------- 10
Typical Constant Voltage Operation ------------------------- 13
Setting Current Limit ------------------------------------------ 14
Typical Constant Current Operation ------------------------- 15
Constant Voltage/Constant Current Characteristic --------- 16
Connecting Two Power Supplies in Series ------------------ 16
Connecting Two Power Supplies in Parallel ---------------- 19
Page
APPLICATIONS ------------------------------------------------- 20
General --------------------------------------------------------- 20
Electronics Servicing ----------------------------------------- 20
Electronics Manufacturing ----------------------------------- 20
Electronics Design Lab --------------------------------------- 20
Electronics Education ----------------------------------------- 21
Battery Charging ---------------------------------------------- 21
MAINTENANCE ------------------------------------------------ 22
Fuse Replacement --------------------------------------------- 22
Line Voltage Conversion ------------------------------------- 22
Adjustments ---------------------------------------------------- 22
1743B Calibration --------------------------------------------- 23
Instrument Repair Service ------------------------------------ 23
WARRANTY SERVICE INSTRUCTIONS ------------------ 25
LIMITED TWO-YEAR WARRANTY ------------------------ 26
INTRODUCTION
The B+K Precision Model 1743B DC Power Supply is a high
quality, general purpose dc power source. It provides 0-35 volts
dc output, adjustable with both coarse and fine voltage controls
for precise settability. The current output is 0-6 amps, adjustable
with both coarse and fine current controls. Two large LED
meters continuously monitor the output voltage and current. The
VOLTAGE meter is green, while the CURRENT meter is red.
The Model 1743B exhibits excellent regulation and low ripple
characteristics. The circuit design incorporates a pre-regulator,
which greatly reduces internal power dissipation at low output
voltages. The styling is both attractive and functional.
This instrument may be used in constant voltage or constant
current applications. The crossover from constant voltage to
constant current modes is smooth and automatic. LED’s indicate
the “CV” (constant voltage) or “CC” (constant current) mode of
operation. In constant voltage applications, a current limit may
be preset. When load variations cause the current to reach the
preset limit, the unit then regulates output current rather than
output voltage.
Current limits are adjustable from 5% to 100% of maximum.
In constant current applications, the maximum voltage may
be preset. When load variations cause current to drop below
the regulated value, the unit reverts to regulated voltage
operation at the preset value.
Reverse polarity protection prevents accidental damage to
the power supply from improper connection to an external
voltage, and current limiting protects the equipment being
powered, as well as the power supply.
The output is isolated from chassis and earth ground,
which permits full flexibility of connections. When needed,
the (+) or (-) polarity may be strapped to ground, or either
polarity may be floated to an external voltage. Two supplies
may be connected in series as a 0-to-70 volt power source, or
two supplies may be connected in parallel, with suitable
balancing resistors, for up to twice the output current.
This power supply is well suited for a wide variety of
electrical and electronics applications, including service
shops, engineering labs, production testing, school
laboratories, and home use by hobbyists.
4
5
FEATURES
0"35%VOLTS&
Continuously variable over 0-to-30 volt range with coarse and fine
controls.
0"6%AMPS%
0-to-6 amps current rated for continuous duty at full output current.
Coarse and fine current adjust controls.
LABORATORY%QUALITY%
Excellent regulation, low ripple.
CONSTANT%VOLTAGE%OR%CONSTANT%CURRENT%
&
Provides regulated dc voltage output or regulated dc current output.
Crossover is smooth and automatic.
LED%DISPLAYS&
Two large, easy-to-read LED digit displays monitors output voltage
and output current, and provides good visibility in bright or low
light.
LED%INDICATORS%
Act as pilot light and identify mode of operation and metering.
PRE"REGULATOR&
Limits internal dissipation for higher reliability.
ISOLATED%OUTPUT&
Either polarity may be floated or grounded.
OVERLOAD%PROTECTION%
Fully adjustable current limiting (from 5% to 100% of
maximum output current) protects circuit under test and the
power supply.
REVERSE%POLARITY%PROTECTION%
Prevents damage to power supply from external voltage of
reverse polarity.
STYLING%
Modern functional styling. Logical, convenient layout of
controls.
SPECIFICATIONS
OUTPUT VOLTAGE: 0 to 35 VDC, coarse and fine
adjustment.
OUTPUT CURRENT: 0 to 6 A, coarse and fine
adjustment.
CONSTANT VOLTAGE OPERATION
Voltage Regulation
Line (108-132 V): ≤ 0.2% +2 mV
Load (no load to full load): ≤0.04% + 2 mV
Recovery Time: ≤100 µs typical.
Ripple Voltage
RMS: ≤1 mV.
Temperature Coefficient
(0° to +40 °C): ≤300 PPM/°C
CONSTANT CURRENT OPERATION
Adjustable Current Limits: 5% to 100%
Current Regulation
Line (108-132 V): ≤0.4% + 5 mA
Load ≤0.4% + 5 mA
Current Ripple: ≤3 mA typical.
METERING
Voltmeter 4 digit Green LED Display
Range: 0 to 99.99 V.
Accuracy: (0.5% + 9 digits)
Ammeter 4 digit Red LED Display
Hi Range: 0 to 9.999 A.
Accuracy: (0.5% + 9 digits).
AC INPUT:
Domestic: 120 VAC ±10%, 60 Hz
International: 120/220/230/240 VAC - 10%, 50/60 Hz
POWER CONSUMPTION: Approximately 420 W or less at
full load.
PROTECTION: Reverse polarity protection,
Current limiting.
6
7
SPECIFICATIONS
NOTE: Specifications and information are subject to change without notice. Please visit www.bkprecision.com for the most current
product information.
Note 1:
Important: Even with noticeable Thermal Drift, this high resolution power supply will be considerably more accurate than any standard
three digit display bench power supply.
Thermal Drift: Since this power supply has greater resolution than standard bench power supplies they are more susceptible to Thermal
Drift. Thermal Drift occurs on almost every type of power supply but is more apparent on high resolution types. Thermal Drift results in the
metering of the power supply to either slowly increase or decrease with the change in the power supply’s internal temperature. As the power
supply outputs more power its internal temperature will increase causing the metering (primarily the current) to slowly increase. As the
power demand is deceased the power supply will cool causing the metering (primarily the current) to slowly decrease. If the power supply
remains with a constant output of power for more than fifteen minutes the power supply metering will remain constant and should not
continue to drift.
TEMPERATURE RANGE
Operation: 0° to +40° C, ≤75% R.H.
Storage: -15° to +70° C,≤ 85% R.H.
DIMENSIONS (HxWxD): 5.7” x 10.5” x 15” (145 x 267 x 38 mm)
WEIGHT: 24 lb. (10.4g)
ACCESSORIES SUPPLIED: Instruction Manual,
Spare Fuse
8
CONTROLS AND INDICATORS
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Either the “CC” or “CV” and the LED indicators will be lit
whenever the unit is operating, thus serving as a pilot light. The unit
automatically changes from CV to CC operation when the preset
current limit is reached.
1.&C.C. (Constant Current) Indicator. Red LED lights in constant
current mode. Unit regulates output current at value set by CURRENT controls.
2.&C.V. (Constant Voltage) Indicator. Green LED lights in constant
voltage mode. Unit regulates output voltage at value set by
VOLTAGE controls.
3.&GREEN LED Display. 4 digit display continuously monitors
voltage.
4.&RED LED Display. 4 digit display continuously monitors
current.
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5.&Coarse Control. Coarse adjustment of output voltage. Read value
on GREEN LED display.
6.&Fine Control. Fine adjustment of output voltage. Read value on
GREEN LED display.
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7.& Coarse CURRENT Control. Adjusts current limit in
constant voltage mode. Adjusts constant current value
in constant current mode. Current can be read from
RED LED display.
8.& Fine Control. Fine adjustment of current limit or current
value. Current can be read from RED LED display.
OUTPUT%TERMINALS%
9.& “+” Terminal (Red). Positive polarity output terminal.
10.& GND Terminal. Earth and chassis ground.
11.& “-” Terminal (Black). Negative polarity output
terminal.
REAR PANEL CONTROLS
12.% Fuse
13.% Power Cord
9
CONTROLS AND INDICATORS
Figure 1. Front Panel Controls and Indicators.
Figure 2. Rear Panel
REAR%PANEL%CONTROLS%
7.& Fuse.
8.& Power Cord.
9.& 110/220 Line Voltage Conversion Switch.