BK Precision BK Precision 1735A Manual

INSTRUCTION

MANUAL

El Manual de la Instrucción

Manual de Instruccion

TestEquipmentDepot.com

MODEL 1735A

MODELO 1735A

0-30V, 0-3A

DC POWER SUPPLY

With Dual 4-Digit LED Displays

Fuente de poder DC

Con doble LED indicador

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

TestEquipmentDepot.com

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)

2

Instruction Manual

for

Model 1735A

0-30 V, 0-3 A

DC POWER SUPPLY

With Dual LED Display

3

TABLE OF CONTENTS

Page

Page

TEST INSTRUMENT SAFETY ----------------inside front cover

INTRODUCTION------------------------------------------------------5

FEATURES -------------------------------------------------------------6

SPECIFICATIONS ----------------------------------------------------7

CONTROLS AND INDICATORS----------------------------------9

OPERATING INSTRUCTIONS---------------------------------- 11

Safety Precautions--------------------------------------------------11
Equipment Precautions--------------------------------------------11
Hook-Up -------------------------------------------------------------11
Typical Constant Voltage Operation -------------------------- 14
Setting Current Limit ----------------------------------------------15
Typical Constant Current Operation--------------------------- 16
Constant Voltage/Constant Current Characteristic----------17
Connecting Two Power Supplies in Series------------------- 17
Connecting Two Power Supplies in Parallel------------------20

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

TestEquipmentDepot.com

APPLICATIONS ----------------------------------------------------21

General--------------------------------------------------------------21
Electronics Servicing --------------------------------------------21
Electronics Manufacturing--------------------------------------21
Electronics Design Lab------------------------------------------22
Electronics Education --------------------------------------------22
Battery Charging--------------------------------------------------22

MAINTENANCE----------------------------------------------------23

Fuse Replacement ------------------------------------------------23
Line Voltage Conversion----------------------------------------23
Adjustments--------------------------------------------------------23
1735A Calibration ------------------------------------------------26

Instrument Repair Service

--------------------------------------25

4

The

B+K Precision

Model

1735A

DC Power Supply is a high

Current limits are adjustable from 5% to 100% of maximum.

INTRODUCTION

quality, general purpose dc power source. It provides 0-30 volts
dc output, adjustable with both coarse and fine voltage controls
for precise settability. The current output is 0-3 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 1735A 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. The
mechanical configuration conserves bench space and allows for
easy portability.

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.

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 sup plies
may be connected in series as a 0-to-60 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.

5

FEATURES

0-30 VOLTS

LED INDICATORS

Continuously variable over 0-to-30 volt range with coarse and fine
controls.

0-3 AMPS

0-to-3 amp 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.

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. Configuration conserves bench
space and aids portability. Logical, convenient layout of
controls.

6

OUTPUT VOLTAGE:

0 to 30

VDC, coarse and fine

Line (108

-

132

V): 0.2% + 3mA

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

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SPECIFICATIONS

adjustment.

OUTPUT CURRENT: 0 to 3A, coarse and fine adjustment.

CONSTANT VOLTAGE OPERATION

Voltage Regulation
Line (108-132 V): 0.01% + 3mV.
Load (no load to full load): 0.01% + 3mV.

Recovery Time: 100 µs typical.

Ripple Voltage
Peak-to-Peak: 2mV, typical
RMS: 1mV.

Temperature Coefficient

(0° to +35 °C): 300 PPm/°C

CONSTANT CURRENT OPERATION

Adjustable Current Limits: 5% to 100%
Current Regulation

Load 0.2% + 3mA

Current Ripple: 3mA 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
Range: 0 to 9.999A.
Accuracy: (0.5% + 9 digits)*.
(* = see note 1 at end of specifications)

POWER REQUIREMENTS:

Domestic: 120 VAC ±10%, 60 Hz
International: 120/220/230/240 VAC - 10%, 50/60 Hz

POWER CONSUMPTION: Approximately 180W or less at

full load.

PROTECTION: Reverse polarity protection,

Current limiting.

7

SPECIFICATIONS

TEMPERATURE RANGE

WEIGHT:

10.5 lb.

Operation: 0° to +40° C, 75% R.H.
Storage: -15° to +70° C, 85% R.H.

DIMENSIONS (HxWxD): 6.2 x 5.5 x 12.5"

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.

ACCESSORIES SUPPLIED: Instruction Manual,

Spare Fuse

8

INDICATORS

CURRENT CONTROL

CONTROLS AND INDICATORS

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.

VOLTAGE CONTROLS

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.

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. Adjusts current limit in constant voltage

mode. Adjusts constant current value in constant current
mode. Current can be read from RED LED display.

POWER CONTROLS

9. ON-OFF Switch.

OUTPUT TERMINALS

10. “+” Terminal (Red). Positive polarity output terminal.

11. GND Terminal. Earth and chassis ground.

12. “-” Terminal (Black). Negative polarity output

terminal.

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