B&K Precision 1686A User Manual

1

INSTRUCTION

MANUAL

MODEL 1686A

3 to 14 VOLT

DC POWER

SUPPLY

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 hear t 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 voltage poses an even greater threat because such voltage can more easily
produce a lethal current. Your normal work habits should include all accepted practices that will prevent contact with exposed high
voltage, and that will steer current away from your heart in case of accidental contact with a high voltage. You will signifi cantly
reduce the risk factor if you know and 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 the precautions of step 8 are observed.

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 point s
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 rear cover)

3

Instruction Manual

for

MODEL 1686A

3 to 14 VOLT

DC POWER SUPPLY

22820 Savi Ranch Parkway

Yorba Linda, California 92887

4

page

TEST INSTRUMENT SAFETY................................ inside front cover

INTRODUCTION.................................................................................5

SPECIFICATIONS................................................................................6

CONTROLS AND INDICATORS........................................................7

OPERATING INSTRUCTIONS...........................................................9

Safety Precautions..............................................................................9

Equipment Protection Precautions.....................................................9

Power Supply Hook-up and Operation..............................................9

Considerations..................................................................................10

Current Limiting..............................................................................11

Connecting Two Supplies in Series.................................................11

Connecting Two Supplies in Parallel...............................................11

page

MAINTENANCE............................................................................14

Fuse Replacement........................................................................14

Line Voltage Conversion.............................................................14

Adjustments.................................................................................14

Case Disassembly........................................................................14

Voltage and V Meter Adjustments..............................................15

Current and A Meter Adjustments...............................................15

Instrument Repair Service...........................................................16

SERVICE INFORMATION.......................................................... 17

LIMITED ONE-YEAR WARRANTY.......................................... 18

TABLE OF CONTENTS

5

INTRODUCTION

The B+K Precision Model 1686 is a high quality 3 to 14 Volt

DC Power Supply primarily designed for bench powering of
automotive and marine electronic equipment. The Model 1686
has a maximum output current proportional to the voltage setting,
the maximum current of 12 amps available from 13.8 to 14 volts
and is reduced to 2.5 amps at 3 volts. Two panel mounted meters
continuously monitor the output voltage and current.

The 12-amp output of the Model 1686 power supply allows
bench powering of most any car radio, sound system (including
most “high-power” car stereo receiver/amplifiers), tape systems,
PA systems, and low-to -medium power 2-way radios, such as CB
transceivers, VHF/UHF commercial equipment, marine, car
telephone, and 2-meter transceivers.

The power supply utilizes thermostatically controlled fan
cooling for improved heat dissipation and reliability while
keeping bulk and weight to a minimum.

Foldback current limiting protects the power supply from
accidental short circuits and overload conditions. The output is
isolated from chassis and earth ground, permitting full
flexibility of connections. When desired, the positive (+) or
negative (–) polarity outputs may be strapped to ground,
allowing use with negative-ground and positive-ground
automotive equipment.

Advanced design, quality, and sturdy construction of the
Model 1686 assures continued reliability. To gain the most
effective use of this instrument, we recommend that you study
the entire manual before operating the power supply.

6

OUTPUT VOLTAGE

3 to 14 VDC, ADJUSTABLE

OUTPUT CURRENT

PROPORTIONAL TO OUTPUT VOLTAGE;

3V

2.5A

5V

4.5A

9V

7.5A

12V

10.0A

13.8V

12.0A

14V

12.0A

LOAD REGULATION

(0 to Rated Current) ≤ 0.8%

LINE REGULATION

(108–132 VAC) ≤ 0.8%

RIPPLE & NOISE ≤ 10 mV rms

PROTECTION

Current Limiting (Foldback), Reverse Polarity, Overvoltage, Short

Circuit.

METERING

Voltmeter

Range Accuracy
0 to 20V ± 7% F.S.

Ammeter

Range Accuracy
0 to 20A ± 7% F.S.

AC Input

115/230 VAC ±10%, 50/60Hz.

POWER CONSUMPTION

400 W

TEMPERATURE RANGE & HUMIDITY

Operation

0° to +40°C ≤ 85% R.H.

Storage

–15° to +70°C ≤ 75% R.H.

DIMENSIONS (H×W×D)

4.9 × 8.5 × 11.5’’ (124 × 216 × 292mm)

WEIGHT

12.1 lb. (5.45 kg)

ACCESSORIES SUPPLIED

Instruction Manual

Spare Fuse

NOTE: Specifications and information are subject to change
without notice. Please visit www.bkprecision.com for the most
current product information.

SPECIFICATIONS