B+K precision 1673 User manual

Model 1672, 1673
Triple Output Power Supply
INSTRUCTION MANUAL

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1 Safety Summary
The following safety precautions apply to both operating and maintenance personnel and
must be observed during all phases of operation, service, and repair of this instrument.
Before applying power, follow the installation instructions and become familiar with the
operating instructions for this instrument.
GROUND THE INSTRUMENT
To minimize shock hazard, the instrument chassis and cabinet must be
connected to an electrical ground. This instrument is grounded through the
ground conductor of the supplied, three-conductor ac power cable. The power
cable must be plugged into an approved three-conductor electrical outlet. Do not
alter the ground connection. Without the protective ground connection, all
accessible conductive parts (including control knobs) can render an electric
shock. The power jack and mating plug of the power cable meet IEC safety
standards.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE
Do not operate the instrument in the presence of flammable gases or fumes.
Operation of any electrical instrument in such an environment constitutes a
definite safety hazard.
KEEP AWAY FROM LIVE CIRCUITS
Instrument covers must not be removed by operating personnel. Component
replacement and internal adjustments must be made by qualified maintenance
personnel. Disconnect the power cord before removing the instrument covers
and replacing components. Under certain conditions, even with the power cable
removed, dangerous voltages may exist. To avoid injuries, always disconnect
power and discharge circuits before touching them.
DO NOT SERVICE OR ADJUST ALONE
Do not attempt any internal service or adjustment unless another person,
capable of rendering first aid and resuscitation, is present.
DO NOT SUBSTITUTE PARTS OR MODIFY THE INSTRUMENT
Do not install substitute parts or perform any unauthorized modifications to this
instrument. Return the instrument to B&K Precision for service and repair to
ensure that safety features are maintained.

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WARNINGS AND CAUTIONS
WARNING and CAUTION statements, such as the following examples, denote a
hazard and appear throughout this manual. Follow all instructions contained in
these statements.
A WARNING statement calls attention to an operating procedure, practice, or
condition, which, if not followed correctly, could result in injury or death to
personnel.
A CAUTION statement calls attention to an operating procedure, practice, or
condition, which, if not followed correctly, could result in damage to or
destruction of parts or the entire product.
WARNING:
Do not alter the ground connection. Without the protective
ground connection, all accessible conductive parts (including
control knobs) can render an e
lectric shock. The power jack and
mating plug of the power cable meet IEC safety standards.
WARNING:
To avoid electrical shock hazard, disconnect power cord before
removing covers. Refer servicing to qualified personnel.
CAUTION:
Before connecting th
e line cord to the AC mains, check the rear
panel AC line voltage indicator. Applying a line voltage other
than the indicated voltage can destroy the AC line fuses. For
continued fire protection, replace fuses only with those of the
specified voltage and current ratings.
CAUTION:
This product uses components which can be damaged by electro
-
static discharge (ESD). To avoid damage, be sure to follow
proper procedures for handling, storing and transporting parts
and subassemblies which contain ESD-sensitive components.
SAFETY SYMBOL
This symbol on an instrument indicates that the user should refer to the
operating instructions located in the manual.
Electrical shock hazard.
Chassis ground symbol.

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Compliance Statements
Disposal of Old Electrical & Electronic Equipment (Applicable in the European
Union and other European countries with separate collection systems)
This product is subject to Directive 2002/96/EC of the
European Parliament and the Council of the European
Union on waste electrical and electronic equipment
(WEEE), and in jurisdictions adopting that Directive, is
marked as being put on the market after August 13, 2005,
and should not be disposed of as unsorted municipal
waste. Please utilize your local WEEE collection facilities
in the disposition of this product and otherwise observe
all applicable requirements.

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Table of Contents
1Safety Summary..........................................................................................................................1
2Introduction .................................................................................................................................5
3Installation....................................................................................................................................5
3.1 Initial Inspection..............................................................................................................5
3.2 Input Power Requirements.........................................................................................6
3.3 Location ...............................................................................................................................6
4Controls and Indicators...........................................................................................................7
4.1 Front Panel.........................................................................................................................7
4.2 Rear Panel...........................................................................................................................8
5Operating Instructions ............................................................................................................9
5.1 Setting the Output Voltage and Output Current ................................................9
5.2 Constant Voltage (CV) /Constant Current (CC) Mode.....................................9
5.3 System Configuration .................................................................................................10
5.3.1 Independent Mode............................................................................................10
5.3.2 Series Tracking Mode ......................................................................................10
5.3.3 Parallel Tracking Mode ...................................................................................11
5.3.4 Multiple Units in Series Mode ......................................................................12
5.3.5 Multiple Units in Parallel Mode...................................................................13
5.3.6 Fixed 5V/3A Output .........................................................................................14
6Specifications............................................................................................................................15
7Maintenance..............................................................................................................................16
7.1 Preventive Steps ...........................................................................................................16
7.2 When the Unit is Not Turning On..........................................................................17
7.3 Fuse Replacement ........................................................................................................17
8Service Information ...............................................................................................................18
9Limited Two-Year Warranty..............................................................................................19

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2 Introduction
Description
B&K Precision’s 1672 and 1673 triple output DC power supplies provide two variable
outputs (0 – 32V/ 0 – 3A [model 1672], 0-6A [model 1673]) and one fixed output (5V/3A).
The variable outputs can work independently, in series tracking, or parallel mode.
Conveniently adjust voltage and current with independent front panel knobs and bright
quad display. These power supplies are ideally suited for applications in electronic test,
production, and service, where multiple independent DC power supplies are required and
bench space is at a premium.
Features
•Three independent outputs
•Individual control of voltage and current controls for variable outputs
•CV (constant voltage)/CC (constant current) mode operation
•Separate 3-digit displays for voltage and current for variable outputs
•LED indication for CV/CC mode
•Overload indication LED for fixed output
•Series tracking and parallel mode operation
•Power On/Off switch on front panel
•Input voltage selection on rear side (115 Vac/ 230 Vac)
3 Installation
3.1 Initial Inspection
This unit is tested prior to shipment. It is therefore ready for immediate use upon receipt.
The initial physical inspections should be made to ensure that no damage has been
sustained during shipment.
Inspect the packing box on receipt for any external damage. If any external damage is
evident, remove the instrument and visually inspect its case and parts for any damage. If
damage to the instrument is evident, a description of the damage should be noted on the
carrier’s receipt and signed by the driver or carrier agent. Save all shipping packaging for
inspection. Forward a report of any damage to the agent through which the unit is
procured.

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Retain the original packing in case subsequent repackaging for return is required. Use of
the original packing is essential.
After the mechanical inspection, verify the contents of the shipment. The items included
with the instrument are:
•Power cord
•Instruction manual
•Pair of test leads (x2)
If the contents are incomplete, or if the instrument does not pass the specification
acceptance tests, notify the local service center.
3.2 Input Power Requirements
The instrument can operate on 115 V or 230 V AC source at 50 or 60 Hz. The line selector
plug on the rear panel allows you to select the line voltage. Before connecting the power
plug to an AC line outlet, be sure to check that voltage selector plug is set in the correct
position corresponding to the line voltage in your location and the fuse rating is as shown
in the table.
Selector Line Voltage Fuse
115V
100 ~ 125V 50/60 Hz
6A (model 1672)
10A (model 1673)
230V
220 ~ 240V 50/60 Hz
3A (model 1672)
6A (model 1673)
Figure 1 – Fuse Table
3.3 Location
Before applying power to unit, make sure that input voltage setting is correct and the
ventilation holes are not blocked. Ensure that the ventilation fan located on the rear panel
is working well (it should turn on when powered on). Do not load the output if ventilation
fan is not working otherwise it may cause the power supply to overheat.

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4 Controls and Indicators
4.1 Front Panel
Figure 2 – Front Panel
1) Power switch
2) Negative output terminal of the fixed 5V/3A output
3) Positive output terminal of the fixed 5V/3A output
4) Overload indicator LED for fixed 5V/3A output
5) Negative output terminal of the master output
6) Ground terminal of the master output
7) Positive output terminal of the master output
8) CC mode LED for the master to indicate constant current
9) CV mode LED for the master to indicate constant voltage
10) Master voltage adjustment knob with push/pull switch mechanism for series tracking
mode operation
11) Master current adjustment knob with push/pull switch mechanism for parallel mode
operation
12) Master voltage indicator display (3-digit green 0.56” LED)

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13) Master current indicator display (3-digit red 0.56” LED)
14) Series mode indicator LED
15) Parallel mode indicator LED
16) Slave voltage indicator display (3-digit green 0.56” LED)
17) Slave current indicator display (3-digit red 0.56” LED)
18) Voltage adjustment knob for adjusting slave output voltage when master power is in
CV mode
19) Current adjustment knob for adjusting slave output current when master power is in
CC mode
20) Negative output terminal of the slave output
21) Ground terminal of the slave output
22) Positive output terminal of the slave output
23) CC mode LED for the slave to indicate constant current
24) CV mode LED for the master to indicate constant voltage
4.2 Rear Panel
Figure 3 – Rear Panel
25) Heat sink for dissipating the heat of power devices
26) Fan ventilation (80mm 12V DC Fan)
27) Power input socket
28) Fuse holder and input line selector
29) Input line voltage indicator (refer to mark)

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5 Operating Instructions
5.1 Setting the Output Voltage and Output Current
1. As per load requirement, calculate the voltage and maximum current limit to be set
on output. Note: V=IR
2. Disconnect the load from output terminals.
3. For current limit adjustment, turn the current adjustment knob counter-clockwise
to get minimum current output.
4 Short the circuit between the positive and negative output terminals by the
accessory leads.
5. Vary the current adjustment knob clockwise until the current displays the required
current limit. The CC LED will be lit while adjusting the current limit. Remove the
accessory lead after current limit adjustment.
6. The voltage will be displayed again and the CV LED will be lit.
7. Vary the voltage adjustment knob to get the desired output voltage on the display.
Depending on load condition, the power supply will work either in CV or in CC mode. The
automatic changeover is indicated by the CV / CC LEDs.
5.2 Constant Voltage (CV) /Constant Current (CC) Mode
The working characteristic of this power supply is called a constant voltage/constant
current automatic crossover type. This permits continuous transition from constant
current to constant voltage modes in response to the load change. The intersection of
constant voltage and constant current modes is called the crossover point. Figure 4 shows
the relationship between this crossover point and the load.
Figure 4 – CC/CV Characteristic

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For example, if the load is such that the power supply is operating in the constant voltage
mode, a regulated output voltage is provided. The output voltage remains constant as the
load increases, up until the point where the preset current limit is reached. At that point,
the output current becomes constant and the output voltage drops in proportion to
further increases in load. The crossover point is indicated by the front panel LED
indicators. The crossover point is reached when the CV indicator goes off and the CC
indicator comes on. Similarly, crossover from the constant current to the constant voltage
mode automatically occurs from a decrease in load.
5.3 System Configuration
Models 1672 and 1673 have two variable outputs, which can work independently, in
series tracking mode, or parallel mode with pull and push switch arrangements provided
by the master voltage and current control knobs. Users can also connect multiple units in
series or parallel mode to increase their voltage or current.
5.3.1 Independent Mode
Ensure the master voltage and current control knobs are in the push condition to operate
the variable outputs independently. Connect the appropriate load between the positive
and negative terminal.
5.3.2 Series Tracking Mode
In this mode, the negative output terminal of the master gets connected internally to the
positive output terminal of the slave.
1. Pull the voltage adjustment knob of the master. The green LED will light up to indicate
series tracking mode.
2. Set output voltage with the voltage adjustment knob of the master. The display of the
master shows half the voltage of the actual output available across the positive output
terminal of the master and the negative output terminal of the slave.
The output is available across the positive output terminal of the master and the negative
output terminal of the slave.

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5.3.3 Parallel Tracking Mode
In this mode, the positive output terminal of the master gets connected internally to the
positive output terminal of the slave and the negative output terminal of the master gets
connected to the negative output terminal of the slave. The output voltage will be the same
as the master set value and the output current is twice the set master output current.
1. Pull the current adjustment knob of the master. The red LED and the red CC LED of the
slave output will light up to indicate parallel tracking mode.
2. Turn both the slave voltage adjustment knob and current adjustment knob clockwise
to maximum.
3. Set the output voltage with master voltage adjustment knob. The output current will
be twice that of the set master output current.
In parallel mode of operation, connect the appropriate load between the positive terminal
and negative terminal of the slave or between the positive terminal of the master and
negative terminal of the slave.
LOAD
Figure 5 – Series Tracking Mode Load Connection

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5.3.4 Multiple Units in Series Mode
For achieving higher voltage, two or more units can be connected in series (Max 240V
only). The output voltage of the system will be the sum of all units.
1. Set the power supplies connected in series operation under series tracking mode as
described in Series Tracking mode and adjust to the same output.
2. Connect the negative of the slave output terminal of unit 1 to the positive of the
master output terminal of unit 2.
3. The output shall be available across the positive of the master terminal of unit 1 and
the negative of the slave terminal of unit 2.
LOAD
Figure 6 – Parallel Tracking Mode Load Connection

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5.3.5 Multiple Units in Parallel Mode
Two or more units can be connected in parallel to obtain a higher current output (Max
24A only).
1. Set the power supplies connected in parallel operation under parallel tracking mode as
described in parallel tracking mode and adjust all units to the same output voltage.
2. Make the parallel connection of the positive and the negative terminals of the Master
and Slave outputs for all units.
The output voltage of the system will be the same for all units. The output current of the
system will be the sum of all units.
LOAD
Unit 1
Unit 2
Figure 7 – Connecting Multiple Units in Series

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5.3.6 Fixed 5V/3A Output
This is the standard 5V/ 3A power output provided for supplying the power to TTL logic
circuits. When the load exceeds 3A, the red OVERLOAD LED will light up. The output
voltage will be lower and the power supply will be under CC mode.
LOAD
Unit 1
Unit 2
Figure 8 – Connecting Multiple Units in Parallel

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6 Specifications
1672 1673
Output Parameters
Number of Outputs
Three (two variable and one fixed)
Range
0 to 32 VDC / 0 to 3 A
(variable) and 5 V / 3 A (fixed)
0 to 32 VDC / 0 to 6 A
(variable) and 5 V / 3 A (fixed)
Constant Voltage Mode (variable outputs)
Line Regulation
<0.01% + 5 mV
Load Regulation
<0.2% + 10 mV
<0.55% + 10 mV
Ripple & Noise
<1 mVrms
<1 mVrms (master)
<4 mVrms (slave)
Constant Current Mode (variable outputs)
Line Regulation
<0.2% + 5 mA
Load Regulation
<0.2% + 8 mA
0.4% + 8 mA
Ripple & Noise
<3 mArms
Tracking Operation
Slave Tracking Error
< 0.5%+3 digits of the master
5V Fixed Output
Voltage Accuracy
5 V ± 0.25 V
Ripple & Noise
<1 mVrms
Display
Voltage
3 digits 0.56” Green LED
Current
3 digits 0.56” Red LED
Accuracy
<0.1% + 3 digits

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General
Power Requirements
115/230 V ± 10%, 50/60 Hz ± 10%
Operating Temperature
50 °F to 104 °F (10 °C to 40 °C)
Humidity
90% R.H.
Temperature Coefficient
<300PPM / C° (voltage and current)
Dimensions (W x H x D)
9” x 6.7” x 12.2” (230 x 170 x 310 mm)
Weight
12.6 lbs (5.7 kg)
19.8 lbs (9.0 kg)
Two Year Warranty
Included Accessories
Power cord, instruction manual, two pairs of test leads
Note: All specifications apply to the unit after a temperature stabilization time of 15
minutes over an ambient temperature range of 25 °C ± 5 °C.
Specifications are subject to change without notice.
To ensure the most current version of this manual, please download the current version
here: http://www.bkprecision.com/search/manual/1673
For current up-to-date product information, please visit www.bkprecision.com
7 Maintenance
7.1 Preventive Steps
Please follow these preventive steps to ensure the proper operation of your instrument.
•Never place heavy objects on the instrument.
•Never place a hot soldering iron on or near the instrument.
•Never insert wires, pins, or other metal objects into ventilation fan.
•Never move or pull the instrument with power cord or output lead. More
importantly, never move the instrument when the power cord or output lead is
connected.

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•Do not obstruct the ventilation holes in the rear panel as this will increase the
internal temperature.
•Do not operate the instrument with the cover removed unless you are a qualified
service technician.
•Clean and recalibrate the instrument on a regular basis to keep the instrument
looking nice and working well.
•Remove any dirt, dust, and grime whenever they become noticeable on the
outside cover using a soft cloth moistened with a mild cleaning solution.
7.2 When the Unit is Not Turning On
Check if the power ON/OFF switch is turned ON. Check for blown fuse. If not, then check
the power cord. Please make sure that the power cord is properly connected to the unit.
Please also check the main switch and ensure that the AC supply at your site is the same as
the one mentioned at the rear chassis of the unit.
7.3 Fuse Replacement
If the fuse blows, the LED will not light and the instrument will not operate. Replace only
with the correct value fuse. The fuse is located on the rear panel adjacent to the power
cord receptacle.
Remove the fuse holder assembly as follows:
1. Unplug the power cord from the rear of the instrument.
2. Insert a small screwdriver in the fuse holder slot (located between fuse holder and
receptacle).
When reinstalling fuse holder, be sure that the fuse is installed so that the correct line
voltage is selected.

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8 Service Information
Warranty Service: Please go to the support and service section on our website
www.bkprecision.com to obtain an RMA #. Return the product in the original packaging
with proof of purchase to the address below. Clearly state on the RMA the performance
problem and return any leads, probes, connectors and accessories that you are using with
the device.
Non-Warranty Service: Please go the support and service section on our website
www.bkprecision.com to obtain an RMA #. Return the product in the original packaging to
the address below. Clearly state on the RMA the performance problem and return any
leads, probes, connectors and accessories that you are using with the device. Customers
not on an open account must include payment in the form of a money order or credit card.
For the most current repair charges please refer to the service and support section on our
website.
Return all merchandise to B&K Precision Corp. with pre-paid shipping. The flat-rate repair
charge for Non-Warranty Service does not include return shipping. Return shipping to
locations in North America is included for Warranty Service. For overnight shipments and
non-North American shipping fees please contact B&K Precision Corp.
B&K Precision Corp.
22820 Savi Ranch Parkway
Yorba Linda, CA 92887
www.bkprecision.com
714-921-9095
Include with the returned instrument your complete return shipping address,
contact name, phone number and description of problem.