Tektronix ps280, ps283 schematic
TEK
Part No. 070-8356-00
Product Group 3M
&
PS283
WARNING
The following servicing instructions
are for use by qualified service
personnel only. To avoid personal
injury, do not perform any servicing
unless you are qualified to do so.
Refer to the Safety Summary prior
to performing any service.
Please check for CHANGE INFORMATION
at the rear of this manual.
I
LABORATORY DC
POWER SUPPLY
Service Reference
First Printing JUL 1991
Revised AUG 1991
Tektronix
COMMTTCD
TO
EXEa_LB\CE
Copyright©
publication may not be reproduced in any form without the written
permission of Tektronix, Inc.
1991
Tektronix, Inc. All rights
reserved.
Contents of this
Products of
and foreign patents issued and pending.
TEKTRONIX, TEK, SCOPE-MOBILE, and W2S are registered
trademarks of Tektronix, Inc.
Printed in
reserved.
Tektronix,
U.S.A.
Inc., and its subsidiaries are covered by U.S.
Specification and price change privileges are
INSTRUMENT SERIAL NUMBERS
Each instrument
stamped on the chassis. The first two digits designate the country of
manufacture. The last five digits
each instrument. The country of manufacture is identified as follows:
B000000 Tektronix, Inc., Beaverton, Oregon,
E200000 Tektronix United Kingdom, Ltd., Marlow
has a
serial number
of
the serial number are unique
on a
panel insert,
U.S.A.
tag, or
to
G100000 Tektronix Guernsey, Ltd., Channel Islands
HKOOOOO Hong Kong
H700000 Tektronix Holland, NV, Heerenveen,
The Netherlands
JPOOOOO Sony/Tektronix, Japan
TWOOOOO Taiwan
WBWtfitiAnnnrinn contents
Specifications
Operating Information
Operators and Service Safety Summary
Symbols and Terms
Specific Precautions
Product Description
General
Specifications
General Operating Instructions
Front Panel
Rear Panel
- -|_i
2-1
The Variable Power Supplies
The Fixed Voltage Power Supply
2-4
xi
xii
1.1
1_2
2-1
2-2
X
2-3
i
Theory
of
Operation
Theory
of
Operation
General
Circuit Description
3.1
Master Voltage Output
Slave Voltage Output
5 V Fixed Voltage Output
3.1
3-1
3-1
3-2
3-4
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
REV AUG 1991
Performance Verification
Adjustment
Preparation 4-1
Requirements for Performance 4-1
Warm-up Period 4-1
Access 4-1
Test Equipment 4-1
Equipment Required 4-2
Performance Tests 4-3
Constant Current Load Regulation 4-3
Constant Current Ripple and Noise 4-5
Constant Voltage Regulation 4-7
Preparation 5-1
Requirements for Performance 5-1
Personnel 5-1
Warm-up Period 5-1
Access 5-1
Test Equipment 5-1
Maintenance
Adjustment Procedures 5-3
Independent Mode 5-3
Series Tracking Mode . «. 5-5
Parallel Tracking Mode 5-6
5 V Fixed 5-7
Information 6-1
Helpful Procedures 6-1
Preventing ESD 6-1
Inspection and Cleaning 6-5
General Care 6-5
Inspection and Cleaning Procedures 6-5
Inspect Exterior 6-5
Cleaning Procedure - Exterior 6-6
Inspect Interior 6-6
Cleaning Procedure — Interior 6-7
Lubrication 6-8
REV AUG
1991
Contents
Options
Removal and Installation Procedures 6-9
Preparation - Please Read 6-9
List of Modules 6-9
General Instructions 6-10
Top Cover Removal 6-10
Slave Circuit Board Removal 6-12
Fuse Circuit Board Removal 6-13
AC Selector Circuit Board Removal 6-14
Master Circuit Board Removal 6-16
Front Panel Display Circuit Boards Assembly Removal 6-17
Front Panel Controls Circuit Board Removal 6-19
Output Connectors Circuit Board Removal 6-21
Power Transistor Circuit Boards Removal 6-23
Options and Accessories 7-1
Power Cord Options 7-1
Standard Accessories 7-1
Optional Accessories 7-1
Parts List
Diagrams
Index
Parts List 8-1
Parts Ordering Information 8-1
Module Replacement 8-1
Using the Parts List 8-2
Item Names 8-2
Indentation System 8-2
Abbreviations 8-2
Diagrams and Circuit Board Illustrations 9.1
Component Values g_1
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
REVAUG 1991
WM§$XfX¥\rUlJ List of Illustrations
Figure
2-1:
PS280 or PS283 Front Panel 2-1
Figure 2-2: Variable Power Supply Controls 2-2
Figure 2-3: Fixed Power Supply Controls 2-3
Figure 2-4: PS280 or PS283 Rear Panel 2-4
Figure
3-1:
PS280 or PS283 Variable Outputs Block Diagram 3-3
Figure 3-2: PS280 or PS283 5 V Block Diagram 3-4
Figure
4-1:
Constant Current Test Setup 4-3
Figure 4-2: Constant Current Ripple and Noise Test Setup 4-5
Figure 4-3: Constant Voltage Test Setup 4-7
Figure
5-1:
Master Circuit Board Adjustment Locations 5-8
Figure 5-2: Display Assembly Circuit Board Adjustment Locations ... 5-9
Figure 5-3: Front Panel Controls Circuit Board Adjustment Locations . 5-9
Figure
6-1:
Top Cover Removal 6-11
Figure 6-2: Slave and Fuse Circuit Board Removal 6-13
Figure 6r3: AC Selector and Master Circuit Board Removal 6-15
Figure 6^4: Front Panel Display Assembly Removal 6-18
Figure 6-5: Front Panel Controls Assembly 6-20
Figure 6-6: Output Connectors Circuit Board
and Power Switch Location 6-22
Figure 6-7: Power Transistor Circuit Boards Location 6-23
PS280 & PS283
Laboratory
DC
Power Supply
Figure
8-1:
Exploded View A 8-8
Figure 8-2: Exploded View B 8-16
Module-Level Service Manual REV AUG 1991
vii
WMMfflfWinnnnj ust
Table 1-1: Operational Characteristics 1-2
Table 1-2: Physical Characteristics 1.3
Table 1-3: Environmental Characteristics 1-3
Table 1-4: Electrical Characteristics 1-3
Table
4-1:
Test Equipment 4-2
Table 4-2: Load Resistor Values for Current Checks 4-4
Table 4-3: Load Resistor Values for Ripple Checks 4-6
Table 4-4: Load Resistor Values for Voltage Checks 4-8
Table
6-1:
Relative Susceptibility to Static-Discharge Damage 6-3
Table 6-2: External Inspection Check List 6-6
Table 6-3: Internal Inspection Check List 6-7
Table 6-4: Tools Required for Module Removal 6-10
of Tables
PS280 & PS2S3 Laboratory DC Power Supply Module-Level Service Manual ;
x
Operators and Service Safety Summary
Please take a moment to review these safety precautions. They are provided
for your protection and to prevent damage to the power supply. This safety
information applies to all operators and service personnel.
Symbols and Terms
These two terms
• l^°!L\ statements identify conditions or practices that could result in
damage to the equipment or other property.
ttwwws
•
I
personal injury or loss of life.
These two terms appear on equipment:
•
CAUTION
one reads the marking, or a hazard to property including the equipment
•
DANGER
reads the marking.
This symbol appears in manuals:
appear
* statements identify conditions or practices that could result in
indicates a personal injury hazard not immediately accessible as
indicates a personal injury hazard immediately accessible as one
in
manuals:
®
Static-Sensitive Devices
These symbols appear on equipment:
DANGER
High Voltage
PS280 & F32S3 Laboratory DC Power Supply Module-Level Service Manual xl
Protective
ground (earth)
terminal
ATTENTION
manual
Specific Precautions
Observe all of the following precautions to ensure your personal safety and to
prevent damage to either the PS280 or PS283Laboratory DC Power Supply or
equipment connected to it.
Do Not Perform Service While Alone
Do not perform internal service or adjustment of this product unless another
person capable of rendering first aid and resuscitation is present.
Use Care When Servicing With Power On
Dangerous voltages exist at several points in this product. To avoid personal
injury, do not touch exposed connections or components while power is on.
Disconnect power before removing protective panels, soldering, or replacing
components.
Power Source
The PS280 or PS283 Laboratory DC Power Supply is intended to operate from
a power source that will not apply more than 250 V rms between the supply
conductors or between either supply conductor and ground. A protective
ground connection, through the grounding conductor in the power
essential for safe system operation.
cord,
is
Grounding the power supply
The PS280 or PS283 Laboratory DC Power Supply is grounded through the
power
cord.
To avoid electric shock, plug the power cord into a properly wired
receptacle where earth ground has been verified by a qualified service person.
Do this before making connections to the output terminals of the Laboratory DC
Power Supply. -
Without the protective ground connection, all parts of the PS280 or PS283
Laboratory DC Power Supply are potential shock hazards. This includes knobs
and controls that may appear to be insulators.
Use the Proper Power Cord
Use only the power cord and connector specified for your product. Use only a
power cord that is in good condition.
Use the Proper Fuse
To avoid fire hazard, use only the fuse specified in the parts list for your
uct, and which is identical in type, voltage rating, and current rating.
prod-
REV AUG 1991
Operators and Service Safety Summary
Do Not Remove Covers or Panels
To avoid personal injury, do not operate the PS280 or PS283 Laboratory DC
Power Supply without the panels or covers.
Do Not Operate in Explosive Atmospheres
ThePS280 or PS283 Laboratory DC Power Supply provides no explosion
protection from static discharges or arcing components. Do not operate in an
atmosphere of explosive gasses.
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
xll!
BmMfJWnr Specifications
#%f%M_rLTLn Product Description
This subsection begins with a general description of the PS280 or PS283
Power Supply. The Specifications subsection immediately follows.
General
The Tektronix PS280 or PS283 Laboratory DC Power Supply is a multifunction
bench or portable instrument. This regulated power supply provides a fixed 5 V
output for powering logic circuits and two variable outputs for a wide variety of
test and experimental uses. The PS280 or PS283 can be used in any application where three independent power supplies housed in a single package
represent a convenience.
The PS280 or PS283 contains two identical, independently adjustable DC
power supplies that you can vary from 0 to 30
variable power supplies varies from 0 to 2 A. The current on the PS283
able power supplies varies from 0 to 1 A. In all other respects the instruments
are identical. Unless otherwise noted, descriptions and procedures in this
manual apply to both instruments.
Front panel switches select one of three modes of operation: independent,
series, or parallel. In the independent mode, the output voltage and current of
each supply can be controlled independently. In the two tracking modes, the
variable outputs are connected either in series or in parallel. Under these
circumstances, the controls of the master power supply adjust the voltages or
current of both power supplies. Series mode allows the power supplies to be
varied from 0 to 60 V at 0 to 2 A for the PS280, or 0 to 1 A for the PS283.
Parallel mode allows the power supplies to be varied from 0 to 4 A for the
PS280 at 0 to 30
V,
or from 0 to 2 A at 0 to 30 V for the PS283.
V.
The current on the PS280
vari-
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
REV
AUG 1991
f-f
Product Description
Specifications
Table 1-1: Operational Characteristics
Characteristic
Outputs
Voltage (5 V)
Voltage (0-30 V)
Line regulation (5 V)
Line regulation (CV)
Line regulation (CC)
Load regulation (5 V)
Load regulation (CV)
Load regulation (CC)
Ripple/noise (5 V)
Ripple/noise (CV)
Ripple (CC)
Measurement
Two 0 to 30
5.0 ±0.25 VDC at 3.0 A maximum foldback current limited
0-30 constant VDC at 2.0 constant A maximum (PS280) or 1.0
constant A maximum (PS283)
<5mV
<0.01%
<0.01%
<0.2%
<0.2%
<0.01 % + 3 mV (rating current <3 A)
<0.01 % +5 mV (rating current >3 A) PS280
<300 mV (0-60 V single series tracking supply)
<0.2%
<2 mV rms
<1 mV
<3 mA rms
VDC,
one 5 VDC
+3mVPS280
+ 5 mV PS283
+3mA
+3mA
rms,
5 Hz-1 MHz
Temperature coefficient (CV)
Recovery time (CV)
Tracking error (slave)
Indicator
Meter indicators
Insulation (chassis to terminals)
Insulation (chassis to AC cord)
<300 ppm/ °C
<100 p.s (time to recover after a 50% load change with 0.5 A
minimum)
<0.5%
-f-10 mV of the master supply
Two 31/2 digits 0.5 in. LED panel display meter
0-30 VDC ±(0.5% of RDG + 2 digits)
0-2 A ±(0.5% of RDG + 2 digits)
>20 MH at DC 500 V
>30 MXl at DC 500 V
REVAUG 1991
Specifications
Table 1-2: Physical Characteristics
Product Description
Dimension
Width
Height
Depth
Weight
Characteristic
Storage
Operating
Characteristic
Line voltage
Power consumption
Measurement
255 mm (10.0 in)
145 mm (5.7 in)
335 mm (13.2 in)
11.5 kg (25.4 Ib) PS280 9.0 kg (19.9 Ib) PS283
Table 1-3: Environmental Characteristics
Temperature Relative Humidity
-10°Cto+70°C 70%
0°C to 40 °C 80%
Table 1-4: Electrical Characteristics
Measurement
90 to 110
108 to 132
198 to 242
216 to 250, all VAC at 50-60 Hz
348 VA, 250 W maximum (PS280)
254 VA, 172 W maximum (PS283)
PS2S0 & P5283 Laboratory DC Power Supply Module-Level Service Manual
REV AUG
1991
IHF LTOperating Information
WWXtX General Operating Instructions
Front Panel
This section describes the controls on the front and rear panels of the PS280
or PS283 Laboratory DC Power Supply.
Figure
2-1
shows the front panel of the instrument.
LABORATORY
1.
The power switch turns on the instrument when pressed. When you press
it again, the instrument is turned off.
DC POWER SUPPLY
Figure
2-1:
PS280 or PS283 Front Panel
//// TWCmniX
PS 280
CC POWER
SUPPLY/
2.
The switches labeled TRACKING determine the test mode of the instru-
ment. The PS280 or PS283 features two tracking modes: series and
parallel.
able power supplies operate independently. If the left switch is pushed in,
the instrument operates in series mode. If both switches are pushed in, the
instrument operates in parallel mode.
In series mode, the master power supply controls the voltage for both
power supplies, which can then range from 0 to 60 V.
In parallel mode, the master power supply controls both the voltage and
the current for both power supplies. The current can then range from 0 to
4A(0to2AforthePS283).
PS2S0 & PS283 Laboratory DC Power Supply Module-Level Service Manual
If both push-button switches are disengaged (out), the two
REV AUG
vari-
1991
General Operating Instructions
3. These controls affect the right variable power supply. If the instrument is in
a tracking mode, the right power supply is the master. In a tracking mode,
either or both of the control knobs can affect both variable power supplies.
4.
These controls affect the left variable power supply. If the instrument is in a
tracking mode, the left power supply is the slave. In a tracking mode,
either or both of the control knobs have no effect.
5. These controls affect the fixed 5 V power supply.
The Variable Power Supplies
Figure 2-2 shows the controls for the master variable power supply.
CURRENT
VOLTAGE
Figure 2-2: Variable Power Supply Controls
1.
The output terminals for the power supply allow you to plug in the test
leads.
The red one on the right is the positive polarity output terminal. It is
indicated by a + sign above it.
The black one on the left is the negative polarity output terminal. It is
indicated by a - sign above it.
The green one in the middle is the earth and chassis ground.
2.
The voltage control knob allows you to set the output voltage for the
power supply.
REV AUG
1991
3. The current control knob allows you to set the output current for the power
supply.
4.
If the C.V. light is lighted, the power supply is producing a constant volt-
age.
If the C.C. light is lighted, the power supply is producing a constant
current.
Operating Information
General Operating Instructions
5. The LED display lights when the instrument is turned on. The numbers
indicate the voltage or current produced by the variable power supply.
6. The AMPS/VOLTS meter selection switch determines whether the LED
display shows the current or the voltage. If the switch is pushed to the left,
the display shows the current. If the switch is pushed to the right, the
display shows the voltage.
The meter selection switch is to the right of the corresponding display for the
slave variable power supply. All other controls are the same for both variable
power supplies.
The Fixed Voltage Power Supply
Figure 2-3 shows the controls for the fixed voltage power supply.
5V FIXED 3A
Figure 2-3: Fixed Power Supply Controls
1.
The output terminals for the power supply allow you to plug in the test
leads.
The red one on the right is the positive polarity output terminal. The
black one on the left is the negative polarity output terminal.
2.
The overload indicator lights when the current on the 5 V power supply
becomes too large.
PS280 & PS2S3 Laboratory DC Power Supply Module-Level Service Manual
REV
AUG 1991
2-3
General Operating Instructions
Rear Panel
Figure
2-4
shows the rear panel
of
the instrument.
Figure 2-4: PS280
1.
These two switches allow you
voltage. Push the top switch
100
to
120
V;
push
it to
the right
•gggss
1
^
S
TEOTRONKINC,
BEAVEHTON.,OH,U.SA
1UKXTAIWAMJI.0.C
or
PS283 Rear Panel
to
set the instrument for the correct line
to
the left
if
the line voltage
If
the line voltage
is in
^
A©
s
is in
the range
y
the range
of
220
of
to
The bottom switch determines whether the line voltage
high end
the low end
voltage
2.
This
holder to ensure that you are using the correct fuse. This
change the fuse.
3. This
of
the voltage range. Push
of
the range-100
is at
the high end
is
the fuse holder. Pull the middle tab down and out
is
the receptacle for the power
of
the
or
220
range
it to
V;
-120
cord.
the left
push
or
it to
is
In the low or the
if
your line voltage
the right
240 V.
if
to
open the fuse
is
also how you
is at
your line
Operating Information
BBSftXfTTheory of Operation
WMSPXfXVtTirL
Theory
of Operation
General
Circuit Description
The PS280 or PS283 Laboratory DC Power Supply consists of two variable
output supplies and one 5 V fixed output. The circuit elements and their func-
tions are described in the Circuit Description, using the Block Diagram as an
aid in following the circuit description.
The detailed circuit description uses the block diagram, Figure
for the circuit description. The Block Diagram contains both the circuit component reference designators and lists the appropriate schematic on which they
can be found.
3-1
as a guide
Master Voltage Output
Single phase input power is applied to transformer
The outputs from transformer
relays
RL101
required from the Series Regulator by providing varying voltages to the Main
Rectifier circuit, depending on the output requirements.
The Main Rectifier circuit consists of diodes D1011 through D1014 that form a
full wave bridge rectifier. The output from the bridge rectifier is filtered by
capacitor
circuit.
and RL102. The relay control circuit limits the power dissipation
C102.
The filtered output voltage is applied to the Series Regulator
TS101
are applied to the Main Rectifier circuit by
TS101
through the AC input
The Series Regulator circuit consists mainly of
a regulated voltage to the Laboratory DC Power Supply Master output.
The Auxiliary Rectifier circuit consists of diodes 01021 through D1024 that
form a full wave bridge rectifier. The bias voltage from the bridge rectifier is
filtered by capacitors C103 and C104. This bias voltage is then applied to the
Reference Voltage circuit.
The Reference Voltage circuit consists of
ence circuit provides a regulated +15 V and -15 V to be used by the Current
Comparator circuit and the Reference Voltage Amplifier circuit.
The Current Comparator circuit, consisting of U105, limits the output current of
the Series Regulator circuit through OR gate and Amplifier circuit consisting of
D107,
and Q103 and Q104. Master CURRENT control, VR105, sets the maxi-
mum output current level.
P3280 & PS263 Laboratory DC Power Supply Module-Level Service Manual
U101,
Q1071
Q101,
REV AUG
and
R1261,
and Q102. This Refer-
1991
that deliver
Theory of Operation
The Reference Voltage Amplifier circuit consists mainly of U103, and the
Voltage Comparator circuit consists mainly of U104. U104 compares the
voltage from the Reference Voltage Amplifier with feedback from the output
voltage and, through diode D105 and the amplifier circuit of Q103 and Q104,
provides a calibrated output voltage.
The Tracking Selector switches (S501A and S501B), along with the Tracking
Delay circuit (U501 and U502), Relay Control circuit
and the Tracking Relays
(RL501,
RL502, and RL503) set the configuration of
(Q501,
Q502, and Q503),
the Master and Slave outputs.
The TRACKING Mode Switches set the Laboratory DC Power Supply in one of
three modes: INDEPendent Mode, SERIES tracking mode, or PARALLEL
mode.
The on/off conditions of relays
RL501,
RL502, and RL503 are shown
below, according to the operating mode selected.
Tracking Operation
Series Tracking
Parallel Tracking
Independent O/P
Off
On
Off
On
On
Off
Off
On
Off
When in the SERIES Tracking mode, The Master negative output is shorted to
the Slave positive output. Also, the Master output voltage provides the voltage
reference for the Reference Voltage Amplifier circuit, U303.
When in the PARALLEL Tracking mode, both the negative and positive outputs
from the Master outputs are shorted to the negative and positive outputs of the
Slave outputs. A reference voltage for Current Comparator U305 is provided
through R1261 from the Master supply circuit.
U501 and U502 are used to protect the Laboratory DC Power Supply from
instant high voltage/current during the switching time of the relay contacts.
Slave Voltage Output
The Slave output circuitry performs the same as described for the Master
Voltage output. The circuits are the same except for the component names.
Refer to the block diagram for appropriate component names of the Slave
output circuit.
REV
3-2
AUG1991
Theory of Operation
AC Input
Theory
of
Operation
Reference
Voltage Source
<2>
Current Comparator
Reference Voltage
Amplifier
Tracking Selector
Auxiliary Rectifier
and Filter
D1021-D1024
C103-C104
D105,
D107
Voltage Comparator
Tracking Delay
U501-U502
u
Transformer
O
Amplifier
Q103-Q104
Relay Control
Q501-Q503
Relay Control
RL101-RL102
JJ
Main Rectifier and Filter
D1011-D1014
u
Series Regulator
Q1071.R1261
Tracking
O/P Control
RL501-RL503
Master Output
Reference
Voltage Source
Current Comparator
Reference Voltage
Amplifier
Figure
Auxiliary Rectifier
and Filter
D3021-D3024
C303-C304
Main Rectifier and Filter
0302.
D307
Amplifier
Q303-Q304
'
A """"A
Voltage Comparator
3-1:
PS280 or PS283 Variable Outputs Block Diagram
3_JJ.
<3>
Relay Control
RL301-RL302
u
D3011-D3014
Series Regulator
Q3071.
R3261
Slave Output
P3280 & PS283 Laboratory
uu
power supply Module-Level Service Manual
REV
AUG
1991
Theory of Operation
5 V Fixed Voltage Output
AC Input
u\
Transformer
•
Current Comparator
The 12 V output from transformer
The Rectifier circuit consists of diodes D4011 through D4014 that form a full
wave bridge rectifier. The output from the bridge rectifier is filtered by capacitor
C401.
The filtered output voltage is applied to the Series Regulator circuit.
The Series Regulator circuit consists mainly of Q402 and R407, that deliver a
regulated voltage to the Laboratory DC Power Supply 5 V Fixed output.
The Current Comparator circuit, consisting of
the Series Regulator circuit through Q401.
Rectifier and Filter
D4011-D4014
<>
Series Regulator
andC401
Q402,
R407
TS101
is applied to the Rectifier circuit.
U401,
limits the output current of
5 V Fixed
Output
>
<2>
Figure 3-2: PS280 or PS283 5 V Block Diagram
REVAUG 1991
Theory of Operation
SIB Performance Verification
WMiMrWinnnnTL Preparation
Purpose - Use this procedure to verify that the Laboratory DC Power Supply
is in conformance with its specifications as listed in Section 1, Specifications.
It can also be used for incoming inspection of the Laboratory DC Power
Supply.
Performance Verification Interval
performed whenever the accuracy or functions of the power supply are
question.
performing the adjustments in Section 5, Adjustments.
Requirements
Performance address the following requirements.
for
Before you perform these performance verification procedures, you need to
Warm-up Period
The Laboratory DC Power Supply requires a 20 minute warm-up time in
20°C to 30°C environment before a performance verification
A performance verification should be used to verify the need for
Access
Cabinet removal is not required to perform any of these procedures
Test Equipment
Table
4-1
lists all the test equipment required to perform both the Performance
Verification procedures and the Adjustment Procedures for the PS280
Laboratory DC Power Supply.
-A
performance verification should be
is
made.
in
a
or
PS283
PS2S0 & P32S3 Laboratory DC rower supply Module-Level Service Manual
REV
AUG 1991
4.7
Preparation
Equipment Required
Item Number and
Description
1 Adjustment Tool
2 Multimeter, Digital
3 Resistive Load,
Vari-
4 Oscilloscope
5 Fixed Resistive
Loads Set
Minimum Requirements
Less than % inch
diameter and over 2
inches long
35
Accuracy
0 to 2 n, 30 Watts
50 MHz, 3% vertical
deflection accuracy
20 a, 30 Watts
10 a, 30 Watts
2 fl, 5 Watts
1 a, 30 Watts
7 a, 140 Watts
0.5 a, 5 Watts
15X1,70 Watts
30 a, 140 Watts
7.511,140
1.7 n, 20 Watts
30 a, 40 Watts
60 a, 70 Watts
The test equipment required for both the performance verification procedures
and the adjustment procedures for the Laboratory DC Power Supply are listed
Table
4-1:
Test
Equipment
Example
Tektronix part number
Purpose
Adjustments
003-0675-00
V,
4 A, ±0.1%
TEKTRONIX DM252
Tektronix part number
Adjustments
Adjustments
311-2494-00
TEKTRONIX 2225
Tektronix part number
Performance Verification
Performance Verification
118-8751-00
Watts
6 Mechanical Switch 60 Watts
REV
AUG
1991
Tektronix part number
260-2570-00
Performance Verification
Performance Verification
WMMPXfXlftnnr
Performance Tests
Constant Current
Load Regulation
Equipment Required: Digital multimeter and load resistors
Figure
4-1:
Constant Current Test Setup
1.
Check the Master current regulation
a. Set up the equipment:
• Disengage both TRACKING mode switches (both switches out) so
that the power supply is in the INDEPendent operating mode.
(INDEPendent
mode):
•*-i
RL1
• Set the Master AMPS/VOLTS meter selection switch to AMPS.
• Set the digital multimeter to measure a DC voltage of +
• Connect the digital multimeter to the + and - terminals of the
MASTER output.
• Set the Laboratory DC Power Supply MASTER VOLTAGE control
until the multimeter reads +25 V.
• Disconnect the multimeter from the power supply.
• Set the digital multimeter to measure a DC current of at least 1
amp (PS280) or 0.5 amps (PS283).
• Connect the multimeter, load resistors, and test switch to the
+ and - terminals of the Master output as indicated in Figure
See Table 4-2 for the appropriate values of the load resistors.
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
REV AUG
1991
25
volts.
4-1.
Performance Tests
b.
Verify
the current regulation:
• Check that the output current level changes less than 0.2%
±3 mA while switching load resistor
Table 4-2: Load Resistor Values for Current Checks
RL1
in and out of the circuit
PS280
oae
M
INDEP
PARALLEL
2.
Check the Slave current regulation
a. Set up the equipment:
• Set the Slave AMPS/VOLTS meter selection switch to AMPS.
• Set the digital multimeter to measure a DC voltage of + 25 volts.
• Connect the digital multimeter to the + and - terminals of the
Slave output.
• Set the Laboratory DC Power Supply SLAVE VOLTAGE control
until the multimeter reads +25 V.
• 'Disconnect the multimeter from the power supply.
• Set the digital multimeter to measure a DC current of at least 1
amp (PS280) or 0.5 amps (PS283).
a Connect the multimeter, load resistors, and test switch to the
+ and - terminals of the Slave output as indicated in Figure
See Table 4^2 for the appropriate values of the load resistors.
RL1
20
D.,
30
10 a, 30
W
w
RL2
,5W
2O
,30W
in
(INDEPendent
20
10
RL1
a 30
a
so
mode):
PS283
W
w
RL2
2fl.5W
1
a
30
w
4-1.
REV AUG
1991
b.
Verify
3. Check the Master current regulation
a. Set up the equipment:
the current regulation:
• Check that the output current level changes less than 0.2%
±3 mA while switching load resistor
• Engage both TRACKING mode switches (both switches in) so that
the power supply is in the PARALLEL operating mode.
• Set the digital multimeter to measure a DC voltage of +
• Connect the digital multimeter to the + and - terminals of the
MASTER output.
• Set the Laboratory DC Power Supply MASTER VOLTAGE control
until the multimeter reads +25 V.
• Disconnect the multimeter from the power supply.
RL1
(PARALLEL
in and out of the circuit
mode):
25
volts.
Performance Verification
Performance Tests
• Set the digital multimeter to measure a DC current of at least
1 amp (PS280) or 0.5 amps (PS283).
• Connect the multimeter, load resistors, and test switch to the
+ and - terminals of the Master output as indicated in Figure
See Table 4-2 for the appropriate values of the load resistors.
b.
Verify
the current regulation:
• Check that the output current level changes less than 0.2%
±5 mA while switching load resistor
RL1
in and out of the circuit
4-1.
Constant Current
Ripple and Noise
Equipment Required: Oscilloscope and load resistors
Figure 4-2: Constant Current Ripple and Noise Test Setup
1.
Check the Master current ripple:
a. Set up the equipment:
• Disengage both TRACKING mode switches (both switches out) so
that the power supply is in the INDEPendent operating mode.
• Set the Master AMPS/VOLTS meter selection switch to VOLTS.
• Set the Laboratory DC Power Supply to+25 volts (using the
digital display).
• Connect the test oscilloscope and load resistors to the + and terminals of the Master output as indicated in Figure 4-2. See
Table 4-3 for the appropriate values of the load resistors.
b.
Verify
PS280 & PS283 Laboratory DC Power Supply Module-Level Service Manual
the current ripple:
• Check that the peak-to-peak ripple viewed with the test oscilloscope is less than 2.5 mV.
REV AUG 1991
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