HP BENCH Series Service manual

DC POWER SUPPLY
BENCH SERIES
MODEL 6215A
OPERATING AND SERVICE MANUAL
FOR SERIALS 8G250I - 4200
For Serials Above 8G4200
Check for inclusion of
change page.
For Serials Below 8G2 501
Refer to Appendix A.
100 Locust Avenue, Berkeley Heights, New Jersey 07922
HP Part No. 06215-90001 Printed: January, 1969

TABLE OF CONTENTS
Section Page No.
I GENERAL INFORMATION 1-1
1-1 Description 1-1
1-5 Specifications 1-1
1-7 Options 1-1
1-9 Accessories 1-1
1-11 Instrument/Manual Identification 1-1
1-14 Ordering Additional Manuals 1-1
Section page No.
IV PRINCIPLES OF OPERATION (CONTINUED)
II INSTALLATION
2-1 Initial Inspection
Mechanical Check
Electrical Check
Installation Data
Location
2-11 Outline Diagram
2-13 Rack Mounting
2-15 Input Power Requirements
Connections for 230V Operation
Power Cable
2-3
2-5
2-7
2-9
2-17
2-19
2-22 Repackaging For Shipment
111 OPERATING INSTRUCTIONS
2-1
2-1
2-1
2-1
2-1
2-1
2-1
2-1
2-2
2-2
2-2
2-2
3-1
3-1
Turn-On Checkout Procedure
3-1
3-3
Operation
3-1
3-5
Constant Voltage
3-1
3-7
Changing Current Limit
3-1
3-9
Connecting Load
3-1
3-12
Operation of Supply Beyond
Rated Output
3-2
3-14
Optional Operating Modes
3-2
3-15
Series Operation
3-2
3-17
Parallel Operation
3-2
3-19
Special Operating Considerations 3-2
3-20
Pulse Loading
3-2
3-22
Output Capacitance
3-2
3-24
Reverse Current Loading
3-2
PRINCIPLES OF OPERATION
4-1
4-1
Simplified Discussion
4-1
4-5
Detailed Circuit Analysis
4-2
4-6 Feedback Loop
4-11 Series Regulator
4-13 Constant Voltage Input Circuit
4-17 Driver and Error Amplifier
4-20 Current Limiting Circuit
4-22 Reference Circuit
4-2 6 Meter Circuit
V MAINTENANCE
5-1 Introduction
5-3 Cover Removal and Replacement
5-6 General Measurement Technique
5-11 Test Equipment Required
5-13 Performance Test
5-15 Rated Output and Meter Accuracy
5-18 Load Regulation
5-20 Line Regulation
5-35 Output Impedance
5-38 Current Limit
5-40 Transient Recovery Time
5-46 Troubleshooting
5-48 Trouble Analysis
5-53 Repair and Replacement
5-55 Adjustment and Calibration
5-57 Meter Mechanical Zero
5-59 Meter Calibration
5-61 Zero Volts Output Adjustment
5-63 Output Current Limit Adjustment
VI REPLACEABLE PARTS
6-1 Introduction
6-4 Ordering Information
Reference Designators
Abbreviations
Manufacturers
6-8 Code List of Manufacturers
Parts List Table
4-2
4-2
4-2
4-3
4-3
4-3
4-3
5-1
5-1
5-1
5-1
5-2
5-3
5-3
5-3
5-3
5-6
5-7
5-7
5-8
5-8
5-11
5-13
5-13
5-13
5-13
5-13
6-1
6-1
6-1
6-2
APPENDK A
A-1

MANUAL CHANGES
DC POWER SUPPLY
Model 6215A
Manual Serial Number Prefix 8M
Make all corrections in the manual according to errata below, then check the following table for your power
supply serial number and enter any listed change (s) in the manual.
SERIAL
MAKE
CHANGES
Prefix
Number
9C 4201 - 4450 1
ALL
-
Errata
9C
4451 - up 1,2
CHANGE 1:
In replaceable parts table, make the following
change:
R12: Change to IKn. ±5% 3W, Part No. 0813-
0001.
ERRATA:
On Page 5-4, Figure 5-5, change Rl for Models
6215A and 6216A to 62.5,^..
Change Paragraph 3-18, third sentence to read as
follows:
"The output of each power supply can be set
separately."
CHANGE 2:
In replaceable parts table, make the following
change:
R28: 820^, ±5%, ^W, ($ Part No. 0686-8215.
ERRATA:
On the Title Page, change the serial number in
formation to read: "FOR SERIALS 8G2501-4200.
For Serials Below 8G2501, Refer to Appendix A."
4-27-70

TABLE OF CONTENTS (CONTINUED)
LIST OF TABLES
Table
I-I
5-1
5-2
5-3
Specifications
Test Equipment Required
Common Troubles
Reference, Bias, and Filtered DC
Troubl e s hooting
Page No.
1-2
5-2
5-9
5-10
Table
5-4
5-5
5-6
5-7
Low Output Voltage Troubleshooting
High Output Voltage Troubleshooting
Selected Semiconductor
Characteristics
Calibration Adjustment Summary-
Page No.
5-10
5-11
11
13
LIST OF ILLUSTRATIONS
Figure
1-1
2-1
2-2
2-3
3-1
4-1
5-1
5-2
DC Power Supply
Outline Diagram
Page No.
i V
2-1
Rack Kit with Three BENCH Supplies 2-1
Input Power Transformer Connections 2-2
Front Panel Controls and Indicators 3-1
Simplified Schematic 4-1
Front Panel Terminal Connections 5-1
Output Current Measurement
Technique 5-1
Figure Page No.
5-3 Differential Voltmeter Substitute
Test Setup 5-3
5-4 Output Current, Test Setup 5-3
5-5 Load Regulation, Test Setup 5-4
5-6 Ripple and Noise, Test Setup 5-5
5-7 Noise Spike Test Setup 5-6
5-8 Output Impedance, Test Setup 5-6
5-9 Transient Recovery Time, Test Setup 5-7
5-10 Transient Recovery Time, Waveforms 5-8
5-11 Servicing Printed Wiring Boards 5-12
iii

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Figure 1-1. DC Power Supply
iv

SECTION I
GENERAL INFORMATION
1-1 DESCRIPTION
1-2 This power supply, Figure 1-1. is completely
transistorized and suitable for either bench or relay
rack operation. It is a compact, regulated. Con
stant Voltage/Current Limiting supply. The output
voltage can be continuously adjusted throughout the
output voltage range. The power supply is fully pro
tected from overloads by a fixed current limit which
is set by means of an internal adjustment. The cur
rent limit circuit permits series and parallel connec
tion of two or more supplies when greater voltage or
current is desired.
1-3 Either the positive or negative output terminal
may be grounded or the power supply can be opera
ted floating at up to a maximum of 300 volts off
ground.
1-4 A single meter is used to measure either out
put voltage or output current in volts and milliamps,
respectively. The voltage or current range is selec
ted by the METER switch on the front panel.
1-5 SPECIFICATIONS
1-6 Detailed specifications for the power supply
are given in Table 1-1.
1-7 OPTIONS
1-8 Options are factory modifications of a stand
ard instrument that are requested by the customer.
The following options are available for the instru
ment covered by this manual. Where necessary, de
tailed coverage of the options is included through
out the manual.
Option No. Description
28 230Vac, 50-400Hz, Single-Phase
Output: Factory modification consists
of reconnecting the input transformer
for 230Vac operation. Refer to Section
II for further details.
1-9 ACCESSORIES
1-10 The accessories listed in the following chart
may be ordered with the power supply or separately
from your local Hewlett-Packard field sales office
(refer to list at rear of manual for addresses).
(fe Part No. Description
1452lA 3|-" High Rack Kit for mounting up to
three BENCH supplies. (Refer to Sec
tion II for details.)
14522A 7" High Rack Kit for mounting up to
six BENCH supplies. (Refer to Sec
tion II for details.)
1-11 INSTRUMENT/MANUAL IDENTIFICATION
1-12 Hewlett-Packard power supplies are identified
by a three-part serial number tag. The first part is
the power supply model number. The second part is
the serial number prefix, which consists of a num
ber-letter combination that denotes the date of a
significant design change. The number designates
the year, and the letter A through L designates the
month, January through December respectively. The
third part is the power supply serial number.
1-13 If the serial number prefix on your power sup
ply does not agree with the prefix on the title page
of this manual, change sheets are included to up
date the manual. Where applicable, backdating
information is given in an appendix at the rear of
the manual.
1-14 ORDERING ADDITIONAL MANUALS
1-15 One manual is shipped with each power sup
ply. Additional manuals may be purchased from
your local Hewlett-Packard field office (see list at
rear of this manual for addresses). Specify the
model number, serial number prefix, and ($i stock
number provided on the title page.
1-1

Table 1-1. Specifications
INPUT:
105-125Vac, single phase, 50-400Hz.
OUTPUT:
0-25Vdc, 0-400mA.
LOAD REGULATION:
Less than 0.01% plus ImV for a full load to no
load change in output current.
LINE REGULATION:
Less than 0.01% plus 4mV for any line voltage
change within the input rating.
RIPPLE AND NOISE:
Less than 200|j.Vnns/lmV p-p (dc to 20MHz).
TEMPERATURE RANGES:
Operating: 0 to 55°C. Storage: -40 to +85°C.
TEMPERATURE COEFFICIENT:
Less than 0.02% plus ImV per degree Centi
grade.
STABILITY:
Less than 0.10% plus 5mV total drift for 8 hours
after an initial warm-up time of 30 minutes at
constant ambient, constant line voltage, and
constant load.
INTERNAL IMPEDANCE AS A CONSTANT VOLT
AGE SOURCE:
Less than 0.03 ohms from dc to IkHz.
Less than 0.5 ohms from IkHz to lOOkHz.
Less than 3.0 ohms from lOOkHz to IMHz.
TRANSIENT RECOVERY TIME:
Less than 50[j.sec for output recovery to within
lOmV following a full load current change in the
output.
OVERLOAD PROTECTION:
A fixed current limiting circuit protects the
power supply for all overloads including a direct
short placed across the output terminals in con
stant voltage operation.
METER:
The front panel meter can be used as either a
0-30V voltmeter or as a 0-500mA ammeter.
OUTPUT CONTROLS:
Coarse and fine voltage controls set desired
output voltage. Meter switch selects voltage or
current.
OUTPUT TERMINALS:
Three "five-way" output posts are provided on
the front panel All power supply output terminals
are isolated from the chassis and either the posi
tive or negative terminal may be connected to the
chassis through a separate ground terminal located
on the output terminal strip.
COOLING:
Convection cooling is employed. The supply
has no moving parts.
SIZE:
5i"/13,34cm W x 3i"/8,26cm H x 7"/l7„78cm D.
Using a Rack Mounting Kit, three units can be
mounted side by side in a standard 19" relay rack.
■WEIGHT:
5.25 lbs./2,38 kg. net, 71bs./3,17kg. shipping.
FINISH: DarkCray
POWER CORD:
A three-wire, five-foot power cord is provided
with each unit.
1-2

SECTION II
INSTALLATION
mnTTTTm
-
REAR
Figure 2-1. Outline Diagram
2-1 INITIAL INSPECTION
2-2 Before shipment, this instrument was inspec
ted and found to be free of mechanical and electri
cal defects. As soon as the instrument is unpacked,
inspect for any damage that may have occurred in
transit. Save all packing materials until the in
spection is completed. If damage is found, proceed
as described in the Claim for Damage in Shipment
section of the warranty page at the rear of this
manual.
2-3 MECHANICAL CHECK
2-4 This check should confirm that there are no
broken knobs or connectors, that the cabinet and
panel surfaces are free of dents and scratches,
and that the meter is not scratched or cracked.
2-5 ELECTRICAL CHECK
2-6 The instrument should be checked against its
electrical specifications. Section V includes an
"in-cabinet" performance check to verify proper in
strument operation.
2-7 INSTALLATION DATA
2-8 The instrument is shipped ready for bench
operation. It is necessary only to connect the in
strument to a source of power and it is ready for
operation.
2-9 LOCATION
2-10 This instrument is air cooled. Sufficient
space should be allotted so that a free flow of
cooling air can reach the rear of the instrument
when it is in operation. It should be used in an
area where the ambient temperature does not ex
ceed 550c.
2-11 OUTLINE DIAGRAM
2-12 Figure 2-1 illustrates the outline shape and
dimensions of Models 62I3A through 62I8A.
2-13 RACK MOUNTING
2-14 This instrument may be rack mounted sepa
rately or with a maximum of two other BENCH
Series supplies as shown in Figure 2-2. The
Figure 2-2. Rack Kit with Three BENCH Supplies
2-1

units are placed in the Rack Mounting Frame. The
Rack Mounting Frame is then fastened to the rack
frame.
2-15 INPUT POWER REQUIREMENTS
2-16 This power supply may be operated continu
ously from either a nominal 115 Volt or 230 Volt
50-400HZ power source. The unit as shipped from
the factory, is wired for 115 Volt operation. The
input power required when operated from a 115 Volt
power source at full load is:
Model Input Current
6213A and 6214A 0.29A
6215A and 6217A 0.25A
6216A and 6218A 0.25A
Input Power
28W
26W
26W
2-17 CONNECTIONS FOR 230 VOLT OPERATION
(Figure 2-3)
2-18 Normally, the two primary windings of the
input transformer are connected in parallel for op
eration from 115 Volt source. To convert the power
supply to operation from a 230 Volt source, the
power transformer windings are connected in series
as follows:
a. Unplug the line cord and remove the top
cover as described in Paragraph 5-3.
b. Remove the jumpers between taps 4-2 and
3-1. Solder a jumper between taps 3-2 on the input
power transformer Tl, see Figure 2-3.
c. Replace existing fuse with a 0.5 Ampere,
230 Volt fuse.
d. Replace existing line cord plug with a
standard 230 Volt plug.
2-19 POWER CABLE
2-20 To protect operating personnel, the National
Electrical Manufacturers Association (NEMA) recom
mends that the instrument panel and cabinet be
grounded. This instrument is equipped with a three
conductor power cable. The third conductor is the
ground conductor and when the cable is plugged
TRANSFORMER PRIMARY
CONNECTED FOR
115-VOLT OPERATION
TRANSFORMER PRIMARY
CONNECTED FOR
230-VOLT OPERATION
Figure 2-3. Input Power Transformer, Connections
into an appropriate receptacle, the instrument is
grounded. The offset pin on the power cable three-
prong connector is the ground connection.
2-21 To preserve the protection feature when oper
ating the instrument from a two-contact outlet, use
a three-prong to two-prong adapter and connect the
green lead on the adapter to ground.
2-22 REPACKAGING FOR SHIPMENT
2-23 To insure safe shipment of the instrument, it
is recommended that the package designed for the
instrument be used. The original packaging mate
rial is reusable. If it is not available, contact
your local Hewlett-Packard field otfice to obtain
the materials. This office will also furnish the ad
dress of the nearest service office to which the in
strument can be shipped. Be sure to attach a tag
to the instrument which specifies the owner, model
number, full serial number, and service required, or
a brief description of the trouble.
2-2

SECTION III
OPERATING INSTRUCTIONS
3-1 TURN-ON CHECKOUT PROCEDURE
3-5 CONSTANT VOLTAGE
3-2 The following checkout procedure describes
the use of the front panel controls and indicators
and ensures that the supply is operational;
a. Set AC toggle switch (1) upward to on
position; indicator (2) should light.
VOLTS
20 30 40
10 L L__/ 50
VOLTAGE
COARSE FINE
METER SELECTION
vOLTS^yjUgl^mA
+ GND
Figure 3-1. Front Panel Controls and Indicators
b. Set METER SELECTION switch (4) to
VOLTS position.
c. Turn COARSE (6) and FINE (5) VOLTAGE
controls fully ccw to ensure that output decreases
to OV, then turn the VOLTAGE controls fully cw to
ensure that output voltage increases to the maxi
mum rated output voltage.
d. Connect a milliammeter across the out
put of the supply (3) to check that the current
limit circuit within the supply is limiting the out
put current to:
Model Current Limit
6213A 1300 ±50mA
6215A 475 ±10mA
6217A 250 ±10mA
e. Remove milliammeter and connect load
to output terminals.
3-3 OPERATION
3-4 The power supply can be operated as a
single unit (normal operation), in parallel, or in
series. The output of the supply can be floated
up to 300 volts off ground.
3-6 To select a constant voltage output turn on
the supply and, with no load connected, adjust
the VOLTAGE controls for the desired output volt
age. To check the current limit, connect an ex
ternal ammeter across the output of the supply,
turn the VOLTAGE controls fully clockwise, and
observe the reading. The current limit is factory
adjusted in excess of the current rating of the
supply. If the existing current is not compatible
with the anticipated load requirements, the limit
can be changed as outlined in the following para
graphs.
3-7 CHANGING CURRENT LIMIT
3-8 The current limit can be varied by adjusting
resistor R50, located on the printed wiring board.
This adjustment procedure is described in Para
graph 5-63. The range of the current limit control
R50 is as follows:
Model Current Limit Range
6213A 800 - 1700mA
6215A 300 - 540mA
6217A 180 - 300mA
The current limit is normally adjusted to a
value far in excess of the current rating of the
supply to prevent the deterioration of line and
load regulation. Therefore, if for any reason the
current limit is adjusted so that the output current
is close to this value, the performance will not
meet the published specifications.
3-9 CONNECTING LOAD
3-10 Each load should be connected to the power
supply output terminals using separate pairs of
connecting wires. This will minimize mutual coup
ling effects between loads and will retain full ad
vantage of the low output impedance of the power
supply. Each pair of connecting wires should be
as short as possible and twisted or shielded to re
duce noise pickup. (If shield is used, connect
one end to power supply ground terminal and leave
the other end unconnected.)
3-11 If load considerations require that the output
power distribution terminals be remotely located
from the power supply, then the power supply out
put terminals should be connected to the remote
distribution terminals via a pair of twisted or
shielded wires and each load separately connected
3-1