Agilent Technologies E3620A Service manual

DUAL OUTPUT POWER SUPPLY
Agilent MODEL E3620A
OPERATING AND SERVICE MANUAL
FOR INSTRUMENTS WITH SERIAL NUMBERS
KR71804262 AND ABOVE
For instruments with Serial Numbers above
KR71804262, a change age may be included.
Manual Part No. E3620-90001
I
A ril 2000
Edition 6

1-2
SAFETY SUMMARY
The following general safety precautions must be observed during all phases of operation, service, and repair of this instrument.
Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design,
manufacture, and intended use of the instrument. Agilent Technologies assumes no liability for the customer's failure to comply
with these requirements.
BEFORE APPLYING POWER.
Verify that the product is set to match the available line volt-
age and that the correct fuse is installed.
GROUND THE INSTRUMENT.
This product is a Safety Class I instrument (provided ith a
protective earth terminal). To minimize shock hazard, the
instrument chassis and cabinet must be connected to an
electrical ground. The instrument must be connected to the
ac po er supply mains through a three-conductor po er
cable, ith the third ire firmly connected to an electrical
ground(safety ground) at the po er outlet. Any interruption of
the protective(grounding) conductor or disconnection of the
protective earth terminal ill cause a potential shock hazard
that could result in personal injury. If the instrument is to be
energized via an external autotransformer for voltage reduc-
tion, be certain that the autotransformer common terminal is
connected to the neutral(earthed pole) of the ac po er lines
(supply mains).
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do not operate the instrument in the presence of flammable
gases or fumes.
KEEP AWAY FROM LIVE CIRCUITS.
Operating personnel must not remove instrument covers.
Component replacement and internal adjustments must be
made by qualified service personnel. Do not replace compo-
nents ith po er cable connected. Under certain conditions,
dangerous voltages may exist even ith the po er cable
removed. To avoid injuries, al ays disconnect po er, dis-
charge circuits and remove external voltage sources before
touching components.
DO NOT SERVICE OR ADJUST ALONE.
Do not attempt internal service or adjustment unless another
person, capable of rendering first aid and resuscitation, is
present.
SAFETY SYMBOLS
Instruction manual symbol; the product
ill be marked ith this symbol hen it is
necessary for the user to refer to the
instruction manual.
Indicate earth(ground) terminal.
The WARNING sign denotes a hazard. It
calls attention to a procedure, practice,
or the like, hich, if not correctly per-
formed or adhered to, could result inper-
sonal injury. Do not proceed beyond a
WARNING sign until the indicated con-
ditions are fully understood and met.
The CAUTION sign denotes a hazard. It
calls attention to an operating procedure,
or the like, hich, if not correctly per-
formed or adhered to, could result in
damage to or destruction of part or all of
the product. Do not proceed beyond
CAUTION sign until the indicated condi-
tions are fully understood and met.
The NOTE sign denotes important infor-
mation. It calls attention to a procedure,
practice, condition or the like, hich is
essential to highlight.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because of the danger of introducing additional hazards, do
not install substitute parts or perform any unauthorized modi-
fication to the instrument. Return the instrument to a Agilent
Technologies Sales and Service Office for service and repair
to ensure that safety features are maintained.
Instruments that appear damaged or defective should be made inoperative and secured against unintended
operation until they can be repaired by qualified service personnel.
!
or
CAUTION
WARNING
NOTE

1-3
Table of Contents
SAFETY SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
SAFETY AND EMC REQUIREMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
INSTRUMENT AND MANUAL IDENTIFICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
ACCESSORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
ORDERING ADDITIONAL MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
LINE FUSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
INITIAL INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Mechanical Chec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Electrical Chec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
INSTALLATION DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Location and Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Outline Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Rac Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
INPUT POWER REQUIREMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Power Cable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
O ERATING INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Line Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Voltage and Current Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Voltage Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
TURN-ON CHECKOUT PROCEDURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Overload Protection Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Operation Beyond Rated Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Connecting Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Series Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Parallel Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
LOAD CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
PULSE LOADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
REVERSE CURRENT LOADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
OUTPUT CAPACITANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
REVERSE VOLTAGE PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

1-4
GENERAL INFORMATION
DESCRI TION
The Model E3620A Dual Output Po er Supply is a compact,
constant voltage/current limiting supply that delivers t o iso-
lated 0 to 25 V outputs rated at 1 A. It is an ideal po er supply
for design and breadboard ork here single or dual voltages
are required. Each output voltage is continuously variable
throughout its range and separate current limit circuits protect
each output against overload or short circuit damage.
Connections to the outputs are made to binding post type ter-
minals on the front panel. The outputs can be used individu-
ally or in combination to satisfy any number of output
demands. The positive or negative terminal of each output
can be grounded or each output can be left floating. A chassis
ground terminal is located on the front panel of the supply.
The front panel also contains a line s itch, output voltage
controls, an autoranging digital voltmeter and a single-range
digital ammeter, and t o meter select pushbutton s itches.
The meter pushbuttons select both voltage and current
monitoring for the output V1 and V2. The supply is furnished
ith a detachable, 3- ire grounding type line cord. The ac
line fuse is an extractor type fuseholder on the rear heat sink.
SAFETY CONSIDERATIONS
This product is a Safety Class I instrument, hich means that
it is provided ith a protective earth ground terminal. This ter-
minal must be connected to an ac source that has a 3- ire
ground receptacle. Revie the instrument rear panel and this
manual for safety markings and instructions before operating
the instrument. Refer to the Safety Summary page at the
beginning of this manual for a summary of general safety
information. Specific safety information is located at the
appropriate places in this manual.
SAFETY AND EMC REQUIREMENTS
This po er supply is designed to comply ith the follo ing
safety and EMC(Electromagnetic Compatibility) require-
ments:
nIEC 1010-1(1990)/EN 61010 (1993): Safety Require-
ments for Electrical Equipment for Measurement, Control,
and Laboratory Use
nCSA C22.2 No.231: Safety Requirements for Electrical
and Electronic Measuring and Test Equipment
nUL 1244: Electrical and Electronic Measuring and Testing
Equipment
nEMC Directive 89/336/EEC: Council Directive entitled
Approximation of the La s of the Member States relating
to Electromagnetic Compatibility
n EN 55011(1991) Group 1, Class B/CISPR 11 (1990):
Limits and Methods of Radio Interference Characteristics
of Industrial, Scientific, and Medical(ISM) Radio-
Frequency Equipment
nEN 50082-1(1992) /
IEC 801-2(1991): Electrostatic Discharge Requirements
IEC 801-3(1984): Radiated Electromagnetic Field
Requirements
IEC 801-4(1988): Electrical Fast Transient/Burst
Requirements
INSTRUMENT AND MANUAL IDENTIFICATION
A serial number identifies your po er supply. The serial num-
ber encodes the country of manufacture, the eek of the lat-
est significant design change, and a unique sequential
number. The letter "KR" designates Korea as the country of
manufacture, the first one digit indicates the year (4=1994,
5=1995, and so forth), and the second t o digits indicate the
eek. The remaining digits of the serial number are a unique,
five-digit number assigned sequentially.
If the serial number on your supply does not agree ith those
on the title page of the manual, a yello Change Sheet is
supplied ith the manual to explain the difference bet een
your instrument and the instrument described by this manual.
The Change Sheet may also contain information for correct-
ing errors in the manual.
O TIONS
Options 0E3 and 0E9 determine hich line voltage is
selected at the factory. The standard unit is configured for 115
Vac ± 10%, 47-63 Hz input.
Option No. D scription
0E3: 230 Vac ± 10%, 47-63 Hz Input
0E9: 100 Vac ± 10%, 47-63 Hz Input
ACCESSORY
The accessory listed belo may be ordered from your local
Agilent Technologies Sales Office either ith the po er sup-
ply or separately. (Refer to the list at the rear of the manual for
address.)
Agil nt Part No. D scription
5063-9240 Rack Kit for mounting one or t o 3 1/2" high
supplies in a standard 19" rack
The rack mount kit is needed for rack mounting of the
E3620A po er supply.
ORDERING ADDITIONAL MANUALS
One manual is shipped ith each po er supply. (Option 910
is ordered for each extra manual.) Additional manuals may
also be purchased separately for your local Agilent Technolo-
gies sales office (see the list at the rear of this manual for
addresses). Specify the model number, serial prefix, and the
Agilent Part Number provided on the title page.
S ECIFICATIONS
Instrument specifications are listed in Table 1. These specifi-
cations are performance standards or limits against hich the
instrument is tested.

1-5
LINE FUSE
The line fuse is located by the ac line receptacle. Check the
rating of the line fuse and replace it ith the correct fuse if
necessary as indicated belo . These are slo -blo fuses.
Lin Voltag Fus Agil nt Part No.
100/115 Vac 2 A 2110-0702
230 Vac 1 A 2110-0457
Table 1. Specifications
AC INPUT
Standard: 115 Vac ± 10%, 47-63 Hz, 200 VA, 130 W
0E9: 100 Vac ± 10%, 47-63 Hz, 200 VA, 130 W
0E3: 230 Vac ± 10%, 47-63 Hz, 200 VA, 130 W
DC OUTPUT
Voltage span over hich output may be varied using front
panel controls.
Output V1: 0 to 25 V at 1 A
Output V2: 0 to 25 V at 1 A
LOAD REGULATION
Less than 0.01% plus 2 mV for a full load to no load change in
output current.
LINE REGULATION
Less than 0.01% plus 2 mV for any line voltage change ithin
rating.
RIPPLE AND NOISE
Normal Mode Voltage: Less than 0.35 mV rms/1.5 mV p-p
(20 Hz-20 MHz).
Common Mode Current (CMI): Less than 1 mA rms for all
outputs (20 Hz-20 kHz).
OPERATING TEMPERATURE RANGE
0 to 40 oC for full rated output. At higher temperatures,
output current is derated linearly to 50% at 55 oC maximum
temperature.
TEMPERATURE COEFFICIENT
Less than 0.02% plus 1 mV voltage change per oC over the
operating range from 0 to 40 oC after 30 minutes arm-up.
STABILITY (OUTPUT DRIFT)
Less than 0.1% plus 5 mV (dc to 20 Hz) during 8 hours at
constant line, load and ambient after an initial arm-up time
of 30 minutes.
LOAD TRANSIENT RESPONSE TIME
Less than 50 msec for output recovery to ithin 15 mV of
nominal output voltage follo ing a load change from full
load to half load, or vice versa.
OUTPUT VOLTAGE OVERSHOOT
During turn-on or turn-off of ac po er, output plus overshoot
ill not exceed 1 V if the output control is set for less than 1 V.
If the control is set for 1 V or higher, there is no overshoot.
METER ACCURACY: ±(0.5% of output + 2 counts)
at 25oC±5oC
METER RESOLUTION
Voltage: 10 mV (0 to 20 V),100 mV (above 20 V)
Current: 1 mA
DIMENSIONS
212.3 mmW x 88.1 mmH x 345.4 mmD
(8.4 inW x 3.5 inH x 13.6 inD)
WEIGHT
5.0 kg(11.0 lbs) net, 6.25 kg(13.8 lbs) shipping
INSTALLATION
INITIAL INS ECTION
Before shipment, this instrument as inspected and found to
be free of mechanical and electrical defects. As soon as the
instrument is unpacked, inspect for any damage that may
have occurred in transit. Save all packing materials until the
inspection is completed. If damage is found, a claim should
be filed ith the carrier. The Agilent Technologies Sales and
Service office should be notified as soon as possible.
Mechanical Check
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.
Electrical Check
This instrument should be checked against electrical specifi-
cations. Perform the TURN-ON CHECKOUT PROCEDURE
in the follo ing paragraph to confirm that the supply is
operational. Alternately, check the supply more fully using the
PERFORMANCE TEST in the service information section.
INSTALLATION DATA
The instrument is shipped ready for bench operation. Before
applying po er to the supply, please read the INPUT
POWER REQUIREMENTS paragraph.
Location and Cooling
This instrument is air cooled. Sufficient space should be allo ed
so that a free flo of cooling air can reach the sides and rear of
the instrument hen it is in operation. It should be used in an
area here the ambient temperature does not exceed 40oC.

1-6
Outline Diagram
Figure 1 illustrates the outline shape and dimensions of the
supply.
Rack Mounting
This supplymaybe rack mounted in a standard 19-inch rack
panel either byitself or alongside a similar unit. Please see
the ACCESSORY, page 1-4, for available rack mounting
accessory. The rack-mountingkit includes complete installa-
tion instructions.
INPUT POWER REQUIREMENTS
Dependingon the line voltage option ordered, the supplyis
readyto be operated from one of the power sources listed in
Table 1. A label on the rear heat sink shows the nominal input
voltage set for the supplyat the factory.
Power Cable
To protect operatingpersonnel, the supplyshould be
grounded. This supplyis equipped with a three conductor
power cable. The third conductor is the ground conductor and
when the cable is plugged into an appropriate receptacle, the
supplyis grounded. The power supplyis equipped at the fac-
torywith a power cord plugappropriate for the user's location.
Notifythe nearest Agilent Sales and Service Office if the
appropriate power cord is not included with the supply.
Figure 1. Outline Diagram
OPERATING INSTRUCTIONS
INTRODUCTION
This section describes the operatingcontrols and indicators,
turn-on checkout procedures, and other operatingconsider-
ations for the Model E3620A Dual Output Power Supply.
Before applyingpower to the supply, check the label on the
heat sink to make certain that the supply's line voltage option
agrees with the line voltage to be used. If the option does not
correspond to your line voltage, refer to paragraph "LINE
VOLTAGE OPTION CONVERSION" in the service section
before applyingpower.
Figure 2. Front-Panel Controls and Indicators
CONTROLS
Line Switch
The LINE pushbutton switch ( , Figure 2) is pushed-in to
turn the supplyON and released (out position) to turn the
supplyOFF.
Voltage and Current Metering
Two meter select pushbutton switches ( and ) permit the
output voltage and current of either output (V1 or V2) to be
monitored on the VOLTS/AMPS meter. The V1 and V2 output
select pushbuttons connect the desired output to the meter-
ingcircuit when the applicable button is pushed in.
Be careful that both METER pushbuttons are not released
(out-position) or pushed in simultaneously.
Voltage Controls
The V1 and V2 voltage controls ( and ) set the voltage
level of the correspondingoutput. The voltage controls are 10
turn potentiometers.

1-7
TURN-ON CHECKOUT PROCEDURE
The followin
g
steps describe the use of the Model E3620A
front panel controls illustrated in Fi
g
ure 2 and serve as a brief
check that the suppl
y
is operational. Follow this checkout pro-
cedure or the more detailed performance test of service infor-
mation section when the instrument is received and before it
is connected to an
y
load equipment. Proceed to the more
detailed performance test be
g
innin
g
in service information
section if an
y
difficulties are encountered.
a. Connect line cord to power source and push LINE
switch ( ) in.
b. Push the V1 meter select pushbutton switch ( ) to in-
position to monitor suppl
y
's V1 output volta
g
e. With no
load connected, var
y
the V1 volta
g
e control ( ) over its
ran
g
e and check that the voltmeter responds to the con
trol settin
g
and the ammeter indicates zero.
c. Turn the V1 volta
g
e control ( ) full
y
clockwise and
short the +V1 output terminal ( ) to -V1 terminal ( )
with an insulated test lead. The ammeter should indi-
cate a short-circuit output current of minimum 1.0 A +
5% at 25 oC. Remove the short from the output termi-
nals.
d. Push the V2 meter select pushbutton switch to in-
position and repeat steps (b) and (c) for V2 output.
If this brief checkout procedure or later use of the suppl
y
reveals a possible malfunction, see the service information
section for detailed test, troubleshootin
g
, and adjustment pro-
cedures.
OPERATION
The dual outputs of the E3620A can be used individuall
y
, in
series, or in parallel. Each output can be floated (up to 240
volts off
g
round) or, the + or - terminal of either output can be
g
rounded to the chassis
g
round terminal which is located on
the suppl
y
's front panel.
Overload Protection Circuits
The outputs are individuall
y
protected a
g
ainst overload or
short circuit dama
g
e b
y
separate current limitin
g
circuits. The
circuits are factor
y
adjusted to limit the output current to mini-
mum 1 A + 5%. The current limits are set b
y
adjustin
g
R63 in
the V1 suppl
y
and R34 in the V2 suppl
y
(see the schematic
dia
g
ram). No deterioration of suppl
y
performance occurs if
the output current remains below the current limit settin
g
.
Durin
g
the actual operation of the V1 and V2 outputs, if a load
chan
g
e causes the current limit to be exceeded, the OVER-
LOAD LED is li
g
hted. If overload conditions occur, the V1 and
V2 supplies will protect the load b
y
limitin
g
the current to min-
imum 1 A + 5%. The V1 and V2 supplies are self restorin
g
;
that is, when the overload is removed or corrected, the output
volta
g
e is automaticall
y
restored to the previousl
y
set value.
Operation Beyond Rated Output
The suppl
y
ma
y
be able to provide volta
g
es and currents
g
reater than its rated maximum outputs if the line volta
g
e is at
or above its nominal value. Operation can be extended up to
5% over the rated output without dama
g
e to the suppl
y
, but
performance can not be
g
uaranteed to meet specifications
above the rated output of 0 to 25 V at 1 A.
Connecting Load
Connect each load to the power suppl
y
output terminals usin
g
separate pairs of connectin
g
wires. This will minimize mutual
couplin
g
effects between loads and takes full advanta
g
e of
the low output impedance of the suppl
y
. Load wires must be
of adequatel
y
heav
y
g
au
g
e to maintain satisfactor
y
re
g
ulation
at the load.
Make each pair of connectin
g
wires as short as possible and
twist or shield them to reduce noise pick-up. If a shield is
used, connect one end of the shield to the power suppl
y
g
round terminal and leave the other end unconnected.
If load considerations require locatin
g
output power distribution
terminals at a distance from the power suppl
y
, then the power
suppl
y
output terminals should be connected to the remote dis-
tribution terminals b
y
a pair of twisted or shielded wires and each
load should be connected to the remote distribution terminals
separatel
y
.
Series Operation
The two outputs (V1 and V2) can be connected in series to
obtain a volta
g
e (up to 50 V) hi
g
her than that available from a
sin
g
le output. Each output control (V1 and V2) must be adjusted
in order to obtain the total output volta
g
e. Diodes connected
internall
y
across each output protect the suppl
y
's output filter
capacitors a
g
ainst reverse volta
g
es. This could occur if the sup-
plies are connected in series and the output is shorted.
Parallel Operation
The V1 and V2 supplies can be connected in parallel to obtain a
total output current
g
reater than that available from one suppl
y
.
The total output current is the sum of the output currents of the
individual supplies. The output volta
g
e controls of one power
suppl
y
should be set to the desired output volta
g
e, and the other
suppl
y
set for a sli
g
htl
y
lar
g
er output volta
g
e. The suppl
y
set to
the lower output volta
g
e will act as a constant volta
g
e source,
while the suppl
y
set to the hi
g
her output will act as a current-lim-
ited source, droppin
g
its output volta
g
e until it equals that of the
other suppl
y
. The constant volta
g
e source will deliver onl
y
that
fraction of its rated output current necessar
y
to fulfill the total cur-
rent demand.
LOAD CONSIDERATIONS
This section provides information on operatin
g
y
our suppl
y
with various t
y
pes of loads connected to its output.
PULSE LOADING
The power suppl
y
will automaticall
y
cross over from constant-
volta
g
e to current-limit operation in response to an increase in
the output current over the preset limit. Althou
g
h the preset
limit ma
y
be set hi
g
her than the avera
g
e output current, hi
g
h

1-8
peak currents (as occur in pulse loadin
g
) ma
y
exceed the
preset current limit and cause crossover to occur and
de
g
rade performance.
REVERSE CURRENT LOADING
An active load connected to the suppl
y
ma
y
actuall
y
deliver a
reverse current to the suppl
y
durin
g
a portion of its operatin
g
c
y
cle. An external source can not be allowed to pump current
into the suppl
y
without riskin
g
loss of re
g
ulation and possible
dama
g
e to the output capacitor of the suppl
y
. To avoid these
effects, it is necessar
y
to preload the suppl
y
with a dumm
y
load resistor so that the suppl
y
delivers current throu
g
h the
entire operatin
g
c
y
cle of the load devices.
Fi
g
ure 3. Reverse Current Loadin
g
Solution
OUTPUT CAPACITANCE
An internal capacitor across the output terminals of the suppl
y
helps to suppl
y
hi
g
h-current pulses of short duration durin
g
constant-volta
g
e operation. An
y
capacitance added exter-
nall
y
will improve the pulse current capabilit
y
, but will
decrease the load protection provided b
y
the current limitin
g
circuit. A hi
g
h-current pulse ma
y
dama
g
e load components
before the avera
g
e output current is lar
g
e enou
g
h to cause
the current limitin
g
circuit to operate.
REVERSE VOLTAGE PROTECTION
A diode is connected across the output terminals with reverse
polarit
y
. This diode protects the output electrol
y
tic capacitors
and the series re
g
ulator transistors from the effects of a
reverse volta
g
e applied across the output terminals. Since
series re
g
ulator transistors can not withstand reverse volta
g
e
either, diodes are also connected across them. When operat-
in
g
supplies in parallel, these diodes protect an unener
g
ized
suppl
y
that is in parallel with an ener
g
ized suppl
y
.

A-1
SERVICE INFORMATION
Figure A-1. Block Diagram
PRINCIPLES OF OPERATION
(Block Diagram Overview)
This section presents the principles of operation for the
E3620A Dual Output Power Supply. Throu hout this discus-
sion, refer to both the block dia ram of Fi ure A-1 and the
schematic of Fi ure A-10 and Fi ure A-11.
The E3620A contains two independent power supplies (des-
i nated V1 and V2), a common input power circuit, and a
meter circuit that can monitor the output volta e and current
of either supply.
The two primary windin s of the power transformer are con-
nected in one of three different ways by settin the two slide
switches mounted on the circuit board. These switches select
one of the nominal ac input volta es for which the supply is
desi ned: 100 V, 115 V, or 230 V. The transformer secondar-
ies, to ether with rectifiers and capacitor filters, provide raw
dc for two output re ulator circuits, for two reference and bias
supplies and for a display power supply.
By comparin its output to a hi h-stability reference, the V1
supply's 0 to 25 V re ulator holds its output volta e at the
value determined by the V1 VOLTAGE control of the front
panel. Any error in the actual output as compared to the
desired output is amplified by an operational amplifier and
applied as feedback to control the conduction of a series re -
ulator transistor. As a result, the volta e across the series
transistor varies so as to hold the output volta e constant at
the desired level. The hi h ain of the volta e comparison
amplifier and the stability of the reference volta e ensure that
input volta e or load current variations have little effect on the
output volta e. The V1 output is protected by a fixed current
limit at minimum 105% of its 1 amp maximum rated output.

A-2
The input ac line volta
g
e is first applied to the prere
g
ulator
which operates in conjunction with the prere
g
ulator control
circuit to rectif
y
the tap switched AC volta
g
e. This prere
g
u-
lator minimizes the power dissipated in the series re
g
ulatin
g
elements b
y
controllin
g
the dc level across the input filter
capacitors dependin
g
on the output volta
g
e.
To achieve this, tap switchin
g
of the V1 output is accom-
plished b
y
a TRIAC(Q5), a brid
g
e diode (CR4), two
diodes(CR5 and CR6) and the prere
g
ulator control circuit.
This circuit allows the input capacitors to char
g
e to one of two
discrete volta
g
e levels dependin
g
on the output required.
When the output volta
g
e exceeds the reference level, the pre-
re
g
ulator control circuit fires the TRIAC Q5 that causes the
input capacitors to be char
g
ed to the volta
g
e which is neces-
sar
y
for full output of the suppl
y
. When the TRIAC is not fired,
the brid
g
e diode CR4 conducts and half the volta
g
e is applied
to series pass transistor Q2.
The re
g
ulator of the V2 output is, in turn, similar to that of the
V1 output re
g
ulator except that it has two TRIACs(Q3 and
Q4) and two brid
g
e diodes(CR2 and CR3) to allow the input
capacitors to be char
g
ed to one of four discrete volta
g
e levels
dependin
g
on the output required in order to minimize power
dissipation in the series re
g
ulator transistor Q1.
The main secondar
y
windin
g
of the power transformer has
three sections (N1, N2, and N3), each of which has a different
turns ratio with respect to the primar
y
windin
g
. At the be
g
in-
nin
g
of each half-c
y
cle of the input ac, the control circuit
determines whether one, both or none of the TRIAC will be
fired. If neither TRIAC is fired, the brid
g
e diodes (CR2 and
CR3) receive an ac input volta
g
e that is determined b
y
N1
turns (tap 18 and 19 of the power transformer) and the input
capacitors char
g
e to a correspondin
g
level. If TRIAC Q3 is
fired, input capacitors char
g
e to the volta
g
e determined b
y
N1+N2 turns. Similarl
y
, if TRIAC Q4 is fired the capacitors are
char
g
ed b
y
N1 + N3. Finall
y
, if all TRIACs are fired simulta-
neousl
y
, input capacitors char
g
e to its hi
g
hest volta
g
e level
determined b
y
N1 + N2 + N3 turns (tap 17 and 20 of the
power transformer).
The TRIAC control circuit determines which TRIACs are to be
fired b
y
monitorin
g
the output volta
g
e and comparin
g
these
values a
g
ainst a set of three internall
y
derived reference lev-
els. These three reference levels are translated into boundar
y
lines to allow the output characteristic to be mapped into four
operatin
g
re
g
ions (Fi
g
ure A-2). The boundar
y
lines, which are
invisible to the user, are divided into four operatin
g
re
g
ions
(V1, V2, V3, and V4) to minimize the power dissipation in the
series pass transistors. Whenever the output volta
g
e is below
the slopin
g
V1 line, the control circuit inhibits two TRIACs and
the input capacitors char
g
e to a volta
g
e determined b
y
N1.
Fi
g
ure A-2 indicates the windin
g
s that are connected as a
result of the other volta
g
e decisions.
The reference and bias supplies of each suppl
y
power the
operational amplifiers and provide reference and bias volt-
a
g
es for the output re
g
ulators. The displa
y
power circuit pro-
vides volta
g
e which is used b
y
the A/D converter and displa
y
.
Fi
g
ure A-2. Output Power Plot
Diode CR13 and CR19 are connected across the output
terminals in reverse polarit
y
. The
y
protect the output
electrol
y
tic capacitor and the series re
g
ulator transistors from
a reverse volta
g
e applied across the output terminals.
Two meter pushbutton switches select which suppl
y
(V1 or
V2) has its output volta
g
e and current indicated on the front
panel meters.
MAINTENANCE
INTRODUCTION
This section provides performance test, troubleshootin
g
infor-
mation, and adjustment and calibration procedures. The fol-
lowin
g
operation verification tests comprise a short procedure
to verif
y
that the power suppl
y
is performin
g
properl
y
, without
testin
g
all specified parameters.
If a fault is detected in the power suppl
y
while makin
g
the
performance check or durin
g
normal operation, proceed to
the troubleshootin
g
procedures. After troubleshootin
g
, per-
form an
y
necessar
y
adjustments and calibrations. Before
returnin
g
the power suppl
y
to normal operation, repeat the
performance check to ensure that the fault has been properl
y
corrected and that no other faults exist.
Test Equipment Required
Table A-1 lists the equipment required to perform the various
procedures described in this section.
Operation Verification Tests
The followin
g
tests assure that the power suppl
y
is per-
formin
g
properl
y
. The
y
do not, however, check all the speci-
fied parameters tested in the complete performance test
described below. Proceed as follows:
a. Perform turn-on checkout procedure
g
iven in pa
g
e 1-7.
b. Perform the load re
g
ulation performance tests
g
iven in
the followin
g
para
g
raphs.

A-3
Line Voltage Option Conversion
To convert the supplyfrom one line voltage option to another,
the followingthree steps are necessary:
a.After makingcertain that the line cord is disconnected
from a source of power, remove the top cover from the
supplyand set the two sections of the line voltage selec-
tor switch for the desired line voltage (see Figure A-3).
b.Check the ratingof the installed fuse and replace it with
the correct value, if necessary. For Option OE3, use a
slow-blow 1 amp fuse. For standard and Option OE9, use
a slow-blow 2 amp fuse.
c.Mark the instrument clearly with a tag or label indicating
the correct line voltage to be used.
Figure A-3. Line Voltage Selector (set for 115 Vac)
PERFORMANCE TESTS
The followingparagraphs provide test procedures for verify-
ing the power supply's compliance with the specifications of
Table 1. Proceed to the troubleshootingprocedures if you
observe anyout of specification performance.
Before applyingpower to the supply, make certain
that its line voltage selector switch (S1) is set for the
line voltage to be used. (See CAUTION notice in
operatingsection for additional information on S1.)
General Measurement Techniques
ConnectingMeasuringDevices. To achieve valid results
when measuringload regulation, ripple and noise, and transient
response time of the supply, measuringdevices must be con-
nected as close to the output terminals as possible. A measure-
ment made across the load includes the impedance of the leads
to the load. The impedance of the load leads can easilybe sev-
eral orders of magnitude greater than the supplyimpedance and
thus invalidate the measurement. To avoid mutual coupling
effects, each measuringdevice must be connected directlyto
the output terminals byseparate pairs of leads.
When performance measurements are made at the front ter-
minals (Figure A-4) the load should be plugged into the front
of the terminals at (B) while the monitoringdevice is con-
nected to a small lead or bus wire inserted through the hole in
the neck of the bindingpost at (A). Connectingthe measuring
device at (B) would result in a measurement that includes the
resistance of the leads between the output terminals and the
point of connection.
SelectingLoad Resistors. Power supplyspecifications are
checked with a full load resistance connected across the sup-
plyoutput. The resistance and wattage of the load resis-
tor,therefore, must permit operation of the supplyat its rated
output voltage and current. For example, a supplyrated at 25
Table A-1. Test Equipment Required
TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED
MODEL
Oscilloscope Sensitivity: 100BµV
Bandwidth : 20 MHz/100 MHz Displaytransient response and ripple
and noise waveforms. Agilent 54503A
RMS Voltmeter True rms, 20 MHz bandwidth
Sensitivity: 1 mV
Accuracy: 5%
Measure rms ripple and noise
voltage.
Multimeter Resolution : 100 nV
Accuracy: 0.0035% Measure dc voltages. Agilent 34401A
Electronic Load Voltage Range : 240 Vdc
Current Range : 10 Adc
Open and short switches
Transient on/off
Measure load and line regulation. Agilent 6063A
Resistive Loads (RL)25BΩB5% 100 W Measure ripple and noise.
Current Sampling
Resistor (Shunt) 0.1BΩ0.1% 3 W Measure output current.
Variable Voltage
Auto Transformer Range : 85-130 and 200-260 Volts Vary ac input.

A-4
Fi
g
ure A-4. Front Panel Terminal Connections
volts and 1 amp would require a load resistance of 25 Ωat
the rated output volta
g
e. The watta
g
e ratin
g
of this resistor
would have to be at least 25 watts.
Electronic Load. Some of the performance test procedures
require to use an electronic load to test the suppl
y
quickl
y
and
accuratel
y
. An electronic load is considerabl
y
easier to use
than a load resistor. It eliminates the need for connectin
g
resistors or rheostats in parallel to handle the power, and it is
much more stable than a carbon-pile load. It is easier to
switch between load conditions as required for the load re
g
u-
lation and load transient response tests.
Output Current Measurement. For accurate output current
measurements, a current samplin
g
resistor should be
inserted between the load and the output of the suppl
y
. To
simplif
y
g
roundin
g
problems, one end of this samplin
g
resis-
tor should be connected to the same output terminal of the
suppl
y
which will be shorted to
g
round. An accurate voltmeter
is then placed across the samplin
g
resistor and the output
current is calculated b
y
dividin
g
the volta
g
e across the sam-
plin
g
resistor b
y
its ohmic value. The total resistance of the
series combination should be equal to the full load resistance
as determined in the precedin
g
para
g
raphs. Of course, if the
value of the samplin
g
resistor is ver
y
low when compared to
the full load resistance, the value of the samplin
g
resistor ma
y
be i
g
nored. The meter shunt recommended in Table A-1, for
example, has a resistance of onl
y
100 mΩand can be
ne
g
lected when calculatin
g
the load resistance of the suppl
y
.
Fi
g
ure A-5 shows a four terminal meter shunt. The load cur-
rent throu
g
h a shunt must be fed from the extremes of the
wire leadin
g
to the resistor while the samplin
g
connections
are made as close as possible to the resistance portion itself.
Fi
g
ure A-5. Current Samplin
g
Resistor Connections
Rated Output, Meter Accuracy, and Current Limit
To check that all supplies will furnish their maximum rated output
volta
g
e and current, that the front panel meters are accurate,
and that the current limit circuits function, proceed as follows:
Rated Output Volta
g
e and Voltmeter Accurac
y
a. With no loads connected: turn on the suppl
y
and push the
V1 METER switch in. Connect a DVM between the V1 +
and - terminals and set V1 VOLTAGE control until front
panel voltmeter indicates 17.00 volts.
b. Check the DVM indication. It should be within ±(0.5% + 2
counts) of the front panel voltmeter indication (16.90 to
17.10 V).
c. Set V1 VOLTAGE control clockwise until front panel volt-
meter indicates 25.0 volts.
d. DVM should indicate 25 volts ±(0.5% + 2 counts) (24.675
V to 25.325 V).
e. Repeat steps (a) throu
g
h (d) for the V2 suppl
y
.
Rated Output Current and Ammeter Accurac
y
f. Connect the test setup shown Fi
g
ure A-6 to the V1 sup-
pl
y
's + and - output terminals.
g
. Push the V1 METER switch in to monitor the V1 suppl
y
's
output current.
h. Close the load switch and adjust V1 VOLTAGE control
until front panel ammeter indicates 1.000 A.
i. Check that DVM indicates a volta
g
e drop across the cur-
rent samplin
g
resistor that corresponds to a current of 1
amp ±(0.5% + 2 counts) (0.993 A to 1.007 A).
j. Open the load switch and repeat steps (f) throu
g
h (i) for
the V2 suppl
y
.
Fi
g
ure A-6. Output Current, Test Set Up
Current Limit
k. Disconnect all loads from the suppl
y
.
l. Connect the test setup shown in Fi
g
ure A-6 to the V1
suppl
y
's + and - output terminals. Substitute a short for RL
and leave the load switch open.
m. Push the V1 METER switch in and adjust the V1 VOLT-
AGE control full
y
clockwise.
n. Close the load switch and determine the current flow
throu
g
h the current samplin
g
resistor RSb
y
measurin
g
its
volta
g
e drop with the DVM. The current should be mini-
mum 1 A + 5%.
o. Open the load switch and repeat steps (k) throu
g
h (n) for
the V2 suppl
y
.

A-5
Load Re
g
ulation (Load Effect)
Definition: The chan
g
e, EOUT, in the static value of dc out-
put volta
g
e resultin
g
from a chan
g
e in load resistance from
open circuit to the value that
y
ields maximum rated output
current (or vice versa).
To check the load re
g
ulation:
a. Connect the test equipment across the output of the V1 sup-
pl
y
as shown in Fi
g
ure A-7. Operate the electronic load in
constant current mode and set its current to 1.000 A.
b. Turn on the suppl
y
. Push the V1 METER switch in and
adjust its volta
g
e to 25.0 volts.
c. Record the volta
g
e indicated on the DVM.
d. Operate the electronic load in open (input off) mode and
recheck the DVM indication after readin
g
settles. It should
be within 0.01% plus 2 mV of the readin
g
in step (c).
e. Repeat steps (a) throu
g
h (d) for the V2 suppl
y
.
Fi
g
ure A-7. Basic Test Setup
Line Re
g
ulation (Source Effect)
Definition: The chan
g
e, EOUT, in the static value of dc out-
put volta
g
e resultin
g
from a chan
g
e in ac input volta
g
e from a
minimum to a maximum value (±10% of nominal volta
g
e).
To check the line re
g
ulation:
a. Connect a variable autotransformer between the input
power source and the power suppl
y
line plu
g
.
b. Connect the test equipment across the output of the V1 sup-
pl
y
as shown in Fi
g
ure A-7. Operate the electronic load in
constant current mode and set its current to 1.000 A.
c. Adjust the autotransformer for a low line input (-10% of
nominal volta
g
e).
d. Turn on the power. Push the V1 METER switch in and
adjust the output of the suppl
y
to 25.0 volts, and record
the DVM indication.
e. Adjust the autotransformer for hi
g
h line volta
g
e input (+10%
of nominal volta
g
e) and recheck the DVM indication. It
should be within 0.01% plus 2 mV of the readin
g
in step (d).
f. Repeat steps (b) throu
g
h (e) for the V2 suppl
y
.
Ripple and Noise(Normal Mode Volta
g
e)
Definition: Ripple and noise are measured in the rms or peak-
to-peak value over a 20 Hz to 20 MHz bandwidth. Fluctuations
below the lower frequenc
y
limit are treated as drift.
RMS Measurement
The rms measurement is not an ideal representation of the
noise, since fairl
y
hi
g
h output noise spikes of short duration
could be present in the ripple and not appreciabl
y
increase
the rms value.
To measure the ripple and noise of the rms value on each
output suppl
y
output:
a. Connect the test equipment across the output of the V1
suppl
y
as shown in Fi
g
ure A-8.
b. Turn on the suppl
y
and push the V1 METER switch in.
c. Adjust the output of the V1 suppl
y
to 25.0 volts.
d. Check that the rms noise volta
g
e at the true rms voltme-
ter is less than 0.35 mV.
e. Repeat steps (a) throu
g
h (d) for the V2 suppl
y
.
Fi
g
ure A-8. Ripple and Noise rms Measurement Test
Setup
Peak-to-Peak Measurement
The peak-to-peak measurement is particularl
y
important for
applications where noise spikes could be detrimental to a
sensitive load, such as lo
g
ic circuitr
y
.
To measure the ripple and noise of the peak-to-peak value on
each output suppl
y
output:
a. Connect the test equipment across the output of the V1
suppl
y
as shown in Fi
g
ure A-8, but replace the true rms
voltmeter with the oscilloscope.
b. Turn on the suppl
y
and push the V1 METER switch in.
c. Adjust the output of the V1 suppl
y
to 25.0 volts.
d. Set the oscilloscope to AC mode and bandwidth to 20 MHz.
e. Check that the peak-to-peak noise is less than 1.5 mV.
f. Repeat steps (a) throu
g
h (e) for the V2 suppl
y
.
Common Mode Current (CMI)
Definition : Common mode current is that ac current compo-
nent which exists between an
y
or all suppl
y
or output lines
and chassis
g
round.
To measure the common mode current:
a. Connect the full load for the V1 output terminal.
b. Connect a 100 kΩresistor(RS) and a 2200 pF capacitor
in parallel between V1 - terminal and chassis
g
round.



A-6
c. Connect the DVM across RS. Operate the DVM in ac volt-
age mode.
d. Turn on the supply.
e. Record the voltage across RSand convert it to current by
dividing this voltage by RS.
f. Check that the current is less than 1 µA.
g. Repeat steps (a) through (f) for the V2 supply.
Load Transient Response Time
Definition : This is the time for the output voltage to return to
within a specified band around its voltage following a change
from full load to half load or half load to full load.
To measure the load transient response time:
a. Connect the test equipment across the output of the V1
supply as shown in Figure A-7, but replace the DVM with
the oscilloscope. Operate the electronic load in constant
current mode.
b. Turn on the supply and push the V1 METER switch in.
c. Turn up V1 output voltage to 25.0 volts.
d. Set the electronic load to transient operation mode
between one half of supply's full rated value and supply's
full rated value at a 1 kHz rate with 50% duty cycle.
e. Set the oscilloscope for ac coupling, internal sync and
lock on either the positive or negative load transient.
f. Adjust the oscilloscope to display transients as shown in
Figure A-9.
g. Check that the pulse width (t2-t1) of the transients at 15
mV from the base line is no more than 50 µsec as shown.
h. Repeat steps (a) through (g) for the V2 supply.
Stability (Drift)
Definition: The change in output voltage (dc to 20 Hz) for the
first 8 hours following a 30-minute warm-up period with con-
stant input line voltage, constant load resistance and constant
ambient temperature.
To measure the stability:
a. Connect the test equipment across the output of the V1
supply as shown in Figure A-7.
b. Operate the electronic load in constant current mode and
set its current to 1.000 A.
c. Turn on the supply and push the V1 METER switch in.
d. Turn up V1 output voltage to 25.0 volts as read on the
digital voltmeter.
e. After a 30-minute warm-up, note the voltage on DVM.
f. The output voltage reading should deviate less than 0.1%
plus 5 mV from the reading obtained in step (e) over a
period of 8 hours.
g. Repeat steps (a) through (f) for the V2 supply.
Figure A-9. Load Transient Response Time Waveform

A-7
TROUBLESHOOTING
Before attemptin
g
to troubleshoot the power suppl
y
, ensure
that the fault is with the suppl
y
and not with an associated
piece of equipment. You can determine this without removin
g
the covers from the power suppl
y
b
y
usin
g
the appropriate
portions of the "Performance Tests" para
g
raph.
Before appl
y
in
g
power to the suppl
y
, make certain
that its line volta
g
e selector switch (S1) is set for the
line volta
g
e to be used.
Initial Troubleshooting Procedure
If a malfunction is found, follow the steps below:
a. Disconnect input power from the suppl
y
and remove all
loads from the output.
b. Table A-2 lists the s
y
mptoms and probable causes of
several possible troubles. If the s
y
mptoms is one of those
listed, make the recommended checks.
c. If none of the s
y
mptoms of Table A-2 appl
y
, proceed to
Table A-3. This table provides an initial troubleshootin
g
procedure that also directs
y
ou to the more detailed pro-
cedures which follow it.
The numbered test points referred to in the troubleshootin
g
procedures are identified on the circuit schematic at the rear
of the manual.
Open Fuse Troubleshooting
Althou
g
h transients or fati
g
ue can cause a fuse to blow, it is a
g
ood idea to inspect the unit for obvious shorts such as dam-
a
g
ed wirin
g
, charred components, or extraneous metal parts
or wire clippin
g
s in contact with circuit board conductors
before replacin
g
the fuse. The ratin
g
of the correct replace-
ment fuse depends on the line volta
g
e option of the instru-
ment: for Option OE3, use a slow-blow 1 amp fuse and
standard and Option OE9, use a slow-blow 2 amp fuse.
Table A-2. Miscellaneous Troubles
SYMPTOM CHECK - PROBABLE CAUSE
Hi
g
h ripple a. Check operatin
g
setup for
g
round loops.
b. Check main rectifiers(CR2, CR3, CR4) for open.
c. Suppl
y
ma
y
be operatin
g
in current limit mode. Check current limit adjustment, steps (l) thru (n)
on pa
g
e A-4.
Will not current limit Check for open OR-
g
ate diodes (CR9, CR21) or defective current limit amplifiers (U10, U19).
Poor load and line re
g
ulation a. Check bias and reference volta
g
es, Table A-4.
b. Check main rectifiers and filters for opens.
Oscillation or poor transient
response time a. Hi
g
h frequenc
y
oscillations (above 50 kHz) can be caused b
y
an open C13 or C35.
b. A defective output capacitor (C10 or C29) can cause oscillations in one of man
y
frequenc
y
ran
g
es.
c. Oscillation onl
y
in the current limitin
g
mode can be caused b
y
an open C34 or C12.
Excessive heat a. Check prere
g
ulator control circuit. Refer to Table A-7 and Table A-8.
b. Check Q3, Q4 and Q5 for short.
Output Volta
g
e clamped for
each output Check prere
g
ulator control circuit. Refer to Table A-7 and Table A-8.
Table A-3. Initial Troubleshootin
g
Procedure
STEP ACTION RESPONSE NEXT ACTION
1 Check output volta
g
e of V1
and V2 supplies. a. Zero volts
b. Output volta
g
e lower or
hi
g
her than ratin
g
a. Check ac line fuse (F1). If blown, proceed to "Open
Fuse Troubleshootin
g
" para
g
raph. If not blown, check
bias and reference volta
g
es (Table A-4).
b. Check bias and reference volta
g
es (Table A-4).

A-8
Table A-4. Output Volta
g
e Bias and Reference Volta
g
e Check
STEP ACTION RESPONSE NEXT ACTION
1 Check +12V bias. a. Normal (+12V ± 5%)
b. Volta
g
e hi
g
h
c. Output volta
g
e lower or
hi
g
her than ratin
g
a. Proceed to step (3).
b. Check U13(for V2 output) or U23(for V1 output) for
short.
c. Check U13(for V2 output) or U23(for V1 output) for
open.
Note: A short within U4,BU5, U6, U7, U9, U10, U18 or
U19 can cause low +12V or -12V bias volta
g
es.
2 Check -12V bias. a. Normal (-12V ± 5%)
b. Volta
g
e hi
g
h
c. Volta
g
e low
a. Proceed to step (4).
b. Check U14(for V2 output) or U20(for V1 output) for
open.
c. Check U14(for V2 output) or U20(for V1 output) for
short.
3 Check +5V reference. a. Normal (+5V ± 2%)
b. Volta
g
e hi
g
h
c. Volta
g
e low
a. Proceed to V1 suppl
y
troubleshootin
g
Table A-5.
b. Check U11(for V2 output) or U22(for V1 output) for
open.
c. Check U11(for V2 output) or U22(for V1 output) for
short.
4 Check -5V reference. a. Normal (-5V ± 2%)
b. Volta
g
e hi
g
h
c. Volta
g
e low
a. Proceed to V1 suppl
y
troubleshootin
g
Table A-5.
b. Check U12(for V2 output) or U21(for V1 output) for
open.
c. Check U12(for V2 output) or U21(for V1 output) for
short .
Table A-5. V1 Suppl
y
Troubleshootin
g
SYMPTOM STEP - ACTION RESPONSE PROBABLE CAUSE
Hi
g
h output volta
g
e
(hi
g
her than ratin
g
)1. Attempt to turn off Q2 b
y
shortin
g
emitter-to-col-
lector of Q10.
2. Measure volta
g
e at
base of Q10.
a. Output volta
g
e remains hi
g
h.
b. Output volta
g
e decreases.
a. Measured volta
g
e is more than 0
volt.
b. Measured volta
g
e is less than 0
volt.
a. Q1 shorted.
b. Remove short and proceed to step
(2).
a. Check for open CR8 or R48 and
check for defective U10B.
b. Check for defective Q6.
Low output volta
g
e
(lower than ratin
g
)1. Attempt to turn on Q2 b
y
disconnectin
g
emitter of
Q10.
2. Attempt to turn off of
Q10 b
y
shortin
g
point
to +12 V.
3. Eliminate current limit
circuit as a source of
troubleb
y
disconnectin
g
anode of CR9.
4. Measure volta
g
e at pin
3 of U10.
a. Output volta
g
e remains low.
b. Output volta
g
e increases.
a. Output volta
g
e remains low.
b. Output volta
g
e increases.
a. Output volta
g
e increases.
b. Output volta
g
e remains low.
a. Measured volta
g
e is near
+0.7V.
b. Measured volta
g
e is zero volt.
c. Measured volta
g
e is near
-0.7V
a. Q1 open.
b. Re-connect the emitter lead and
proceed to step (2).
a. Q6 shorted.
b. Remove short and proceed to step
(3).
a. Check for U10A defective.
b. Reconnect lead and proceed to
step (4).
a. Check for defective U10B.
b. Check for shorted CR14 and
CR15.
c. Check for shorted R48, or leak
y
or
shorted C9.

A-9
Table A-6. VTSuppl
y
Troubleshootin
g
SYMPTOM STEP - ACTION RESPONSE PROBABLE CAUSE
Hi
g
h output volta
g
e
(hi
g
her than ratin
g
)1. Attempt to turn off Q1 b
y
shortin
g
emitter-to-col-
lector of Q6.
2. Measure volta
g
e at
base of Q6.
a. Output volta
g
e remains hi
g
h.
b. Output volta
g
e decreases.
a. Measured volta
g
e is more than 0
volt.
b. Measured volta
g
e is less than 0
volt.
a. Q1 shorted.
b. Remove short and proceed to step
(2).
a. Check for open CR8 or R48 and
check for defective U10B.
b. Check for defective Q6.
Low output volta
g
e
(lower than ratin
g
)1. Attempt to turn on Q1 b
y
disconnectin
g
emitter of
Q6.
2. Attempt to turn off of Q6
b
y
shortin
g
point
to +12 V.
3. Eliminate current limit
circuit as a source of
troubleb
y
disconnectin
g
anode of CR9.
4. Measure volta
g
e at pin
3 of U10.
a. Output volta
g
e remains low.
b. Output volta
g
e increases.
a. Output volta
g
e remains low.
b. Output volta
g
e increases.
a. Output volta
g
e increases.
b. Output volta
g
e remains low.
a. Measured volta
g
e is near
+0.7V.
b. Measured volta
g
e is zero volt.
c. Measured volta
g
e is near
-0.7V
a. Q1 open.
b. Re-connect the emitter lead and
proceed to step (2).
a. Q6 shorted.
b. Remove short and proceed to step
(3).
a. Check for U10A defective.
b. Reconnect lead and proceed to
step (4).
a. Check for defective U10B.
b. Check for shorted CR14 and
CR15.
c. Check for shorted R48, or leak
y
or
shorted C9.
Table A-7. V1 Prere
g
ulator/Control Circuit Troubleshootin
g
STEP ACTION RESPONSE PROBABLE CAUSE
Set output volta
g
e at 16V.
1 Measure the volta
g
e for pin 7 of U18. a. Measured volta
g
e is -12V.
b. Measured volta
g
e is near
+11.3V.
a. Proceed to step (2).
b. Check for defective U18B.
2 Measure the volta
g
e for pin 1 of U3. a. Measured volta
g
e is near +1V
b. Measured volta
g
e is near 0V. a. Check for defective U3 or Q5. b. Check for open Q9 or R6.
Table A-8. V2 Prere
g
ulator/Control Circuit Troubleshootin
g
STEP ACTION RESPONSE PROBABLE CAUSE
Set output volta
g
e to 10V ± 1V.
1 Measure the volta
g
e for pin 1 of U4. a. Hi
g
h volta
g
e(+0.7 V).
b. Low volta
g
e(0 V). a. U1 or Q3 defective. b. Proceed to step 2.
2 Measure the volta
g
e for pin 1 of U6. a. Low volta
g
e(-12 V).
b. Hi
g
h volta
g
e(+12 V). a. U4 defective. b. Proceed to step 3.
3 Measure the volta
g
e for pin 1 of U7. a. Hi
g
h volta
g
e(+12 V).
b. Low volta
g
e(-12 V). a. U6 defective. b. Proceed to step 4.
4 Measure the volta
g
e from pin 6 to pin
7 of U7. a. Measured volta
g
e is positive.
b. Measured volta
g
e is ne
g
ative. a. U7 defective. b. U5 defective.
Set output volta
g
e to 19V ± 1V.
5 Measure the volta
g
e for pin 7 of U4. a. Hi
g
h volta
g
e(+0.7 V).
b. Low volta
g
e(0 V). a. U2 or Q4 defective. b. Proceed to step 6.

A-10
6 Measure the volta
g
e for pin 14 of U6. a. Low volta
g
e(-12 V).
b. Hi
g
h volta
g
e(+12 V). a. U4 defective. b. Proceed to step 7.
7 Measure the volta
g
e for pin 14 of U7. a. Hi
g
h volta
g
e(+12 V).
b. Low volta
g
e(-12 V). a. U6 defective. b. Proceed to step 8.
8 Measure the volta
g
e from pin 8 to pin 9 of
U7. a. Measured volta
g
e is positive.
b. Measured volta
g
e is ne
g
ative. a. U7 defective. b. U5 defective.
Table A-8. V2 Prere
g
ulator/Control Circuit Troubleshootin
g
(Cont’d)

A-11
ADJUSTMENT AND CALIBRATION
Current Limit Adjustment
To adjust the current limit circuit in the V1 or V2 supply, pro-
ceed as follows:
a. Turn the current limit adjustment pot (R63 for V1 supply
or R34 for V2 supply) to fully counter clockwise.
b. Connect the test setup shown in Fi ure A-6 to the output
of the supply to be adjusted. Substitute a short for RL and
leave load circuit switch open.
c. Turn on the supply and set the VOLTAGE control for max-
imum output(fully clockwise).
d. Close load switch and adjust the current limit pot (R63 or
R34) until the DVM indicates a volta e drop across the
shunt of 0.1 V + 5% (0.105 V).
Meter Calibration
Voltmeters. To calibrate voltmeter, proceed as follows:
a. Connect DVM across V1 + and - output terminal.
b. Turn on the supply and push V1 METER switch in.
c. Set the output volta e to 17.00 volts, and adjust R16 on
the display board until front panel VOLTS display reads
exactly DVM value. Next, set the output volta e to 25.0
volts and adjust R17 on the display board until front panel
VOLTS display reads exactly DVM value.
d. To calibrate the voltmeter for V2 output, push V2 METER
switch in and connect DVM across V2 + and - output ter-
minal.
e. Set the output volta e to 15.00 V and then adjust R81 on
the main board until front panel VOLTS display reads
exactly DVM value.
Ammeters. To calibrate ammeter for V1 and V2 supplies,
proceed as follows:
a. Connect the test setup shown in Fi ure A-6 to the output
of the V1 supply. Substitute a short for RL and leave load
circuit switch open.
b. Push V1 METER switch in and turn V1 VOLTAGE control
fully clockwise.
c. Close the load switch and adjust R5 on the display board
until front panel AMPS display reads exactly DVM value
divided by RS.
d. To calibrate the ammeter for V2 output, repeat step (a) to
the V2 supply. Select V2 METER switch and turn V2
VOLTAGE control fully clockwise.
e. Adjust R80 on the main board until front panel AMPS dis-
play reads exactly DVM value divided by Rs.
REPLACEABLE PARTS
INTRODUCTION
This section contains information for orderin replacement
parts. Table A-11 lists parts by reference desi nators and pro-
vides the followin information:
a. Reference desi nators. Refer to Table A-9.
b. A ilent Technolo ies Part Number.
c. Total quantity used in that assembly.
d. Description.
e. Manufacturer's supply code number. Refer to Table A-
10 for manufacturer's name and address.
f. Manufacturer's part number or type.
Mechanical and miscellaneous parts are not identified by ref-
erence desi nator.
ORDERING INFORMATION
To order a replacement part, address order or inquiry to your
local A ilent Technolo ies sales office (see lists at rear of this
manual for addresses). Specify the followin information for
each part: Model, complete serial number of the power sup-
ply; A ilent Technolo ies part number; circuit reference des-
i nator; and description.
Table A-9. Reference De ignator
A Assembly
C Capacitor
CR Diode
DS Si nalin Device(li ht)
FFuse
G Pulse Generator
JJack
L Inductor
Q Transistor
RResistor
SSwitch
T Transformer
TP Test Point
VR Zener Diode
U Inte rated Circuit
WWire
Table A-10. Code Li t of Manufacturer
C DE MANUFACTURER ADDRESS
01295 Texas Instruments Inc, Semicon Comp Div. Dallas, TX
14936 General Instruments Corp, Semicon Prod Hicksville, N.Y.
27014 National Semiconductor Corporation Santa Clara, CA
28480 A ilent Technolo ies Palo Alto, CA
04713 Motorola Semiconductor Products Phoenix, AZ
32997 Bourns Inc. Riverside, CA

Table A-11. Replaceable Parts List
REFERENCE
DESIGNATE Agilent PART NUMBER Q'TY DESCRIPTION MFR. CODE MFR. P/N
8120-8767 1 POWER CORD FOR STD,0E9 28480
8120-8768 1 POWER CORD FOR 0E3 28480
E3620-60001 1 MAIN BODY ASSY (STD, 0E9) 28480
E3620-60005 1 MAIN BODY ASSY (0E3) 28480
5041-8622 1 COVER 28480
0371-3806 1 KEY CAP - WHT 28480
E3630-40007 2 KEY CAP - FLINT RAY 28480
0340-0140 2 INSULATOR - TRANSISTOR MICA 28480
0340-0168 8 INSULATOR BUSHIN 28480
Q1,2 1854-0611 2 TRANSISTOR NPN 2N6056 SI DARL TO 304713 2N6056
E3620-60003 1 HEAT SINK ASSY-STD,0E9(115V, 100V) 28480
E3620-60006 1 HEAT SINK ASSY-0E3(230V) 28480
1252-4214 1 AC INLET SOCKET 28480
2110-0702 1 FUSE 2A 250V NTD (STD,0E9) 28480
2110-0457 1 FUSE 1A 250V NTD (0E3) 28480
5022-1632 1 HEATSINK-DIECASTIN 28480
E3620-60004 1 FRONT PANEL ASSY 28480
E3620-60009 1 DISPLAY BOARD ASSY 28480
R48,74 2100-4503 2 RES-VAR 10K 5% 10-TURN WW 32997 3590S-A7-103
E3631-20011 2 BINDIN POST RED 28480
E3631-20012 2 BINDIN POST BLACK 28480
E3631-20013 1BINDIN POST REEN 28480
2950-0144 5 NUT- BINDIN POST 28480
5041-8621 2 KNOB 28480
E3620-60002 1 MAIN BOARD ASSY 28480
E3620-20001 1 PCB MAIN FOR E3620A 28480
C24 0180-4360 1 CAP-FXD 1000UF +- 20% 25V AL-ELECTLT 28480
C22,23,31 0180-4085 3 CAP-FXD 330UF +-20% 35V AL-ELECTLT 28480
C19,20,25,26,32,33 0160-7449 6 CAP-FXD .33UF +-10% 50V POLYP-MET 28480
C17,18,27,28,40,41 0180-3970 6 CAP-FXD 1UF +-20% 50V AL-ELECTLT 28480
C10,21,29,30 0180-4355 4 CAP-FXD 470UF 50V +-20% AL-ELECTLT 28480
C42 0160-4065 1 CAP-FXD 0.1UF +-20% 250V PPR-MET 28480
C7,8,11,12,15,16,34,36,39 0160-4832 9 CAP-FXD 0.01UF +-10% 100V CER 28480
C1,2,5,6 0180-3657 4 CAP-FXD 1000UF +-20% 63V AL-ELECTLT 28480
C3,4 0160-6225 2 CAP-FXD 0.33UF +-10% 250V POLYP-MET 28480
C9,37 0180-3769 2 CAP-FXD 6.8UF +-10% 35V TA 28480
C13,14,35,38 0160-4801 4 CAP-FXD 100PF +-5% 100V CER 28480
C43,44 0160-7049 2 CAP-FXD 4700PF +-20% 250V CER X5V 28480
R51 0699-2715 1 RESISTOR-FUSE 1OHM +-5%; 0.5W @70 28480
R54 0757-0401 1 RESISTOR 100 +-1%; 0.125W TF TC=0 +-100 28480
R52 0698-4440 1 RESISTOR 3.4K +-1%; 0.125W TF TC=0 +-100 28480
R53 0698-4425 1 RESISTOR 1.54K +-1%; 0.125W TF TC=0 +-100 28480
R18,19,20,62 0698-8824 4 RESISTOR 562K +-1% 0.125W TF TC=0 +-100 28480
R13,14,15,16,17,27,36,37,61 0757-0442 9 RESISTOR 10K +-1%; 0.125W TF TC=0 +-100 28480
A-12