Test Equipment Depot 1332A User manual
TABLE OF CONTENTS
GENERAL INFORMATION............................ Page 1
SPECIFICATIONS......................................... Page 2
LOCATION AND DESCRIPTION OF
OPERATING CONTROLS.............................. Page 4
INSTALLATION.............................................. Page 5
OPERATING INSTRUCTIONS....................... Page 6
POWER SUPPLYOPERATION .................... Page 8
SAFETY INSTRUCTION ............................... Page 9
OPERATING PRECAUTIONS........................ Page 10
CASE DISASSEMBLY AND ASSEMBLY....... Page 11
MAINTENANCE AND RECALIBRATION........ Page 11
SERVICE AND WARRANTY INFORMATION. Page 12
PARTLIST.................................................... Page 13
SCHEMATIC AND BOARD LAYOUT.............. Page 20
LIST OF ILLUSTRATIONS
FIGURE 1. Location of operating controls...... Page 4
PCB Components Z-TR/01 PCB REV - 01
=======================================================================
Ref Designator Value
=======================================================================
RESISTORS
R1 1K,2W,5%,MOR
R2 0.1E,2.5W,5%,WW
R129* 33K,0.25W,5%,MFR
CAPACITORS
C1 0.1uF,50V,CD
C2 100uF,50V,EL
C3 10uF,50V,EL
DIODE
CR1 1N5402 X 2
PCB Components CHASSIS & FRONT PANELS
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Ref Designator Value
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CHASSIS
VARISTOR FOR 115V - 201K
FOR 230V - DNR 20D 361
FILTER YUNPEN EMI 6A/125V/250V
MAINS TRANSFORMER 650VA
INPUT FUSE FOR 115V - 5Amp TYPE T
FOR 230V - 2.5Amp TYPE T
FRONT PANEL
WW POT 1KE 1W X 2
WW POT 10KE 1W
WW POT 50E 1W
LED GREEN 3mm
LED RED 3mm
ON/OFF SWITCH DPST CHILLY3022 6A /125V/250V
19
GENERAL INFORMATION
DESCRIPTION
The 1332A Power Supply is a high perfomance single
output DC power supply for industrial and laboratory
use. Performance with economy have successfully
been combined to provide a compact, fully solid state
instrument.
The output is continuously variable from 0 to 32V and can
supply 5A max, and can be adjusted continuously through-
out the output range. The front panel CURRENT control
can be used to establish the output current limit (overload
or short circuit). When the supply is used as a constant
voltage source the VOLTAGE controls can be used to limit
the output voltage. When the unit is used as a constant
current source, CURRENT controls can be used to limit
the output current. The unit will automatically cross over
from constant voltage to current mode and vice-versa, if
the output current or voltage exceeds these preset lim-
its. Output voltage and current are continuously moni-
tored on two front panel meters.
The load terminals are provided on the front panel. Either
the positive or negative output terminal may be grounded
or the power supply can be operated floating at upto a
maximum of ±300VDC above ground.
All the outputs are floating i.e. neither the output positive
terminal nor the negative terminal (nor any point within the
regulator circuitry) is connected to ground.
The power supply is designed to operate in ambient
temperature of upto 40°C and full output may be drawn
continuously provided free air circulation is allowed.The
unit works from mains supply of 115V/230VAC, 47-63 Hz
with selectable Switch.
1
PCB Components 2 X Z-DPM/01 PCB REV - 01
=======================================================================
Ref Designator Value
=======================================================================
RESISTORS
R1 39K,0.25,5%,MFR
R2 470K,0.25W,5%,MFR
R3 1M,0.25W,5%,MFR
R4* SEL(INPUT)
R5 10K,0.25W,5%,MFR
R6 2K4,0.25W,5%,MFR
R7 330E,0.25W,5%,MFR
R8 330E,0.25W,5%,MFR
R9 6K8, 0.25W,5%,MFR
PRESETS
PR1 2.5K,LIN,VER (REF ADJ)
CAPACITORS
C1 220pF,50V,CD
C2 0.1uF,100V,MP
C3 0.01uF,50V,CD
C4 0.47uF,100V,MP
C5 0.1uF,100V,MP
C6 0.1uF,100V,MP
C7 10uF,50V,EL
C8 0.1uF,50V,CD
C9 10uF,50V,EL
C10 0.1uF,50V,CD
IC’s
IC1 7107 DECODER DRIVER
VR1 TL - 431
FND’s
DS1 TSD566 GREEN
DS2 TSD566 GREEN
DS3 TSD566 GREEN
LED’s
LED1* 3MM GREEN(VOLTAGE) FOR 'CV' MODE
LED2* 3MM RED (CURRENT) FOR 'CC' MODE
MISCILLANEOUS
J1 2.54PITCH,3PIN M
J2 NOT USED.
J3 2.54PITCH,4PIN M
18
SPECIFICATIONS
Detailed specifications of the power supply are given in the
following table.
OUTPUT VOLTAGE :0-32V DC continuously variable
with coarse and fine voltage
controls
LOAD CURRENT :0-5 Amp max., continuously
variable with coarse and fine
controls
CONSTANT VOLTAGE MODE
REGULATION
LINE :Less than ± 0.01% +2mV for
±10% change in line voltage.
LOAD :Less than ± 0.01% + 2mV for load
change from zero to full load.
RIPPLE & NOISE : Less than 1mV rms max.
( 20Hz - 20MHz )
CONSTANT CURRENT MODE
REGULATION
LINE :Less than ± 0.1% +250µA
for ±10% change in line
voltage.
LOAD : Less than ±0.1% +250µA
for change in output voltage
from 0 volts to max.output
voltage.
RIPPLE & NOISE : 0.04% rms.(2.0 mA )
OUTPUT POLARITY : Floating w.r.t. ground.
OVERLOAD PROTECTION :Automatic overload and
short circuit protection.
TRANSIENT RESPONSE : 100µsecs to within 10mV of
set output voltage for load
change from 10% to 90%.
2
PCB Components ZSDT-CT/05 PCB
=======================================================================
Ref Designator Value
=======================================================================
ZENERS
Z1 1N758, 10V, 0.4W
Z2 1N758, 10V, 0.4W
Z3 1N750, 4.7V, 0.4W
BRIDGE
BR1 10A/600V PC MTG BRIDGE
BR2 CSB-1, 100V/1A BRIDGE.
ICs
IC1 4N25 OPTO
IC2 7812
IC3 TL431
IC4 LM324
IC5 7812
IC6 TL431
IC7 79L05
IC8 7805
TRANSISTORS/FET/SCR
Q1 BC109
Q2 MPSA12
Q3 BC557
Q4 BC557
Q5 BC547
FET1 IRFP150
SCR1 2N6396
FET2 IRFP150
CONNECTORS
CON2 2.54mm PITCH, 12PIN M
CON3 2.54mm PITCH, 12PIN M L TYPE
CON4 2.54mm PITCH, 8PIN M
MISCELLANEOUS
TP1 RIM PIN MALE
TP2 RIM PIN MALE
TP3 RIM PIN MALE
TP4 RIM PIN MALE
TP5 RIM PIN MALE
TP6 RIM PIN MALE
SPADE CON 12H750
17
STABILITY
Total drift within 8 hours, : ±0.1% +2.5mV in constant
voltage mode.
after warm up under :±0.5% +2mA in constant
current mode.
constant line,load & temp.
PANEL METERS :Digital panel meters
(marked V for voltmeter
and A for ammeter) are
provided with an accuracy
of ± 3 counts.
MODE INDICATION :Respective LED lights up
when the unit is working
in CV or CC mode.
OUTPUT CONTROLS : Single turn coarse and fine
voltage and current
controls are provided on
the front panel
OPERATING TEMP.: 0-40°C.
INPUT VOLTAGE : 115V / 230V AC, ± 10%,
47 - 63Hz single phase
DIMENSIONS ( W x D x H ) : 230mm x255mm x133mm
WEIGHT :9.0Kg. nett. Approx.
3
PCB Components ZSDT-CT/05 PCB
=======================================================================
Ref Designator Value
========================================================================
C20 220µF/50V, ELE
C21 47µF/50V, ELE
C22 10µF/50V, ELE
C23 0.1µF/50V, CD
C24 10µF/50V, ELE
C25 10µF/50V, ELE
C26 0.1µF/50V, CD
C27 470µF/50V, ELE
C29 1000µF/35V,ELE
DIODES
CR1 Not Used
CR2 1N4007, 1KV/1A
CR3 1N4007, 1KV/1A
CR4 1N4007, 1KV/1A
CR5 1N4007, 1KV/1A
CR6 1N4007, 1KV/1A
CR7 1N4007, 1KV/1A
CR8 1N4007, 1KV/1A
CR9 1N4007, 1KV/1A
C10 1N4007, 1KV/1A
CR111N4007, 1KV/1A
CR12 1N4007,1KV/1A.
CR13 1N4007,1KV/1A.
CR14 1N4007,1KV/1A
CR15 1N4007,1KV/1A
CR16 1N4007, 1KV/1A
CR17 1N4007, 1KV/1A
CR18 1N4007, 1KV/1A
CR19 1N4007, 1KV/1A
CR20 1N4007, 1KV/1A
CR21 1N4007, 1KV/1A
CR22 1N4007, 1KV/1A
CR23 1N4007, 1KV/1A
CR24 1N4007, 1KV/1A
CR25 1N4148, 100V/10mA
CR26 1N4148, 100V/10mA
CR27 1N4148, 100V/10mA
CR28 1N4148, 100V/10mA
CR29 1N4007, 1KV/1A
CR30 1N4007, 1KV/1A
16
LOCATION AND DESCRIPTION OF
OPERATING CONTROLS
In order to use the full capabilities of the 1332A, it is highly
recomended that the user become familiar with the
controls associated with this instrument. (See Figure 1)
Figure 1. Location of operating controls.
1-Power ON/OFF switch. 7-Current Fine Control Clockwise
rotation increases variable output
current in CC mode.
2-Supply LED Display.8-CV LED
Display Voltage 0 to 32VDC Constant Voltage mode Indication
3-Supply LED Display.9-CC LED
Displays current 0 to 5AMP.Constant Current Mode Indication
4-Variable coarse voltage control. 10-Output terminals
Clockwise rotation increases Red terminal is output (+)ve.
variable o/p voltage in CV mode. Black terminal is output (-)ve.
5-Variable fine voltage control. 11-Ground terminal.
Clockwise rotation increases
variable output voltage in CV mode.
6-Current coarse Control.
Clockwise rotation increases variable
output current in CC mode.
4
PCB Components ZSDT-CT/05 PCB
=======================================================================
Ref Designator Value
========================================================================
R37 2K, MFR, 1/4W, 5%
R38 1K, MFR, 1/4W, 5%
R39 1K, MFR, 1/4W, 5%
R40 4.7K, MFR, 1/4W, 5%
R41 330K, MFR, 1/4W, 5%
R42 100E, MFR, 1/4W, 5% (I CAL)
R43* 3.9K, MFR, 1/4W, 5% (I CAL)
R44 1K, MFR, 1/4W, 5%
R45 1K, MFR, 1/4W, 5%
R46* 10K, MFR, 1/4W, 5% (V CAL)
R47* 100E, MFR, 1/4W, 5% (V CAL)
R48 2K, MFR, 1/4W, 5%
R49 Shorting Link
R50 Shorting Link
R51 10E, MFR, 1/4W, 5%
R59 10E, MOR, 2W
PRESETS
PR101 5K, PRE, LIN, (V)(DEV. DROP)
PR102 500E, PRE, LIN, (V)(V CAL)
PR103 500E, PRE, LIN, (V)(I CAL)
CAPACITORS
C1 0.1µF/100V, MP
C2 0.1µF/250VAC MKP
C3 15,000µF/50V ELE
C4 0.1µF/50V, MP 10%
C5 33µF/50V, ELE
C6 100µF/50V, ELE
C7 100µF/50V, ELE
C8 1µF/50V, ELE
C9 4.7µF/50V, ELE
C10 10µF/50V, ELE
C11100µF/50V, ELE
C12 47µF/50V, ELE
C13 1kpF/50V, CD
C14 1kpF/50V,.CD
C15 0.1µF/50V, CD
C16 10µF/50V, ELE
C17 10µF/50V, ELE
C18 0.1µF/50V, CD
C19 220µF/50V, ELE
15
INSTALLATION
INITIAL INSPECTION : As soon as the power supply
unit is unpacked inspect for any damage that may have
occured during transit. Save all packing material until in-
spection is completed. If any damage is found, notify the
carriers immediately. Our authorised representatives should
also be notified.
PHYSICAL 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
the meters are not scratched and cracked.
ELECTRICAL CHECK : The power supply unit should
be checked against electrical specifications.An in-cabinet
performance check will verify proper operation.
INSTALLATION DATA : The power supply unit is shipped
ready for bench operation. It is necessary only to connect
the unit to a rated source of power and it is ready for opera-
tion.
LOCATION : The power supply unit is naturally
cooled.Sufficient space should be kept around the unit while
in operation, so that heat sinks do not remain in confined
space or close to another heating source.The ambient tem-
perature of the area around the unit should be less than
40°C.
INPUT POWER REQUIREMENTS : The power supply
unit may be operated continuously from input voltage of 115V
/ 230V 47-63Hz power source with selectable Switch.
REPACKAGING FOR SHIPMENT : To ensure safe ship-
ment of the power supply unit, it is recommended that the
package designed for the unit be used. The original pack-
aging material is reusable. Be sure to attach a tag to the
unit specifying the owner, and the fault observed with a brief
description.
REMOVING COVER : The top cover is retained in place
by 6 self tapping screws & two handle mounting screws.
To remove cover, proceed as follows :
a) Remove the handle mounting screws.
b) Remove the self tapping screws on sides.
c) Lift the cover from rear side, slide backwards & pull.
5
PCB Components ZSDT-CT/05 PCB
=======================================================================
Ref Designator Value
========================================================================
R37 2K, MFR, 1/4W, 5%
R38 1K, MFR, 1/4W, 5%
R39 1K, MFR, 1/4W, 5%
R40 4.7K, MFR, 1/4W, 5%
R41 330K, MFR, 1/4W, 5%
R42 100E, MFR, 1/4W, 5% (I CAL)
R43* 3.9K, MFR, 1/4W, 5% (I CAL)
R44 1K, MFR, 1/4W, 5%
R45 1K, MFR, 1/4W, 5%
R46* 10K, MFR, 1/4W, 5% (V CAL)
R47* 100E, MFR, 1/4W, 5% (V CAL)
R48 2K, MFR, 1/4W, 5%
R49 Shorting Link
R50 Shorting Link
R51 10E, MFR, 1/4W, 5%
R59 10E, MOR, 2W
PRESETS
PR101 5K, PRE, LIN, (V)(DEV. DROP)
PR102 500E, PRE, LIN, (V)(V CAL)
PR103 500E, PRE, LIN, (V)(I CAL)
CAPACITORS
C1 0.1µF/100V, MP
C2 0.1µF/250VAC MKP
C3 15,000µF/50V ELE
C4 0.1µF/50V, MP 10%
C5 33µF/50V, ELE
C6 100µF/50V, ELE
C7 100µF/50V, ELE
C8 1µF/50V, ELE
C9 4.7µF/50V, ELE
C10 10µF/50V, ELE
C11100µF/50V, ELE
C12 47µF/50V, ELE
C13 1kpF/50V, CD
C14 1kpF/50V,.CD
C15 0.1µF/50V, CD
C16 10µF/50V, ELE
C17 10µF/50V, ELE
C18 0.1µF/50V, CD
C19 220µF/50V, ELE
14
OPERATING INSTRUCTIONS
TURN ON SETTING PROCEDURE
The following procedure describes the use of controls and
indicators.
a.Ensure that the AC power switch is in the "OFF"
position.
b.Connect the unit to a specified input voltage.
c. Turn the VOLTAGE and CURRENT controls fully
counter-clockwise.
d.Set ‘POWER ON’ Switch to "ON" position,The front
panel digital meters will light up and voltmter and
ammeter displays will read zero,and observe that
CV LED glows.
e.Adjust the ”VOLTAGE” controls till the desired
voltage is indicated on voltmeter.
f. To check "CONSTANT CURRENT" mode, turn
OFF the supply. Short circuit the output terminals
of the power supply and turn ON the supply.
g. Adjust 'CURRENT' controls until the desired out
put current is indicated on ammeter. Also check
that the CC LED glows.
h. Remove the short circuit.
CONSTANT VOLTAGE MODE :
To select a constant voltage output, proceed as follows :
a.Connect a digital voltmeter (DVM) across the out
put terminals, observing correct polarity. The DVM
must be rated for better than 0.5% accuracy.
b. Turn the CURRENT controls clockwise. And
Slowly If a load change causes the current limit
to be exceeded, the power supply will automati
cally cross over to constant current output at cur
rent limit and output voltage will drop proportion
ately. In setting the current limit, allowance must
be made for high peak currents which can cause
unwanted crossover.
SECTION 5
PART LIST & SCHEMATICS
PCB Components ZSDT-CT/05 PCB
=======================================================================
Ref Designator Value
========================================================================
RESISTORS
R1 270E, 2W, 5%, MOR
R2 47E, MFR, 1/4W, 5%
R3 10K, MFR, 1/4W
R4* 1K, MFR, 1/4W, 5%
R5 10E, MFR, 1/4W, 5%
R6 3.9K, MFR, 1/4W
R7 3.3K, 2W, 5%, MOR
R8 10K, MFR, 1/4W
R9 8.2K, MFR, 1/4W
R10 100K, MFR, 1/4W
R114.7E, MFR, 1/4W.
R12 1.5K, MFR, 1/4W.
R13 180K, MFR, 1/4W.
R14 390E, MFR, 1/4W.
R15 6.8K, MFR, 1/4W, 5%
R16 12K, MFR, 1/4W, 5%
R17 3.9K, MFR, 1/4W, 5%
R18 10K, MFR, 1/4W
R19 10K, MFR, 1/4W
R20 10K, MFR, 1/4W
R21 3.3K, 2W, 5%, MOR
R22 270E, 2W, 5%, MOR
R23# 82K, MFR, 1/4W, 5%
R24 4.7K, MFR, 1/4W, 5%
R25 24E, MFR, 1/4W, 5%
R26 820E, MFR, 1/4W, 5%
R27# 330K, MFR, 1/4W, 5%
R28# 39K, MFR, 1/4W, 5%
R29# 180K, MFR, 1/4W, 5%
R30 1K, MFR, 1/4W, 5%
R31 15E, MFR, 1/4W, 5%
R32 6.8K, MFR, 1/4W, 5%
R33 15K, MFR, 1/4W, 5%
R34 6.8K, MFR, 1/4W, 5%
R35 15K, MFR, 1/4W, 5%
R36 1K, MFR, 1/4W, 5%
13 6
7
SERVICE AND WARRANTY INFORMATION
FACTORYSERVICE AND REPAIR :
Global Specialties will service and repair this instrument
free of charge for a period of one full year subject to the
warranty conditions stated below.
To obtain a return merchandise authorisation (RMA)
required for all returns, phone our customer service
department for a RMA and all shipping instructions :
ATTN : Customer Service Department
WARRANTY
Global Specialties warrants this device to be free from
defective material or workmanship for a period of 3 years
from the date of original purchase.
Global Specialties under this warranty is limited to repairing
the defective device when returned to the factory,shipping
charges prepaid, within three full years from the date of
original purchase.
Units returned to Global Specialties that have been
subject to abuse, misuse, damage or accident or have been
connected, installed or adjusted contrary to the instructions
furnished by Global Specialties, or that have been repaired
by unauthorised persons will not be covered by this
warranty.
Global Specialties reserves the right to discontinue models,
change specifications ,price or design of this device at any
time without incurring any obligation whatsoever.
The purchaser agrees to assume all liabilities for any
damages and/or bodily injury which may result from the use
or misuse of this device by the purchaser his employees or
agents. This warranty is in lieu of all other representations
or warranties expressed implied and no agent or
representitive of Global Specialties is authorised to assume
any other obligation in connection with the sale and purchase
of this device.
12
CONSTANT CURRENT MODE :
To select a constant current output, proceed as follows :
a. Short circuit the output terminals of the power supply.
b. Connect a DC Ammeter OR a shunt-digital voltmeter
(DVM) combination across the output terminals,
using appropriately-guaged wire and hardware. The
recommended current ratings for the ammeter or
he shunt and the wire must be at least 10% more
than the output current of the power supply model.
The ammeter or shunt-DVM combination must be
rated better than 0.5% accuracy.
c. Turn the VOLTAGE controls clockwise. And Turn the
CURRENT controls slowly clockwise. The CURRENT
control range will be from minimum to maximum
rated output current. Adjust CURRENT controls for
desired output current.
d. Compare the ammeter reading with the front panel
ammeter reading. Or, compare the DVM reading with
the front panel ammeter reading using I = V/R, where
V is the DVM reading and R is the DC shunt
resistance.
e. Open output terminals and adjust VOLTAGE
controls for maximum output as required by the load
conditions.
If a load change causes the voltage limit to be
exceeded, the power supply will automatically cross
over to constant voltage output at the preset voltage
limit and output current will drop proportionately. In
setting voltage limit, allowance must be made for
high peak voltages which can cause unwanted
crossover. Turn the VOLTAGE controls clockwise and
observe both the front panel voltmeter and the
DVM. Compare the DVM reading with the front
panel voltmeter reading to verify the accuracy of the
internal voltmeter
c.The VOLTAGE control range will be from minimum
to the maximum rated output voltage. Adjust desired
voltage by adjusting the voltage controls.
d. Short circuit output terminals and adjust CURRENT
controls for maximum output current as required by
the load conditions.
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
8
CASE DISASSEMBLY AND ASSEMBLY
WARNING
Potentially lethal AC power is present whenever theline
cord is plugged into the AC outlet,even when the power
switch is OFF.Always disconnect the power cord when
opening the case. Avoid touching the fuse post on
the inside of the unit.
Should access to the inside of the unit be required,
proceed as follows
1. Remove the line cord from the AC outlet before
disassembly
2. To disassemble the case,remove the screws that
secure the cover to the chassis and lift the cover off.
3. To reassemble the case, place the cover on the
chassis, line up the screw holes, and replace the
screws.
MAINTENANCE AND RECALIBRATION
ADJUSTMENTS :
All circuitry is factory -calibrated. No user adjustments are
required.
FUSE REPLACEMENT :
Remove the line cord from the AC outlet before changing
fuses. Using the screwdriver, remove the fuse holder
cap. Replace the fuse with another of identical type and
current rating. Replace the fuse holder cap.
11
If a load change causes the current limit to be exceeded,
the power supply will automatically cross over to constant
current output at current limit and output voltage will drop
proportionately. In setting the current limit, allowance must
be made for high peak currents which can cause unwanted
crossover.
CONSTANT CURRENT MODE :
To select a constant current output, proceed as follows :
a. Short circuit the output terminals of the power supply.
b. Connect a DC Ammeter OR a shunt-digital voltmeter
(DVM) combination across the output terminals,
ing appropriately-guaged wire and hardware. The
recommended current ratings for the ammeter or
the shunt and the wire must be at least 10% more
than the output current of the power supply model.
The ammeter or shunt-DVM combination must be
rated better than 0.5% accuracy.
c. Turn the VOLTAGE controls clockwise. And Turn the
CURRENT controls slowly clockwise. The CURRENT
control range will be from minimum to maximum
rated output current. Adjust CURRENT controls for
desired output current.
d. Compare the ammeter reading with the front panel
ammeter reading. Or, compare the DVM reading with
the front panel ammeter reading using I = V/R, where
V is the DVM reading and R is the DC shunt
sistance.
e. Open output terminals and adjust VOLTAGE
controls for maximum output as required by the load
conditions.
If a load change causes the voltage limit to be
exceeded, the power supply will automatically cross
over to constant voltage output at the preset voltage
limit and output current will drop proportionately. In
setting voltage limit, allowance must be made for
high peak voltages which can cause unwanted
crossover.
9
OPERATING PRECAUTIONS
The power supply is ideally suited for virtually any type
of IC bread boarding from TTL, CMOS and ECL to
op-amps, audio and video amps, phase locked loops, and
microprocessor circuitry. However,certain normal bread
boarding precautions should be taken to avoid ground
loops and inadvertent loading. Observance of correct load
polarity is also important since most ICs may be damaged
by improper power supply connections.
POLARITY :
Observe proper polarity when connecting the power
supplies to the load, especially if the load is polarity
sensitive and does not have reverse polarity protection.
GROUND LOOPS :
A ground loop is a voltage drop on a ground bus caused
by a power stage output entering the ground bus some
distance away from the power supply ground binding post.
This small voltage drop, though only milliVolts or micro
Volts, is a part of the output load. If a preamplifier input of
circuit ground is connected to a portion of this ground bus,
feedback and oscillation may occur. To prevent this all
output stages should be positioned as close as possible
to the ground terminal,preamps farther away. Many audio
IC's have seperate input and output grounds to prevent
ground loops.
Eventhough power supplies are tightly regulated, a short
length of a power bus can present enough inductance to
cause linear IC oscillation at high frequencies. For this
reason, effective bypass capacitors are needed to bypass
the power buses. Place these capacitors as close as
possible to the power supply pins of the IC.Disc ceramics
(0.1µF ) work well and should be placed across as many
ICs as possible. Do not use elec trolytic or paper
capacitors because they have high inductances and cease
to act as bypasses above one or two MHz. Bypassing is
required with digital IC's also; problems such as inability
to reset or to clear and false triggering can occur if IC's are
not properly bypassed.
10
LOAD CONNECTIONS :
The load should be connected to the power supply output
terminals using separate pairs of connecting wires. This
will minimize mutual coupling effects between loads and
will retain full advantage 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 reduce
noise pick up. (If a shielded pair is used, connect one end
of the shield to ground at power supply and leave the other
end unconnected).
Positive or negative voltage can be obtained from this
supply by grounding either one of the output terminals or
one end of the load. Always use two leads to connect
load to the supply, regardless of where the set up is
grounded. This will eliminate any possibility of the output
current return paths through the power source ground
which would damage the line cord plug. This supply can
also be operated upto ±300V DC above ground, if neither
output terminal is grounded.
POWER SUPPLYOPERATION
INITIAL SET UP :
Refer to the preceding section for initial set up of the power
supply.
OPERATING INSTRUCTIONS :
Proper operation of most circuitry depends on correct
supply voltages. It is recommended that the power supply
be set to the required voltage levels with the load
disconnected. When the desired voltage is set (using the
variable voltage control),turn the AC power OFF, connect
the load to the power supply. then turn the AC power ON.
Output voltage and current of the power supply may be
read on the separate digital panel meters continuously.
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