Lambda LJS-13A Series User manual

/A\ LAMBDA
LAMBDA ELECTRONICS-MELVILLE, L. I., N. Y.

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This manual provides instructions intended for the operation of Lambda power supplies, and is not to be
reproduced without the written consent of Lambda Electronics. All information contained herein applies
to all LJS-13A models unless otherwise specified.
LAMBDA ELECTRONICS MELVILLE, L.I. N.Y.
MAIN PLANT TELEPHONE: 516 MYrtle 4-4200
IM-LJS-13A
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Performance Checks he
Adjustment of Calibration Control VR2
SERVICE
PARTS ORDERING
ii IM-LJS-13A

2 ape 4
7
1 — Gi iviveie
GULATED VOLTAGE OUTPUT
nl = 7
Seeieciiation
.
LOTOS
TONS.
OAT
ION
AIYO
§
0.4%
line
or
load
with
input
variations
from
105-132
_ or 132-105 volts AC and load variations from no
load to full load.
Rippleand
Noise.
. .
.....
.
.
.
.
10mV
RMS,
50mV
peak-to-peak
for
LJS-13A-5-OV,
-6-OV
models;
15mV
RMS,
100mV
peak-to-peak
for
LJS-13A-12-OV,
-15-OV,
-20-OV,
-24-OV,
and
-28-OV
with
either
positive
or
negative
terminal
grounded.
Temperature
Sccincient
=.
Change
in
output
voltage
0.03%/°C
max.
Remote Programming
External
Resistor.
.
. .
. . .
.
. .
.
Nominal
1000
ohms/volt
output.
Programming
Voltage
. . .
. . .
.
. .
One-to-one
voltage
change.
Remote
Sensing
.......
..
.
.
.
Provision
is
made
for
remote
sensing
to
eliminate
effect of power output lead resistance on DC
regulation.
IM-LJS-13A 1

STORAGE TIME — 16 ms min. at full rated current, maximum rated output voltage, and 105 VAC input.
OVERSHOOT — No overshoot under conditions of power turn-on, turn-off, or power failure.
INPUT
ACInput. .......... . . . 105-132 VAC at 47-440 Hz. Input power: 71
Watts*. For operation at frequencies above 440 Hz,
consult factory.
*With output loaded to full current rating.
DC Input. oes eas. ee AE VDC S107 input power) teen
+With output loaded to full current rating.
INPUT FUSE — Fuse F1 protects the input wiring to the power supply. Overload of power supply does
not cause fuse failure.
OVERLOAD PROTECTION
Electrical External . . . ... . . . . . Automatic electronic current limiting circuit, limits
output current to a preset safe value. Automatic
current limiting protects the load and power supply
when external overloads and direct shorts occur.
Internal ........ +... . .. . . Fuse F1 provides prevention against internal circuit
failure.
OVERVOLTAGE PROTECTION — All LJS-13A models include fixed built-in overvoltage protection
circuits which prevent damage to the load caused by excessive power supply output voltage. See table 7
below for overvoltage protector firing ranges.
OVERVOLTAGE PROTECTOR
TRIP-POINT RANGE
MODEL
(VOLTS)
INPUT AND OUTPUT CONNECTIONS — Terminal block on front of chassis. Reed-Prince no. 2 screw-
driver is required for terminal screws.
OPERATING AMBIENT TEMPERATURE RANGE AND DUTY CYCLE — Continuous duty from 0°C
to 71°C ambient with corresponding load current ratings for all modes of operation.
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IM-LJS-13A 3

OPERATING INSTRUCTIONS ‘ TORR
BASIC MODE OF OPERATION
This power supply operates as a constant voltage source provided the load current does not exceed the
rated value at 50°C. For continuous operation, load current must not exceed the rating for each ambient
temperature. When rated load current is exceeded, voltage decreases towards zero and the current at short
circuit is held to a safe value.
CONNECTIONS FOR OPERATION
NOTE: Make all connections to the unit before applying input power.
Ground Connections. The Lambda power supply can be operated either with negative or positive output
terminal grounded. Both positive and negative ground connections are shown in the diagrams for all
suggested output connections illustrated in this manual.
Connection Terminals. Make all connections to the supply at the terminal block on the front of the supply.
Use a Reed-Prince no. 2 screwdriver on terminal screws. Apply input power to input terminals; always
connect the ungrounded AC or DC lead to the bottom terminal.
The supply positive terminal is brought out to terminal +V. The supply negative terminal is brought
out to terminal -V. Recommended wiring of the power supply to the load and selection of wiring is shown
in figures 1 through 9. Selection of proper wiring is made on the basis of load requirements. Make all
performance checks and measurements of current or voltage at the front output terminals. Connect meas-
uring devices directly to terminals or use the shortest leads possible.
SUPPLY LOAD CONNECTIONS
Connections for Operation as a Constant Voltage Source
The output impedance and regulation of the power supply at the load may change when using the
supply as a constant voltage source and connecting leads of practical length are used. To minimize the
effect of the output leads on these characteristics, remote sensing is used. Recommended types of supply
load connections with local or remote sensing are described in the following paragraphs.
Refer to figure 1 to determine voltage drop for particular cable length, wire size and current
conditions. Lead lengths must be measured from supply terminals to load terminals as shown in figure 2.
Local Sensing Connection, Figure 3. Local sensing is the connection suitable for applications with
relatively constant load or for applications with short power output leads.
Remote Sensing Connection, Figure 4. Remote sensing provides complete compensation for the DC
voltage drops in the connecting cables. Sensing leads should be a twisted pair to minimize AC pick-up.
A 2.5 mf elect., capacitor may be required between output terminals and sense terminals to reduce noise
pick-up.
Programmed Voltage Connections, Using External Resistor, Figure 5. Discrete voltage steps can be pro-
grammed with a resistance voltage divider valued at a nominal 1000 ohms/volt change and a shorting-type
switch as shown in figure 5. When continuous voltage variations are required, use a variable resistor with
the same 1000 ohms/volt ratio in place of the resistive voltage divider and shorting-type switch. Use a low
temperature
coefficient
resistor
to
assure
most
stable
operation.
IM-LJS-13A

“3 o-oo a ae
Before programming, adjust programming resistor for zero resistance and set voltage adjust control to the
minimum rated output voltage. Output voltage of programmed supply will nominally be minimum output
voltage plus 1 volt per 1000 ohms.
As shown in figure 5, voltages can be programmed utilizing either local or remote sensing connections,
as desired.
Programmed Voltage Connections Using Programming Voltage, Figure 6. The power supply voltage output
can be programmed with an externally connected programming power supply. The output voltage change
of the programmed supply will maintain a one-to-one ratio with the voltage of the programming supply.
If the output voltage control of the programmed supply is set to minimum output voltage, output voltage
of the programmed supply will be minimum output voltage plus voltage of programming supply.
The programming supply must have a reverse current capability of 1.lma. minimum.
Alternatively, when supplies with less than 1.1ma. reverse current capability are used, a resistor
capable of drawing 1.1ma. at the minimum programming voltage must be connected across the output
terminals of the programming supply. This programming supply must be rated to handle all excess resistor
current at the maximum programming voltage.
Connections For Series Operation, Figure 7.
The voltage capability of LJS-13A power supplies can be extended by series operation. Figure 7 shows
the connections for either local or remote sensing in a series connection where the voltage control of each
unit functions independently to control the output.
A diode, having a current carrying capability equal to or greater than the maximum current rating of
the supply, must be used and connected as shown in figure 7. The diode blocking voltage should be at
least twice the maximum rated output voltage of the supply. See table I, of SPECIFICATIONS AND
FEATURES, for power supply current and voltage ratings.
OPERATION AFTER PROTECTIVE DEVICE SHUTDOWN
Fuse Shutdown. Fuse will blow when the maximum rated current value for the fuse is exceeded. Fatigue
failure of fuses can occur when mechanical vibrations from the installation combine with thermally induced
stresses to weaken the fuse metal. Many fuse failures are caused by a temporary condition and replacing
the blown fuse will make the fuse protected circuit operative.
Overvoltage Shutdown. When the power supply output voltage increases above the overvoltage limit, the
overvoltage protection circuit will short circuit output of the supply and shut down inverter operation.
After eliminating the cause(s) for overvoltage, resume operation of the supply by momentarily interrupting
the AC input circuit.
cn
IM-LJS-13A

MAINTENANCE
GENERAL
This section describes trouble analysis routine, calibration and test procedures that are useful for —
servicing the Lambda power supply. A trouble chart is provided as an aid for the troubleshooter. Refer
to the section on SPECIFICATIONS AND FEATURES for the minimum performance standards.
TROUBLE ANALYSIS
Whenever trouble occurs, systematically check all fuses, primary power lines, external circuit elements,
and external wiring for malfunction before troubleshooting the equipment. Failures and malfunctions often
can be traced to simple causes such as improper jumpers and supply-load connections or fuse failure due to
metal fatigue.
CHECKING TRANSISTORS AND CAPACITORS
Check transistors with an in-circuit transistor checker. If no checker is available, transistors can be
checked with an ohmmeter that has a highly limited current capability. Observe proper polarity for PNP
or NPN to avoid error in measurement. The forward transistor resistance is low but never ZERO; back-
ward resistance is always higher than the forward resistance.
Do not assume trouble is eliminated when only one part is replaced. This is especially true when one
transistor fails, causing other transistors to fail. Replacing only one transistor and turning power on, before
checking for additional faulty components could damage the replaced component.
When soldering semi-conductor devices, hold the lead being soldered with a pair of pliers or a commer-
cial heat sink device placed between the component and the solder joint.
NOTE: The leakage resistance obtained from a simple resistance check of a capacitor is not always
an indication of a faulty capacitor. In all cases the capacitors are shunted with resistances, some of
which have low values. Only a dead short is a true indication of a shorted capacitor.
PRINTED CIRCUIT BOARD MAINTENANCE TECHNIQUES
1. If foil is intact, but not covered with solder, it is a good contact. Do not attempt to cover with solder.
2. Voltage measurements can be made from either side of the board. Use a needle-point probe to penetrate
to the wiring whenever a protective coating is used on the wiring. A brass probe can be soldered to an
alligator clip adapted to measuring instrument.
3. Always use a heat sink when soldering transistors; a transistor pad with mounting feet is an effective
heat sink.
4. Broken or damaged printed wiring is usually the result of an imperfection, strain or careless soldering.
To repair small breaks, tin a short piece of hook-up wire to bridge the break, and holding the wire in
place, flow solder along the length of wire so that it becomes part of the circuitry.
3. When unsoldering components from the board never pry or force loose the part; unsolder the component
by using the wicking process described below:
a) Select a 3/16 inch tinned copper braid for use as a wick; if braid is not available, select AWG No. 14
or
No.
16
stranded
wire
with
1/2
inch
insulation
removed.
IM-LJS-13A

b) Dip the wick in liquid rosin flux.
c) Place the wick onto the soldered connection and apply soldering iron onto the wick.
d) When sufficient amount of solder flows onto the wick, freeing the component, simultaneously
remove iron and wick.
PERFORMANCE CHECKS
Check the ripple and regulation of the power supply using the test connection diagram shown in
figure 9. Use suggested test equipment or equivalent to obtain accurate results. Refer to SPECIFICATIONS
AND FEATURES for minimum performance standards.
Set the differential meter, DC DVM (John Fluke Model 891A or equivalent) to the selected power
supply operating voltage. Check the power supply load regulation accuracy while switching from the no
load to load condition. Long load leads should be a twisted pair to minimize AC pick-up.
Use a Variac to vary the line voltage from 105-132 or 132-105 volts AC and check the power supply
line regulation accuracy on the DVM differential meter.
Use a TVM, John Fluke Model 931B or equivalent, to measure rms ripple voltage of the power
supply DC output. Use oscilloscope to measure peak-to-peak ripple voltage of the power supply DC output.
ADJUSTMENT OF CALIBRATION CONTROL VR2.
Whenever voltage and current indications do not reflect maximum ratings, adjust VR2 as follows.
The adjustment procedure requires that the power supply is removed from associated equipment, is at an
ambient temperature of 25-30°C, and is stablized and not operating.
1. Remove AC input power to the supply.
2. Break seal on wiper of VR2 from resistor housing and turn to full CCW position.
3. Operate power supply for constant voltage with local sensing connected as shown in figure 3, with
no external load, and with AC input of 132 VAC, 60 Hz.
4. Turn voltage adjust control until minimum rated output voltage is obtained.
5. Apply load so that output current is 130-150% of 50°C rating for the unit.
6. Using a differential meter, DC DVM (John Fluke Model 891A or equivalent), observe output
voltage while adjusting VR2 in CW direction. Adjust VR2 until output voltage drops.
7. After adjustment is completed, remove AC input power to the supply and reseal wiper of VR2.
IM-LJS-13A 7

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2. Lambda part number. 3
3. Description of part together with circuit serene ne Te eter ana Lara?
u iret fete Se
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IM-LJS-13A

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LOAD
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LOAD
|
|
|
|
|
|
|
|
|
|
|
| VAC
| OR
LE: a [Sig tig
/ NECT JUMPER FROM % FOR NEGATIVE GROUND DISCONNECT JUMPER FROM
: SEEHINALE EV AND-d AND RECONNECT TO-VAND + TERMINALS +V AND € AND RECONNECT TO-VAND +
% % A 2.5MF,ELECT, CAP. MAY BE REQUIRED,
Figure 3. Local Sensing Connections. Figure 4. Remote Sensing Connections.

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(A) LOCAL SENSING
Figure 5. Programmed Voltage, With External Res istor.
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PROGRAMMING Mappa esl
VOL TAGE : VOL TAGE
LOAD
% FOR NEGATIVE GROUND DISCONNECT JUMPER FROM
TERMINALS +V AND *# RECONNECT TO-VAND ¥.
% % A2.5MF,ELECT.,CAP.MAY BE REQUIRED.
(A) LOCAL SENSING (B) REMOTE SENSING
Figure 6. Programmed Voltage, With External Programming Voltage Source.

SODA. bate 32>
a De
(A) LOCAL SENSING (B) REMOTE SENSING
% MAKE ONLY ONE GROUND CONNECTION FOR SERIES COMBINATION. TO Agta 1
GROUND AS SHOWN, REMOVE JUMPER FROM TERMINALS +V AND * O
UNIT AND CONNECT ANY ONE OF THE OTHER JUMPERS AS SHOWN NY
DOTTED LINE.
% % A2.5MF,ELECT.,CAP. MAY BE REQUIRED.
Figure 7. Series Connection.

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Pasi a
Typical
Block ee Pe
| ae Be a i
ite | > = a
Figure 8.
e* res
OSCILLOSCOPE
= RIPPLE
METER
DIFFERENTIAL |
METER
(VTVM)
|
|
|
|
ft
| -s
>]
a|
ef NC
3
a | NC
Input
| | 105-132
VAC
||
47-440Hz
115
VAC
OR
| |!30-160
VOC
|
| te LINE GND
Ll ee NOTES
|. REGULATION AND RIPPLE CHECK METERS MUST NOT BE GROUNDED
THROUGH THREE WIRE LINE CORD TO GROUND.
2. PERFORM CHECKS WITH LOCAL SENSING CONNECTIONS ONLY.
Figure
9.
Test
Connections
for
Performance
Checks.

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