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I
SOLIDSTATE,
HIGH.VOLTAGE,
REGULATED
DC POWER
SUPPLY
i
trIYNASCAN
COF|POF|ATION
CONTENTS
PAGE
SPECIFICATIONS 3
FEATI.JRES 3
INTRODUCTION 4
OPERATINGCONTROLS 4
OPERATINGINSTRUCTIONS 5
APPLICATIONS .....7
DESCRIPTION
CIRCI.JIT . . .I1
MAINTENANCE .....13
CALIBRATION . l3
FUSEREPLACEMENT . .. .14
WARRANTY Cov- 3
SPECIFICATIONS FEATURES
INPUT VOLTAGE 105- I25VAC,60 Hz
Fully solid state,utilizingintegrated circuits, silicontransis-
4OOV SUPPLY
DC tors and diodesand one SCR.Among the advantages of
solidstateconstruction dependability, warm-uftime
are no
Output Voltage: 0 - 400V, continuously vari- or stabilizationdelay,ruggedness, compact size.
able. Current Umiting/OverloadProtection: Protectsload and
OutputCurrent: 0 - 20OmA. instrument againstoverload. Pre-settable automatic current
GrrrentLimit Adjust- lOmA to 200rnA, continu- shutdown, fully adjlstablefrom l0rnA to 200mAprovided
ment/Protection: ously variable-sets
trip cur- on.theB+ output. Resistive limiting protectsthe C- supply
rent to shut-down
supplyout- andload.The6.3VACandthe 12.6{IAC heater windingdinb
put. loads protected a resettable
are by circuitbreaker.
LoadRegulation: 0.1% highend.
at Simplified Cunent ShutdownSetting: PermitssettingB+
Line Regulation: 0.t%. current shutdownpoint without disturbing external load
Noise& Ripple: Less than lOmVpeak-to-peak. connections output voltagesettings;
or does not require
applicationof short circuit to output terminals.sirirply
press button and adjustthe CURRENT
the SETcontroitb
IOOV SUPPLY
DC the desiredsetting the currentmeter.
on
OutputVoltage: 0 - 100V, continuously
vari- O400V,G200mA: Outputvoltage continuously adjustable
able. over.entire -rgngewjth g single control;no rangeswitching
OutputCurrent: 0 - 2mA. required. Fully regulated output at all levels.
LoadRegulation: r% G100V, G2mA: Output voltagecontinuouslyadjustable
Line Regulation: lVo gver.entire rang with a singlecontrol; indepehdently
Noise Ripple:
& Lessthan 1OmVpeak-to-peak. tloatingoutput. Canbe usedindependently the 0400V
of
Protection: oglpgt or canbe usedwith eitherpolarityreferenced the to
Current-limiting resistance. 400V output.
6.3VAC,I2.6VAC CT, G3.5A: Independently
floatingAC
6.3VAC(Non-Adjustable) sources.
OutputVoltage: 6.3V !57o,full load; I IOVAC Dual Meters: Allow B+ supply output voltage and B+
primary. supplycurrent drain to be monitoredsimultanebusly. The
OutputCurrent: 3.5A continuous. voltmetercan alsobe switched monitor the biasiupply
to
Protection: voltage. Both metershaveoverload protectionto prevent
Thermal circuit-breaker.
damage from excessiveloading.
12.6V (Non-Adj
AC ustable) one current Range: Simplifies current shutdownsetting
by requiring only oneadjuitment.
Center-Tap
Supply Two Voltmeter Ranges:0-400Vand Gl00V ranges the for
OutputVoltage: 6.3V!5%,fuIIload;I I0VAC B+ and C: suppliesrespectively provide maximu=m resolu-
primary,each sideto tion with a minimumeffort to the user.
center-tap. Standby-DCOn Switch:Disconncts DC supplies
the from
OutputCurrent: 3.5Acontinuous. externalloads without disturbingvoltageor iurrent set-
Protection: Thermalcircuit-breaker. tings.
Pilot- Lamp: Lights up to indicate at a glance that the
METERING supplyis on.
Voltmeter Ranges):
(2 Mechanicalhe-Regulator: B+ supply rectifier voltage is
0 to 400V DC (400V supply increased progressive
in stepsas output is increasea.
inis
only), !37o. improves efficiencyas lesspower is converted heat at
to
0 to l00V DC (100Vsupply low voltage output.
only), !3%. Floating outputs: Permit referencing positiveor nega-
the
Range selected switch.
by tive outp_uls the-B+ supply and the C- supply to any
of
Milliammeter: 0 to 200mA(monitors 400V external potentialor grounds.
DC
supplyonly), t3%. Reverse ?olarity hotection: Preventsagainst accidental
DIMENSIONS(Overall); 14-118" 3-7 8" x 10" deep.
x f damagefrom reverse polarity connections an external
to
powersource.
NET WEIGHT: I I lbs.
Attractive, Functional tlesign: Permits stackingof units
-
whenmorethanonepowersupplyis required.
E"ry t9. Ope_rate: controlsare identifiedand easyto
All
rgad- Simplifiedoperation - prevent
helps operator mistakes
that might damage equipment.
INTRODUCTION
The B & K Precision Model 1602 High Voltage Power Following is a list of some of the most popular applications
Supply is a versatile,laboratory quality instrument which of 1602:
pr6vities regulated DC voltages and currents of 0-400V at o Service Technicians: Powering high voltage solid state
bZOOmn and G100V at G2mA; and AC voltages and equipment, or individual circuits consisting of transis-
currents of 6.3 and I2.6VAC at 0-3.5A. The high perfor- tors, vacuum tubes or both.
mance, operating ease, and special features make it an
^choice-
excellent for most applications requiring a high o Factory Technicians: Powering complete equipment
voltage DC power source. It is well'suited for,powering or individual assembliesduring testing in the factory.
-solid
fully siate circuits, tube type circuits,.and hybrids. o Engineers and l:boratory Technicians: Powering pro'
Unlike some supplies,the user can rectify the AC.source totypes and experimentalequipment.
and have 3 indefendent suppliesfor powering digital/analog
circuits, etc. o Electronics Instructors and Students: Laboratgry ex-
periments in basic and advancedelectronics.
OPERATING CONTROLS
6 8
og
@
B@e @
14 12 11
Fig. 1. Controls and Indicators.
l . CURRENT METER. Measuresactual B+ output load 6. POWER.Ughts continuouslywhen power supply is
current during normal.operation. Indicates Bt current turnedon.
limit when set/resetswitch 3 is pustred. groundterminal-
7. TERMINAL. Earth andchassis
2. B+ CURRENT SET. Provides adjustment of B* cur- B+ TERMINALS
rent limit. Continuously adjustable from l0-200mA
output current. 8. + TERMINAL. Positivepolarity of B+ output.
PUSHTO SET AND RESET(SET/
3. B+ CURRENT 9. - TERMINAL. Negativepolarity of B+ output.
RESET)BUTTON: Whenfully depressed held,
and 10. VOLTMETER.Indicatesoutput voltageof B+ or C-
cunent
connects 1 the
meter fo read B+ currentlimit srpplies.
setting.Whenpressed released,
and resets overload
B+
circuitif it hasbeentripped. ll. METERRANGE. B+/G400position:Selects scale full
ranseof 400voltsfor voltmeter10 to meter$+ output
4. OVERLOAD INDICATOR (RED). Lights when B+ vollage.C-/G100position: Selects full scalerangeof
currentlimit hasbeenexceeded the B+ zupplyhas
and 100f for voltmetei10 to meterC- outputvoltage.
strutdown.
5. STBY ON. STBY position: Removespower from 12. LEVEL (B+). Turns off power supply at extreme
terminals 9, 13, and14, and voltmeter
8, 10, but rotation.Clockwise
counterclockwise rotation turnson
leaves the DC supplies activated and at standby power supply and adjustsB+ output voltageupwards.
condition. ON posifion: Applies power to oirtput
terminals 9, 13, 14, andvoltmeter10.
8,
C-TERMINAI,s 16.& 18. 12.6VAC TERMINALS. l2.6VAC output ter-
13. - TERMINAL. Negative polarity odtput of C- supply. minals.Protectedby breaker 19
14. + TERMINAL. Positive polarity output of C_supply. 19. AC RESET. Circuit breakerin series with terminal16
protectsagainst excessive
overloads
betweenterminals
15. C- CONTROL. {,{gsts C- output voltagebetween 1 6 , 1 7a n d 1 6 , 1 8 .
terminals and 't4 from 0 to-100Vwitf, clockwise
13
rotation. Output voltage is monitored on Volt- NOTE: At17 and18 6.3VAC is available. This output is
meter 10 when METER RANGE Switch 1l is in protected by an internal fuse. For maximum
C-lGl00Vposition. convenience and minimum down-time due to
accidentalshort-circuitsuse the breaker-protected
16.& 17. 6.3VACTERMINAIS. 6.3VAC output rer-
A C outputs16 , 17 and 16, 18.
minals.Protected breaker19
by
OPERATING INSTRUCTTONS
l. Turn off the power supply before pluggingit into an (b) Push the SET/RESET3 button in and adjust
AC outlet, by rotating the LEVEL control 12 fully the B+ CURRENT SET 2to at least50mA on
counterclockwise,until it "clicks" off. CURRENT METER 1 if not already,and reset
2. Connectthe power cord to a 105-125volt 60 Hz AC to the desiredcurrentlimit.
outlet. (c) Release SET/RESET3 button and return
the
WARNING STBY/ON 5to ON postiition..
a. Use only a polarized3-wire outlet. This assures
If an overload in the circuitry being powered
that the power supply chassis connected a
is to exists,the supply will shutdown as normal.
good.earth.ground and preventsdangerfrom
electrical shock. lf a 2-wire to 3-wire- adapter At very low output currents, decreasing the B+
m_ust used, be sure the ground wire of the
be output voltage between l50V to 400V may
adapteris attachedto a good earth ground. activate the QI-VCE sensingcircuit before the
desiredB+ output is reached VOLTMETER 10.
on
b. If a circuit under test requiresapplicationof a
The supply will shutdown and the OVERLOAD
fixed bias, always apply the required voltage
lamp 19 will light. To reset, simply proceed as
usingthe_C- supp-lyfirst; before applying the Ii'+ statedin (a), (b), and (c) above.
voltage(Step 6-d).
Turn gn-lhr_ qower supply by rotating the LEVEL 5. Connect the. powe_rsupply output to the devicebeing
control 1Z slightly clockwise past the-.,click". The poweredwith test leadsas follows:
-
POWERindicator 6 will light. a. connect th9 positivepolarity high voltageinput of
4. Determine the maximum safe load current for the the device being powered to the (+) teririnaf 8 of
device to be powered and set the automatic current the B+ supply.
strutdownfor that valueas follows: b. Connectthe negative polarity high voltageinput of
a. Pushand hold the set/reset bu_tton3 and adjustthe the device being powered to the (-) terminaf g of
B+ CURRENT SET control 2 for the desiredshut_ the B+ supply.
down current point as read on the CURRENT c. If the positivepolarity of the devicebeingpowered
meter 1 . is to be^the ground reference,j_lrmpeithe . (+)
-
b. Release set/reset
the button 3 . terminal 8 to the ground terminal 7 .
- If the negativepolarity of the devicebeingpowered
c. Turn LEVEL (B+) control 12 to the desired is to be^the ground reference,conneJt^ the o
voltage. terminal 9 to the ground terminalT.
d. If the maximum safeload current is unknown. start If neither the positiveor the negativepolarity input
with a low current setting.If the settingis too low, of the devicebeing poweredneedsto be grouniled
the overloadcircuit will trip when pow6r is apphed but the chassis of the device needs grounding,
t o t he loa d i n s te p s6 a n d 7 .l fi o , i n creai r' tf,. connect a separate test lead from the chassis the
of
current_setting in small steps until the overload device to the ground terminal 7 of the B+ supply.
circuit doesnot trip during normal operation.
d. Follow the.above proceduresfor the C_ supply,
u.silg^plus (+) terminal 14 and minus (-) teiririir_
NOTE 13.
In certain conditions of high-line voltagesor B+
NOTE
OUTPUT. voltages gre,ater ihan 100V,-resetting Ih.r C- -supply and the B+ supply are entirely
independentof eachother. Whena iircuit requires
rygy.not be accomplishedby simply pushing thJ
SET/RESET buttbn.(ThisisOue the qr-"VCE
3 t6 a.biasvoltagewhich is negative with respectto the
sensing
circuitry described
underCURRENT-VCE circuit reference,the (+) terminal 14- of the C-
SENSING CIRCUITS, page13.)Should occur supply is connectedto this reference.Refer to Fie.
this
proceed follows:
as 2.
(a) Set the STBY/ONS switch to the STBY e. C onnect the A C vol tage source s ( t er m in_
position. als 16 , 17 andlor 1G , 18lto the device if ;;_
quired.
srG T N
H
H6Bm"
Flg. 2. Typical Vacuum Tube Circuit Application.
6. Return the STBY-ONSwitch 5 to the ON position (3) lncrease the strutdown point slightly with the
andsetthe outputvoltage follows:
as B+ CURRENT SET control 2 .lt the normal
load current is unknown, this techniquemay be
a. Set METER RANGE Switch to C-l0-100V when used, but, if the current limit is already set for
adjusting supplyoutput.
C- the maximum safeload current, do not increase
voltage reached.
b. Turn C- control 15 until desired is the current limit further.
c. Set the METER RANGE switch 11 to B+/G400V (4) Check the bias setting to determine if it is
when adjustingB+ supply output . incorrectly set.
d. Turn LEVEL control 12 clockwise until voltage is (5) Refer to NOTE under 4d, Page5.
reached.
NOTE NOTE
When a fixed bias is required for a circuit under Some equipment has a highly capacitive input,
test, always perform Steps a and b first. (C- bias which results in a surge current when power is
level.) initially applied. When powering such equipment,
the overl,oad circuit may activiate when the
7. If the B+ load current exceedsthe current shutdown STBY-ON switch is placedin the ON position with
point, the overload lamp 4 will light, and the B+ full operatingvoltagepreviouslyset. If this occurs,
supply will shut down (cunent meter 1 and volt- reduce the voltage setting before resetting the
meter 10 will drop to zero). Restorethe power supply overload and then bring the output level up
to normal operation as follows: gadually to allow the capacitorsin the equipment
to charge;this eliminatesthe surgecurrent.
a. To reset the power supply, press and releasethe
set/reset button 3 . If the overload was intermit-
tent, this will restorenormal operation. c. If the power supply continues to shut dodn at the
correct current setting, check the load circuits to
b. If the overload lamp remains lit, use one of the determinethe reasonfor the overload.
following techniques before resetting the power
supply again. d. To remove power from the load without disturbing
the voltage or current shutdown settings, set the
(l) Reducethe load current. STBY-ON switch 5 to the STBY position.
(2) Reduce the voltage slightly with the LEVEL
control 12 . e. Refer to NOTE under 4-d, page5.
APPLICATIONS
General 4. Connect the B+ lead to the (+) terminal I of the B+
This instrument may be used to power a vast assortmentof supply to provide power for the plate and screengrid
circuits and devices in the fields of electronics servicing, of the tube.
electronics manufacturing, electronics design engineering, 5. Connect the common lead to the (-) terminal 9 of the
and electronics education. The l+ and C- supply outputs B+ supply. This point is alsonormally connectedto the
are fully adjustable over their full range, while the low ground t6rminal- 7 , for strock hazatd prevention. The
voltage AC iource remains fixed. This flexibility makes it ionnection between ground and the (-) terminal 9 of
suitable for most applicationsrequiring a singleor multiple the B+ supply may not be used during some types of
output high voltage supply. -
experimentJ, such as positive grounds and floating
Powering Tube Type Circuits supply inputs.
Fig.2 shows the 1602 being used to supply the operating With the meter switch in the C-/G100V position, adjust the
voltages a typical vacuum.tubeRF amplifier stage.
in C- control for the desiredbias level.
l. Connect the filament of the tube to terminals 16 and Before the S+ output voltage is adjusted, press the B+
17 for 6.3VAC heater operation or to 16 and 18 if current set/resetbutton and adjust the B+ CURRENT SET
l2.6VAC heatervoltageis required. control for the maximum output current desired.Now the
S+ voltage level may be increasedto the required level-If
2. Connect the grid resistor to the (-) terminal 13 of the the current overload circuit shuts down the B+ output,
C-supply. either increasethe B+ current set, or decreasethe output
3. Connect the (+) terminal 14 of the C- supply to the current drain by increasing the C- output voltage. (Also
(-) terminal 9 of the B+ supply. refer to NOTE under 4'D, Page5.)
\
t-)
I
SIG OUT
G I N
=
H
V cc
g6:gB6Em"
Fig. 3. Typical Triinsistor Circuit Application.
Powering Transistor Type Circuits
Fig. 3 showsthe 1602 Power Supply being used to power a In some circuits the chassis connectedto the positive Vcc
is
transistofamplifier circuit. line which meansthe ground terminal should be connected
to the (+) terminal 8 of the B+ supply. Fig. 4 shows the
l. Connect the Vcc lead of the circuit to the (+) various methods to connect the 1602 to accommodate
terminal 8 of the B+ supply. different equipment power/ground configurations.If there
2. Connect the common lead of the circuit to the (-) is any doubt which supply lead is common to the chassis,
terminal 9 of the B+ supply and to the ground no damage lead is connectedfrom the
will result if a separate
terminal 7. chassis the ground terminal 7 .
to
EQUIP},IENT EQUIPI\4ENT
BEING BEING
POWERED POWERED
Fig.4. Power Supply Output Situation.
Other Educational Uses
The student in an electronics course may use the power Although two supplies may be used safely in the above
supply for powering equipment and circuits as previously situations, it is not recommended that the supplies be
describedfor all other applications.In addition, the power operated in seriesfor voltageshigher than 400V. Also, to
supply can be used to conduct experimentsin fundamental avoid shock hazards,do not connect both ground terminals
electronics.In learningOhms law, for example,the relation- to the power supply output terminals; doing so may place
strips of resistance,voltage and current are easily demon- the entire power supply chassis a high potential.
at
strated with the supply. Being able to observeboth voltage
and current simultaneously is a geat aid in such experi-
ments. Fig. 5 shows some examples of the types of
experimentsthat may be conducted.
Using Two Supplies for Two B+ Voltages
Whrn two separateB+ voltagesare required simultaneously
for testing equipment, two supplies may be used. Set the
voltage and current limit for each supply independently as
required by each load requirement. Only the circuit
referencepoint must be common betweenthe two supplies.
Fig. 6 showssometypical examplesof proper power supply
connections when using two units. Take extra precautions
to prevent reversepolarity connectionsin such situations.
The numerous connections can become confusing. Ad-
ditional colors for the test leadswill be helpful. The'power
suppliesare protected from reversepolarity damagefrom
an external voltage source such as the other power supply.
8
OBSERVE
CHARACTERTSTIC OF DIODE
@ o o cEl MEASURE
Vnt &
E@= E@e VARY ETN
I
I MEASURE Vot
VARY Etrv
& I
CHARACTERISTIC OF ZENER DIODE
II{EASURE VVnt &
VARY Eru
OBSERVE
OHMS IJAII
E
^-T
BASIC CURRENT DIVTDER
rnr
^ -a>
12-
tr* *-.
#fu, r1
tr*
r1= sfu; -
=
11+12 tT*
Fig. 5. Typical Laboratory ClassroomExperiments Using the 1602 Power Supply.
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CIRCUIT DESCRIPTION
C'eneral
The power supply convertsa llTVAC input to a highly The C- and CONTROL unregulated DC sourcesare fairly
regulated and filtered DC output that is fully adjustable standardand straightforward.
from 0 to 400 volts at G200mA at the B+ terminals; and
Secondary winding No. 2 provides power for the com-
G100V at 0-2mA at the C- terminals. The supply also parator ICI and voltagereference and error amplifier IC2.
convertsits AC input to a l2.6VAC center-tapped output This supply is designedto be free of influence from the
at G3.5A. The circuits that accomplishthis action may be
unregulated B+ supply. The 20 volt AC output from
divided into 4 main groupsas follows:
secondary winding No. 2 is convertedto +15V and -15V by
l. UnregulatedDC and AC sources:Converts the AC full wave,rectifiersDl and 2. Both the V+ and V- voltages
input to raw DC for the B+ and C- control and filter float with respectto the regulatedoutput and the unregu-
circuits; and stepsdown the AC input for the l2.6VAC lated B+ supply variations.
filament windings.
Secondarywinding No. 3, diode D9 and Cll provide half
2. Control circuits: Control the unregulated B+ and C- wavefiltered DC for the C- control and filter circuits.
sources to provide the highly regulated, adjustable
outputs. B+ and C- Control Circuits
3. Current sensing The B+ control circuit converts the unregulatedB+ supply
circuits: Establishthe B+ current limit,
sensethe B+ load current, and activate an overload into the regulated l+ output voltage. The control circuit
establistres the regulated B+ output voltage in responseto
detector that shuts down the B+ supply if the current
limit is exceeded. the setting of the LEVEL control R22. When R22 is set for
0 volts, the following circuit conditions exist:
4. Metering: Monitors the B+ or C- voltage, and the B+
output current. Refer to Fig. 7,the functional diagam l. Voltage referencelCzA providesa stable+7V reference
atlC2-6.
and to the schematic diagram. Circuit descriptions
make constant referenceto thesediagrams. ") The +7V referenceis divided acrossRlO and Rl l to
place +3.5V at pin 4,IC2, the invertinginput of error
NOTE: The voltagesin the following circuit descriptions
amplifier IC2B.
and on the diagrams are measuredwith respect to the
regulatedB+ output, the + terminal, or the C- output, and 3. The regulatedB- voltageis 0V.
- terminal. Note that these points are floating indepen-
dently of the chassis the power supply.
4. The +7V reference is divided across current Path I,
of
which consistsof R23, Rl2, R30, and R2l (R22 is
Unregulated DC and AC Sources approximately 0 ohms at this time). This places
approximately +3.5V on IC2-5, the non-invertinginput
There are three unregulatedDC sourcesand one unregu-
of error amplifier lC2-13.
lated AC source in the supply. The most important
unregulated supply is the B* source.This source converts 5 . Error amplifier lC2B will produce whatever output is
I ITVAC to a raw unregulatedB+ output. Later, the control necessaryto keep the difference voltage at its inputs,
and filter circuits convert this to the regulatedB+ output of pins 4 and 5, very close together.Therefore,with R22
the power supply. at about zero ohms, just enough drive will be applied
to seriespassregulatorQl, Q2 to maintain a zero volt
The unregulated B+ output level is pre-regulatedin coarse
B- output.
steps.As the LEVEL control is rotated clockwisefrom zero
to maximum,the unregulatedB+ changes from its lowest to 6. The seriespass transistors are being slightly driven at
its highestvaluein four steps.This minimizes the difference 0V output to avoid non-linearities at low output
between the unregulated B+ and the regulatedB+ output, (iumps in output, poor regulation,etc.).
voltages
which alwayskeepspower dissipationwithin safelimits.
The main components which make up this circuit are
winding No. 1 of power transformer Tl, pre-regulator When LEVEL control is increasedto a higher voltage level
switch assembly 52, rectifiers D5, 6, 7, 8, and filter the following circuit action occurs:
capacitorC8. 1. The resistanceof R22 is added to the voltage divider
The AC input is applied to the unregulated B+ circuit current I1.
network, decreasing
through on-off switch 54 (which is part of the level 2. The voltage at lC2-5 increases(less drop acrossR23,
control) acrossneon lamp NEI (which glows continuously l2), and error amplifier IC2B increases output to
its
as a pilot lamp to show that power is on) to power drive seriespasstransistor Q l, Q2 into heavierconduc-
transformer T1. tion.
3. The regulator allows some of the B+ supply to passto
TransformerTl has four taps in its output winding No. l. the output, and the output voltagerises.
At the lowest voltage setting, only the low voltageportion
4. As the output voltagerisesthe B- supply becomesmore
of the winding is connected to the rectifiers (this is the
negativewith respectto the B+ terminal.
condition shown on the schematicdiagram).As the LEVEL
control is rotated clockwise,cams operatemicroswitches 5. Current I increases the B- becomesmore negative,
as
S2C, then S2B, and finally S2A. Each cam-operated until balance is
and the voltage at IC2-5 decreases
microswitch selectsanother tap on this secondary of the achieved.
transformer and sequentially steps the rectifier input
When LEVEL control R22 is decreased, oppositeaction
the
voltageto a higher value.
occurs. Once R22 is set and balanceis achieved,any load
Rectifier diodesD5, 6, 7, and 8 convert the AC to full wave current changesthat tend to changethe output voltageare
DC, which is filtered by C8. The unregulated!+ output at sensedand corrected.
C8 is regulatedand filtered by the control circuits.
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The C- control circuit converts the unregulatedC- supply switch SCR-I and turns it on. SCR-I groundspin l0 of
into the regulated C- output voltage. This control estab- error amplifier IC2B, which inhibits its operation regardless
listres the output level in responseto the setting of the of all other inputs, shutting down the power supply. SCR-l
BIAS control, R35. also provides the ground path which allows the overload
The voltage referencefor this circuit consistsof D2l ,C14, lamp to light. Set/reset switch 53 shorts across SCR-I,
and R34. Referencediode D21 acts as a constant voltage when it is depressed, replacethe current path.
to
sourcefor R35. The wiper of R35 is connectedto the base
of Q3, so the output voltage will always be .6V less than NOTE
the control setting. Any variations in the unregulated C-
Besidesthe current-sensing function, another cir-
voltage are absorbed across R34, becauseas the voltage
cuit comprisedof R40, D25,D24, and Rl7 senses
acrossD21 increasesabove its referencevoltage, its inter-
the collector-emitter voltage of Ql above 200V.
nal resistance
drops to draw more current.
During overloads and some reset conditions the
fu 12 increases, voltage drop acrossR34 also risessuch
the
value of the collector-emitter voltage and the
that the reference voltage stays constant. Diode D2l is
collector-current of Ql can shift the operating
biased so that its voltage never drops below its reference point of Ql out of its S.O.A. (Safe Operating
point.
fuea) curve. The avalanchebreakdown of D25 and
If the load on the output increases, output voltagewill
the D24 is such that for collector-emitter voltages
attempt to drop. This will turn Q3 on harder, increasingthe geater than 200V, a voltage is developedacross
output current, which restoresthe output voltage. R17 that adds to the voltage developedby the
output current acrossRl. This summedvoltageon
The oppositeeffect occursas the output load decreases. pin 2 of ICl represents an equivalent power
Overloaddescription: Resistance-limited. dissipation value that is under the S.O.A. curve of
Q1. Therefore, when this summedvoltage reaches
Current-VCE SensingCircuits the preset voltage on pin 3 of ICl, a strutdownof
output voltageand current occurs.
The main components in the current sensing circuits are
comparator ICl, overload switch SCR-1, and current sense Metering
resistor Rl. This circuit monitors the B+ load current and Voltmeter Ml is connected directly acrossthe output of
sttuts down the B+ supply if the load current is exceeded. the B+ supply or the C- supply, to measureoutput voltages.
The current sensingresistor, Rl, is selectedso that IV is Meter Range switch M selects the proper input and the
developed across it when exactly 200mA load current is proper series resistor to calibrate the meter for either
drarvn. The voltage across this resistor is applied to the G400V full scale,or G100V full scale.
non-invertinginput of the comparator,ph 2,lcl.
Current meter M2 is actually a voltmeter calibratedto read
The inverting input, ph 3, is connectedto a variable 0-1V S+ output current. The meter measures the voltage devel-
voltagesource,R5, the Bf current limit control. oped acrossthe current sensingresistor,which is exactly I
volt for a full scalemeter reading.When setting the current
Wheneverthe output load current producesa voltageacross limit, switch 53 is actuated, which connects the current
Rl that is greater than the preset voltage on the inverting meter directly acrossthe B+ current set control R5. This
input of the comparator, ICl, a positive lV signal appears control selectsa voltage from GlV, which very accurately
at output pin 7. This output drives the gate of overload corresponds the current limit value read on the meter.
to
MAINTENANCEAND CALIBRATION
The following instructions are for use by qualified personnel only. To avoid electrical shock, do not perform
servicingother than contained in the operating instructions unlessyou are qualified to do so.
High voltage up to 500 volts is present when the power supply is operating. Line voltage (120 VAC) is
present on the fuseholder and on-off switch any time the. power supply is connected to an ac outlet, even if
turned off. Always observecaution when the top cover is removed. Contacting exposed high voltage could
result in fatal electrical shock.
MAINTENA}ICE pre-regulator supply to 500V to theboard.
can up DC
This power supply is built to provide long, trouble-free CALIBRATION
serviceand does not require periodic maintenance.If the Use insulated adjusting tool, and exercise CAUTION- the
unit malfunctions, use conventional troubleshootieg tech- P.C.B.has over 400V DC potential at maximum settings.
niques, such as voltage and resistor checks to isolate the
defective component. If defectivecomponentsare replaced To gain accessto the calibration adjustments, remove the 3
the unit should be recalibrated. note on safety: Whenever
A screwsat the rear of the top cover, then lift the top cover at
servicing this unit keep the level control R22 below one the rear and slide the front lip of the cover from the
third rotation (no microswitches activated) to keep the retaining bosseson the front panel. Refer to Fig. 8 for
maximum DC voltage below l60V DC. Rememberthat the locations of calibration adjustments.
l3
l00v METERCAL (R26)
l. Connect an accurate,calibratedvoltmeter to the
output terminals and 14 , capable l00V read-
13 of
ing-
2. Set the METER RANGE switch 11 of the power
supply to the C-lG100 position.
3. Adjust the C- control 15 for exactly 100V on the
externalvoltmeter.
4. Adjust l00V CAL potentiometer (R26) for exactly
l00V on thevoltmeter the 1602
of powersupply.
MAX. OUTPUTADJ. (R23)'
1 . Connect an accurate,calibratedvoltmeter to the
outputterminalsSand 9, capable 400V reading.
of
fl,'
Set the LEVEL control 12 of the 1602powersupply
to MAXIMUM.
3 . Adjustthe MAX. OUTPUTADJ.potentiometer (R23) 100v
METER
for exactly402Volts on the external
voltmeter. CAL LIMIT
I CAL
CURRENT 400v
METER
CAL
400v METERCAL (R3l)
MAX
l. Connect an accurate,calibratedvoltmeter to the OUTPUT
ADJ
output terminals8 and 9 , capable 400V reading.
of l
Fig. 8. Location of Calibration Adjustments
2. Set the METER RANGE switch 11 to the 0-400
and Fuses.
positlon.
3. Setthe LEVEL control 12 of the 16O2 powersupply
to readexactly400 Volts on the external
voltmeter.
4. Adjust 400V CAL potentiometer (R3l) for exactly
400 Volts on the voltmeterof the 1602powersupply. NOTE
If the unit has just been serviced,
reconnect the
load used in Step 2, to check the current limit.
Adjust LEVEL 12 for 50mA on the current
CURRENT METERCAL (R27) MCtEr.ROtAtEB+ CURRENT SET C.C.W. UNtiI
"OVERLOAD"
l. Refucethe 1602LEVELcontrol 12 to minimum. LIGHTS. Press button 3 to
check accuracy. If OVERLOAD DOES NOT
2. Connectan accurate, calibratedammetercapable of LIGHT, CURRENT LIMIT CIRCUIT IS BAD.
200mA in serieswith an appropriateload (250 ohms, Also refer to NOTE under 4d, page 5.
l0 watts) to the output terminals and 9 of the
8
1602 powersupply.
3. Adjpst the LEVEL control"12 for exactly200mAon
the externalammeter. FUSE REPLACEMENT
4. AdjustCURRENT METERCAL. potentiometer (R27) If there is no power supply output, and the POWER lamp
for exactly 2OOrnA the currentmeterof the 1602
on does not light, check fuse Fl. If the POWER lamp lights,
powersupply. but there is no output from the main 400V supply, check
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