1602 DC Power Supply Instruction Manual

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
DESCRIPTION
CIRCI.JIT
MAINTENANCE
CALIBRATION .
FUSEREPLACEMENT
WARRANTY
.....7
. . .I1
.....13
l3
. .. .14
Cov- 3
SPECIFICATIONS
INPUT VOLTAGE
105- I25VAC,60 Hz
4OOVDC SUPPLY
Output Voltage:
OutputCurrent:
GrrrentLimit Adjustment/Protection:
LoadRegulation:
Line Regulation:
Noise& Ripple:
0 - 400V, continuouslyvariable.
0 - 20OmA.
lOmA to 200rnA, continuously variable-setstrip current to shut-downsupplyoutput.
0.1%at highend.
0.t%.
Lessthan lOmVpeak-to-peak.
IOOVDC SUPPLY
OutputVoltage:
OutputCurrent:
LoadRegulation:
Line Regulation:
Noise& Ripple:
Protection:
0 - 100V, continuouslyvariable.
0 - 2mA.
r%
lVo
Lessthan 1OmVpeak-to-peak.
Current-limiting resistance.
OutputCurrent:
Protection:
6.3V !57o,full load; I IOVAC
primary.
3.5A continuous.
Thermal circuit-breaker.
12.6VAC (Non-Adjustable)
Center-Tap
Supply
OutputVoltage:
OutputCurrent:
Protection:
6.3V!5%,fuIIload;I I0VAC
primary,eachsideto
center-tap.
3.5Acontinuous.
Thermalcircuit-breaker.
METERING
Voltmeter(2 Ranges):
DIMENSIONS(Overall);
0 to 400V DC (400V supply
only), !37o.
0 to l00V DC (100Vsupply
only), !3%.
Rangeselected
by switch.
0 to 200mA(monitors400V
supplyonly), t3%.
14-118"
x 3-7f 8" x 10" deep.
NET WEIGHT:
I I lbs.
Milliammeter:
Fully solid state,utilizingintegratedcircuits,silicontransistors and diodesand one SCR.Among the advantages
of
solidstateconstructionaredependability,
no warm-uftime
or stabilizationdelay,ruggedness,
compactsize.
Current Umiting/OverloadProtection: Protectsload and
instrumentagainstoverload.Pre-settable
automaticcurrent
shutdown,fully adjlstablefrom l0rnA to 200mAprovided
on.theB+ output. Resistivelimiting protectsthe C- supply
andload.The6.3VACandthe 12.6{IACheaterwindingdinb
loadsareprotectedby a resettable
circuitbreaker.
Simplified Cunent ShutdownSetting: PermitssettingB+
current shutdownpoint without disturbingexternalload
connectionsor output voltagesettings;does not require
applicationof short circuit to output terminals.sirirply
pressthe button and adjustthe CURRENTSETcontroitb
the desiredsettingon the currentmeter.
O400V,G200mA: Outputvoltagecontinuouslyadjustable
over.entire-rgnge
wjth g singlecontrol;no rangeswitching
required.Fully regulatedoutput at all levels.
G100V, G2mA: Output voltagecontinuouslyadjustable
gver.entire rang€ with a singlecontrol; indepehdently
tloatingoutput. Canbe usedindependently
of the 0400V
oglpgt or canbe usedwith eitherpolarityreferenced
to the
400V output.
6.3VAC,I2.6VAC CT, G3.5A: Independently
floatingAC
sources.
6.3VAC(Non-Adjustable)
OutputVoltage:
FEATURES
Dual Meters: Allow B+ supply output voltage and B+
supplycurrent drain to be monitoredsimultanebusly.
The
voltmetercan alsobe switchedto monitor the biasiupply
voltage.Both metershaveoverloadprotectionto prevent
damagefrom excessive
loading.
one current Range: Simplifies current shutdownsetting
by requiringonly oneadjuitment.
Two Voltmeter Ranges:0-400Vand Gl00V rangesfor the
B+ and C: suppliesrespectivelyprovide maximu=m
resolution with a minimumeffort to the user.
Standby-DCOn Switch:Disconn€cts
the DC suppliesfrom
externalloads without disturbingvoltageor iurrent settings.
Pilot- Lamp: Lights up to indicate at a glance that the
supplyis on.
Mechanicalhe-Regulator: B+ supply rectifier voltage is
increased
in progressive
stepsas output is increasea.
inis
improvesefficiencyas lesspower is convertedto heat at
low voltageoutput.
Floating outputs: Permit referencingthe positiveor negative outp_ulsof the-B+ supply and the C- supply to any
externalDC potentialor grounds.
Reverse?olarity hotection: Preventsagainst accidental
damagefrom reversepolarity connectionsto an external
powersource.
Attractive, Functional tlesign: Permits stacking
- of units
whenmorethanonepowersupplyis required.
E"ry t9. Ope_rate:
All controlsare identifiedand easyto
rgad- Simplifiedoperationhelps
- preventoperatormistakes
that might damageequipment.
INTRODUCTION
Following is a list of some of the most popular applications
of 1602:
o Service Technicians: Powering high voltage solid state
equipment, or individual circuits consisting of transistors, vacuum tubes or both.
The B & K Precision Model 1602 High Voltage Power
Supply is a versatile,laboratory quality instrument which
pr6vities regulated DC voltages and currents of 0-400V at
bZOOmn and G100V at G2mA; and AC voltages and
currents of 6.3 and I2.6VAC at 0-3.5A. The high performance, operating
^choice- ease, and special features make it an
for most applications requiring a high
excellent
DC power source. It is well'suited for,powering
voltage
-solid
siate circuits, tube type circuits,.and hybrids.
fully
Unlike some supplies,the user can rectify the AC.source
and have 3 indefendent suppliesfor powering digital/analog
circuits, etc.
o Factory Technicians: Powering complete equipment
or individual assembliesduring testing in the factory.
o Engineers and l:boratory Technicians: Powering pro'
totypes and experimentalequipment.
o Electronics Instructors and Students: Laboratgry experiments 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
current during normal.operation. Indicates Bt current
limit when set/resetswitch 3 is pustred.
2. B+ CURRENT SET. Provides adjustment of B* current limit. Continuously adjustable from l0-200mA
output current.
3. B+ CURRENTPUSHTO SET AND RESET(SET/
and held,
RESET)BUTTON:Whenfully depressed
connects
cunentmeter1 fo readtheB+ currentlimit
resetsB+ overload
setting.Whenpressedand released,
circuitif it hasbeentripped.
4. OVERLOAD INDICATOR (RED). Lights when B+
currentlimit hasbeenexceededandthe B+ zupplyhas
strutdown.
5. STBY ON. STBY position: Removespower from
terminals8, 9, 13, and14, and voltmeter10, but
leaves the DC supplies activated and at standby
condition. ON posifion: Applies power to oirtput
terminals8, 9, 13, 14, andvoltmeter10.
6. POWER.Ughts continuouslywhen power supply is
turnedon.
groundterminal7. TERMINAL. Earth andchassis
B+ TERMINALS
8. + TERMINAL. Positivepolarity of B+ output.
9. - TERMINAL. Negativepolarity of B+ output.
10. VOLTMETER.Indicatesoutput voltageof B+ or Csrpplies.
ll. METERRANGE. B+/G400position:Selectsfull scale
ranseof 400voltsfor voltmeter10 to meter$+ output
vollage.C-/G100position: Selectsfull scalerangeof
100f for voltmetei10 to meterC- outputvoltage.
12. LEVEL (B+). Turns off power supply at extreme
rotation.Clockwiserotation turnson
counterclockwise
power supply and adjustsB+ output voltageupwards.
C-TERMINAI,s
13. - TERMINAL. Negativepolarity odtput of C- supply.
14. + TERMINAL. Positivepolarity output of C_supply.
15. C- CONTROL.{,{gsts C- output voltagebetween
terminals13 and 't4 from 0 to-100Vwitf, clockwise
rotation. Output voltage is monitored on Voltmeter 10 when METER RANGE Switch 1l is in
C-lGl00Vposition.
16.& 17. 6.3VACTERMINAIS. 6.3VAC output rerminals.Protected
by breaker19
16.& 18. 12.6VAC TERMINALS. l2.6VAC output terminals.Protectedby breaker 19
19. AC RESET. Circuit breakerin serieswith terminal16
protectsagainstexcessive
overloadsbetweenterminals
1 6 , 1 7a n d 1 6 , 1 8 .
NOTE: At17 and18 6.3VAC is available.This output is
protected by an internal fuse. For maximum
convenience and minimum down-time due to
accidentalshort-circuitsuse the breaker-protected
A C outputs16 , 17 and 16, 18.
OPERATING INSTRUCTTONS
l.
Turn off the power supply before pluggingit into an
AC outlet, by rotating the LEVEL control 12 fully
counterclockwise,until it "clicks" off.
(b) Push the SET/RESET3 button in and adjust
the B+ CURRENT SET 2to at least50mA on
CURRENT METER 1 if not already,and reset
to the desiredcurrentlimit.
2. Connectthe power cord to a 105-125volt 60 Hz AC
outlet.
(c) Releasethe SET/RESET3 button and return
STBY/ON 5to ON postiition..
WARNING
a. Use only a polarized3-wire outlet. This assures
that the power supply chassisis connectedto a
good.earth.ground and preventsdangerfrom
electrical shock. lf a 2-wire to 3-wire-adapter
m_ustbe used, be sure the ground wire of the
adapteris attachedto a good earth ground.
b. If a circuit under test requiresapplicationof a
fixed bias, always apply the required voltage
usingthe_C-supp-lyfirst; before applying the Ii'+
voltage(Step 6-d).
4.
Turn gn-lhr_ qower supply by rotating the LEVEL
control 1Z slightly clockwise past
the-.,click". The
POWERindicator 6 will light.
Determine the maximum safe load current for the
device to be powered and set the automatic current
strutdownfor that valueas follows:
a. Pushand hold the set/resetbu_tton3 and adjustthe
B+ CURRENT SET control 2 for the desiredshut_
down current point as read on the CURRENT
meter 1 .
b. Releasethe set/resetbutton 3 .
c. Turn LEVEL (B+) control 12
voltage.
to the desired
d. If the maximum safeload current is unknown. start
with a low current setting.If the settingis too low,
the overloadcircuit will trip when pow6r is apphed
t o t he loa d i n s te p s6 a n d 7 .l fi o , i n creai r' tf,.
current_setting in small steps until the overload
circuit doesnot trip during normal operation.
NOTE
In certain conditions of high-line voltagesor B+
OUTPUT. voltages gre,aterihan 100V,-resetting
rygy.not be accomplishedby simply pushing thJ
SET/RESET
3 buttbn.(ThisisOuet6 the qr-"VCE
sensingcircuitry described
underCURRENT-VCE
SENSINGCIRCUITS,page13.)Shouldthisoccur
proceed
asfollows:
(a) Set the STBY/ONS switch to the STBY
position.
If an overload in the circuitry being powered
exists,the supply will shutdown as normal.
At very low output currents, decreasingthe B+
output voltage between l50V to 400V may
activate the QI-VCE sensingcircuit before the
desiredB+ output is reachedon VOLTMETER 10.
The supply will shutdown and the OVERLOAD
lamp 19 will light. To reset, simply proceed as
statedin (a), (b), and (c) above.
5.
Connect the. powe_rsupply output to the devicebeing
poweredwith test leadsas follows:
a. connect th9 positivepolarity high voltageinput of
the device being powered to the (+) teririnaf 8 of
the B+ supply.
b. Connectthe negativepolarity high voltageinput of
the device being powered to the (-) terminaf g of
the B+ supply.
c. If the positivepolarity of the devicebeingpowered
is to be^the ground reference,j_lrmpei
the . (+)
terminal 8 to the ground terminal 7 .
If the negativepolarity of the devicebeingpowered
is to be^the ground reference,conneJt^the
o
terminal 9 to the ground terminalT.
If neither the positiveor the negativepolarity input
of the devicebeing poweredneedsto be grouniled
but the chassis of the device needs grounding,
connect a separatetest lead from the chassisof the
device to the ground terminal 7 of the B+ supply.
d. Follow the.above proceduresfor the C_ supply,
u.silg^plus (+) terminal 14 and minus (-) teiririir_
13.
NOTE
Ih.r C- -supply and the B+ supply are entirely
independentof eachother. Whena iircuit requires
a.biasvoltagewhich is negativewith respectto the
circuit reference,the (+) terminal 14- of the Csupply is connectedto this reference.Refer to Fie.
2.
e. C onnect the A C vol tage source s ( t er m in_
als 16 , 17 andlor 1G , 18lto the device if ;;_
quired.
srG
T N
H
H6Bm"
Flg. 2. Typical Vacuum Tube Circuit Application.
(3) lncrease the strutdown point slightly with the
6. Return the STBY-ONSwitch 5 to the ON position
andsetthe outputvoltageasfollows:
a. Set METER RANGE Switch to C-l0-100V when
adjustingC- supplyoutput.
b. Turn C- control 15 until desiredvoltageis reached.
7.
B+ CURRENT SET control 2 .lt the normal
load current is unknown, this techniquemay be
used, but, if the current limit is already set for
the maximum safeload current, do not increase
the current limit further.
c. Set the METER RANGE switch 11 to B+/G400V
when adjustingB+ supply output .
(4) Check the bias setting to determine if it is
d. Turn LEVEL control 12 clockwise until voltage is
reached.
(5) Refer to NOTE under 4d, Page5.
incorrectly set.
NOTE
NOTE
When a fixed bias is required for a circuit under
test, always perform Steps a and b first. (C- bias
level.)
Some equipment has a highly capacitive input,
which results in a surge current when power is
initially applied. When powering such equipment,
the overl,oad circuit may activiate when the
STBY-ON switch is placedin the ON position with
full operatingvoltagepreviouslyset. If this occurs,
reduce the voltage setting before resetting the
overload and then bring the output level up
gadually to allow the capacitorsin the equipment
to charge;this eliminatesthe surgecurrent.
If the B+ load current exceedsthe current shutdown
point, the overload lamp 4 will light, and the B+
supply will shut down (cunent meter 1 and voltmeter 10 will drop to zero). Restorethe power supply
to normal operation as follows:
a. To reset the power supply, press and releasethe
set/reset button 3 . If the overload was intermittent, this will restorenormal operation.
b. If the overload lamp remains lit, use one of the
following techniques before resetting the power
supply again.
(l)
Reducethe load current.
(2) Reduce the voltage slightly with the LEVEL
control 12 .
c. If the power supply continues to shut dodn at the
correct current setting, check the load circuits to
determinethe reasonfor the overload.
d. To remove power from the load without disturbing
the voltage or current shutdown settings, set the
STBY-ON switch 5 to the STBY position.
e.
Refer to NOTE under 4-d, page5.
APPLICATIONS
General
Connect the B+ lead to the (+) terminal I of the B+
supply to provide power for the plate and screengrid
of the tube.
5. Connect the common lead to the (-) terminal 9 of the
B+ supply. This point is alsonormally connectedto the
ground t6rminal- 7 , for strock hazatd prevention. The
ionnection between ground and the (-) terminal 9 of
the B+ supply
- may not be used during some types of
experimentJ, such as positive grounds and floating
supply inputs.
With the meter switch in the C-/G100V position, adjust the
C- control for the desiredbias level.
4.
This instrument may be used to power a vast assortmentof
circuits and devices in the fields of electronics servicing,
electronics manufacturing, electronics design engineering,
and electronics education. The l+ and C- supply outputs
are fully adjustable over their full range, while the low
voltage AC iource remains fixed. This flexibility makes it
suitable for most applicationsrequiring a singleor multiple
output high voltage supply.
Powering Tube Type Circuits
Fig.2 shows the 1602 being used to supply the operating
voltagesin a typical vacuum.tubeRF amplifier stage.
l.
Connect the filament of the tube to terminals 16 and
17 for 6.3VAC heater operation or to 16 and 18 if
l2.6VAC heatervoltageis required.
2.
Connect the grid resistor to the (-) terminal 13 of the
C-supply.
3.
Connect the (+) terminal 14 of the C- supply to the
(-) terminal 9 of the B+ supply.
t-)
Before the S+ output voltage is adjusted, press the B+
current set/resetbutton and adjust the B+ CURRENT SET
control for the maximum output current desired.Now the
S+ voltage level may be increasedto the required level-If
the current overload circuit shuts down the B+ output,
either increasethe B+ current set, or decreasethe output
current drain by increasing the C- output voltage. (Also
refer to NOTE under 4'D, Page5.)
\
SIG OUT
I
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g6:gB6Em"
Fig. 3.
Typical Triinsistor Circuit Application.
Powering Transistor Type Circuits
Fig. 3 showsthe 1602 Power Supply being used to power a
transistofamplifier circuit.
l.
2.
Connect the Vcc lead of the circuit to the (+)
terminal 8 of the B+ supply.
Connect the common lead of the circuit to the (-)
terminal 9 of the B+ supply and to the ground
terminal 7.
In some circuits the chassisis connectedto the positive Vcc
line which meansthe ground terminal should be connected
to the (+) terminal 8 of the B+ supply. Fig. 4 shows the
various methods to connect the 1602 to accommodate
different equipment power/ground configurations.If there
is any doubt which supply lead is common to the chassis,
no damagewill result if a separatelead is connectedfrom the
chassisto the ground terminal 7 .
EQUIPI\4ENT
BEING
POWERED
EQUIP},IENT
BEING
POWERED
Fig.4.
Power Supply Output Situation.
Other Educational Uses
The student in an electronics course may use the power
supply for powering equipment and circuits as previously
describedfor all other applications.In addition, the power
supply can be used to conduct experimentsin fundamental
electronics.In learningOhms law, for example,the relationstrips of resistance,voltage and current are easily demonstrated with the supply. Being able to observeboth voltage
and current simultaneously is a geat aid in such experiments. 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. Additional 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
Although two supplies may be used safely in the above
situations, it is not recommended that the supplies be
operated in seriesfor voltageshigher than 400V. Also, to
avoid shock hazards,do not connect both ground terminals
to the power supply output terminals; doing so may place
the entire power supply chassisat a high potential.
OBSERVE
CHARACTERTSTIC OF DIODE
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BASIC CURRENT DIVTDER
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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
regulated and filtered DC output that is fully adjustable
from 0 to 400 volts at G200mA at the B+ terminals; and
G100V at 0-2mA at the C- terminals. The supply also
convertsits AC input to a l2.6VAC center-tappedoutput
at G3.5A. The circuits that accomplishthis action may be
divided into 4 main groupsas follows:
l.
UnregulatedDC and AC sources:Converts the AC
input to raw DC for the B+ and C- control and filter
circuits; and stepsdown the AC input for the l2.6VAC
filament windings.
2.
Control circuits: Control the unregulated B+ and Csources to provide the highly regulated, adjustable
outputs.
3.
Current sensingcircuits: Establishthe B+ current limit,
sensethe B+ load current, and activate an overload
detector that shuts down the B+ supply if the current
limit is exceeded.
4.
Metering: Monitors the B+ or C- voltage, and the B+
output current. Refer to Fig. 7,the functional diagam
and to the schematic diagram. Circuit descriptions
make constant referenceto thesediagrams.
NOTE: The voltagesin the following circuit descriptions
and on the diagrams are measuredwith respect to the
regulatedB+ output, the + terminal, or the C- output, and
- terminal. Note that these points are floating independently of the chassisof the power supply.
The C- and CONTROL unregulated DC sourcesare fairly
standardand straightforward.
Secondary winding No. 2 provides power for the comparator ICI and voltagereferenceand error amplifier IC2.
This supply is designedto be free of influence from the
unregulated B+ supply. The 20 volt AC output from
secondarywinding No. 2 is convertedto +15V and -15V by
full wave,rectifiersDl and 2. Both the V+ and V- voltages
float with respectto the regulatedoutput and the unregulated B+ supply variations.
Secondarywinding No. 3, diode D9 and Cll provide half
wavefiltered DC for the C- control and filter circuits.
B+ and C- Control Circuits
The B+ control circuit converts the unregulatedB+ supply
into the regulated l+ output voltage. The control circuit
establistresthe regulated B+ output voltage in responseto
the setting of the LEVEL control R22. When R22 is set for
0 volts, the following circuit conditions exist:
l.
")
The unregulated B+ output level is pre-regulatedin coarse
steps.As the LEVEL control is rotated clockwisefrom zero
to maximum,the unregulatedB+ changesfrom its lowest to
its highestvaluein four steps.This minimizes the difference
between the unregulated B+ and the regulatedB+ output,
which alwayskeepspower dissipationwithin safelimits.
The main components which make up this circuit are
winding No. 1 of power transformer Tl, pre-regulator
switch assembly 52, rectifiers D5, 6, 7, 8, and filter
capacitorC8.
The AC input is applied to the unregulated B+ circuit
through on-off switch 54 (which is part of the level
control) acrossneon lamp NEI (which glows continuously
as a pilot lamp to show that power is on) to power
transformerT1.
TransformerTl has four taps in its output winding No. l.
At the lowest voltage setting, only the low voltageportion
of the winding is connected to the rectifiers (this is the
condition shown on the schematicdiagram).As the LEVEL
control is rotated clockwise,cams operatemicroswitches
S2C, then S2B, and finally S2A. Each cam-operated
microswitch selectsanother tap on this secondary of the
transformer and sequentially steps the rectifier input
voltageto a higher value.
Rectifier diodesD5, 6, 7, and 8 convert the AC to full wave
DC, which is filtered by C8. The unregulated!+ output at
C8 is regulatedand filtered by the control circuits.
The +7V referenceis divided acrossRlO and Rl l to
place +3.5V at pin 4,IC2, the invertinginput of error
amplifier IC2B.
3. The regulatedB- voltageis 0V.
4. The +7V reference is divided across current Path I,
which consistsof R23, Rl2, R30, and R2l (R22 is
approximately 0 ohms at this time). This places
approximately +3.5V on IC2-5, the non-invertinginput
of error amplifier lC2-13.
Unregulated DC and AC Sources
There are three unregulatedDC sourcesand one unregulated AC source in the supply. The most important
unregulated supply is the B* source.This source converts
I ITVAC to a raw unregulatedB+ output. Later, the control
and filter circuits convert this to the regulatedB+ output of
the power supply.
Voltage referencelCzA providesa stable+7V reference
atlC2-6.
5 . Error amplifier lC2B will produce whatever output is
necessaryto keep the difference voltage at its inputs,
pins 4 and 5, very close together.Therefore,with R22
at about zero ohms, just enough drive will be applied
to seriespassregulatorQl, Q2 to maintain a zero volt
B- output.
6.
The seriespass transistors are being slightly driven at
0V output to avoid non-linearities at low output
voltages(iumps in output, poor regulation,etc.).
When LEVEL control is increasedto a higher voltage level
the following circuit action occurs:
1. The resistanceof R22 is added to the voltage divider
network, decreasing
current I1.
2.
The voltage at lC2-5 increases(less drop acrossR23,
l2), and error amplifier IC2B increasesits output to
drive seriespasstransistor Q l, Q2 into heavierconduction.
3.
The regulator allows some of the B+ supply to passto
the output, and the output voltagerises.
4.
As the output voltagerisesthe B- supply becomesmore
negativewith respectto the B+ terminal.
5.
Current I increasesas the B- becomesmore negative,
and the voltage at IC2-5 decreasesuntil balance is
achieved.
the oppositeaction
When LEVEL control R22 is decreased,
occurs. Once R22 is set and balanceis achieved,any load
current changesthat tend to changethe output voltageare
sensedand corrected.
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The C- control circuit converts the unregulatedC- supply
into the regulated C- output voltage. This control establistres the output level in responseto the setting of the
BIAS control, R35.
The voltage referencefor this circuit consistsof D2l ,C14,
and R34. Referencediode D21 acts as a constant voltage
sourcefor R35. The wiper of R35 is connectedto the base
of Q3, so the output voltage will always be .6V less than
the control setting. Any variations in the unregulated Cvoltage are absorbed across R34, becauseas the voltage
acrossD21 increasesabove its referencevoltage, its internal resistancedrops to draw more current.
fu 12 increases,the voltage drop acrossR34 also risessuch
that the reference voltage stays constant. Diode D2l is
biased so that its voltage never drops below its reference
point.
If the load on the output increases,the output voltagewill
attempt to drop. This will turn Q3 on harder, increasingthe
output current, which restoresthe output voltage.
The oppositeeffect occursas the output load decreases.
Overloaddescription: Resistance-limited.
Current-VCE SensingCircuits
The main components in the current sensing circuits are
comparator ICl, overload switch SCR-1, and current sense
resistor Rl. This circuit monitors the B+ load current and
sttuts down the B+ supply if the load current is exceeded.
The current sensingresistor, Rl, is selectedso that IV is
developed across it when exactly 200mA load current is
drarvn. The voltage across this resistor is applied to the
non-invertinginput of the comparator,ph 2,lcl.
The inverting input, ph 3, is connectedto a variable 0-1V
voltagesource,R5, the Bf current limit control.
Wheneverthe output load current producesa voltageacross
Rl that is greater than the preset voltage on the inverting
input of the comparator, ICl, a positive lV signal appears
at output pin 7. This output drives the gate of overload
switch SCR-I and turns it on. SCR-I groundspin l0 of
error amplifier IC2B, which inhibits its operation regardless
of all other inputs, shutting down the power supply. SCR-l
also provides the ground path which allows the overload
lamp to light. Set/reset switch 53 shorts across SCR-I,
when it is depressed,to replacethe current path.
NOTE
Besidesthe current-sensingfunction, another circuit comprisedof R40, D25,D24, and Rl7 senses
the collector-emitter voltage of Ql above 200V.
During overloads and some reset conditions the
value of the collector-emitter voltage and the
collector-current of Ql can shift the operating
point of Ql out of its S.O.A. (Safe Operating
fuea) curve. The avalanchebreakdown of D25 and
D24 is such that for collector-emitter voltages
geater than 200V, a voltage is developedacross
R17 that adds to the voltage developedby the
output current acrossRl. This summedvoltageon
pin 2 of ICl represents an equivalent power
dissipation value that is under the S.O.A. curve of
Q1. Therefore, when this summedvoltage reaches
the preset voltage on pin 3 of ICl, a strutdownof
output voltageand current occurs.
Metering
Voltmeter Ml is connected directly acrossthe output of
the B+ supply or the C- supply, to measureoutput voltages.
Meter Range switch M selects the proper input and the
proper series resistor to calibrate the meter for either
G400V full scale,or G100V full scale.
Current meter M2 is actually a voltmeter calibratedto read
S+ output current. The meter measuresthe voltage developed acrossthe current sensingresistor,which is exactly I
volt for a full scalemeter reading.When setting the current
limit, switch 53 is actuated, which connects the current
meter directly acrossthe B+ current set control R5. This
control selectsa voltage from GlV, which very accurately
correspondsto the current limit value read on the meter.
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
This power supply is built to provide long, trouble-free
serviceand does not require periodic maintenance.If the
unit malfunctions, use conventional troubleshootieg techniques, such as voltage and resistor checks to isolate the
defective component. If defectivecomponentsare replaced
the unit should be recalibrated.A note on safety: Whenever
servicing this unit keep the level control R22 below one
third rotation (no microswitches activated) to keep the
maximum DC voltage below l60V DC. Rememberthat the
pre-regulator
cansupplyup to 500VDCto theboard.
CALIBRATION
Use insulated adjusting tool, and exercise CAUTION- the
P.C.B.has over 400V DC potential at maximum settings.
To gain accessto the calibration adjustments, remove the 3
screwsat the rear of the top cover, then lift the top cover at
the rear and slide the front lip of the cover from the
retaining bosseson the front panel. Refer to Fig. 8 for
locations of calibration adjustments.
l3
l00v METERCAL (R26)
l. Connect an accurate,calibratedvoltmeter to the
output terminals13 and 14 , capableof l00V reading2.
3.
Set the METER RANGE switch 11 of the power
supply to the C-lG100 position.
Adjust the C- control 15 for exactly 100V on the
externalvoltmeter.
4. Adjust l00V CAL potentiometer(R26) for exactly
l00V on thevoltmeterof the 1602powersupply.
fl,'
MAX. OUTPUTADJ. (R23)'
1 . Connect an accurate,calibratedvoltmeter to the
outputterminalsSand 9, capableof 400V reading.
Set the LEVEL control 12 of the 1602powersupply
to MAXIMUM.
(R23)
3 . Adjustthe MAX. OUTPUTADJ.potentiometer
for exactly402Volts on the externalvoltmeter.
100v
METER
CAL
CURRENT
METER
CAL
400v METERCAL (R3l)
l. Connect an accurate,calibratedvoltmeter to the
output terminals8 and 9 , capableof 400V reading.
2. Set the METER RANGE switch 11 to the 0-400
positlon.
MAX
OUTPUT
ADJ
Fig. 8.
Location of Calibration Adjustments
and Fuses.
3. Setthe LEVEL control 12 of the 16O2powersupply
to readexactly400 Volts on the externalvoltmeter.
4. Adjust 400V CAL potentiometer
(R3l) for exactly
400 Volts on the voltmeterof the 1602powersupply.
CURRENTMETERCAL (R27)
l. Refucethe 1602LEVELcontrol 12 to minimum.
2. Connectan accurate,calibratedammetercapableof
200mA in serieswith an appropriateload (250 ohms,
l0 watts) to the output terminals8 and 9 of the
1602powersupply.
3. Adjpst the LEVEL control"12 for exactly200mAon
the externalammeter.
4. AdjustCURRENTMETERCAL. potentiometer
(R27)
for exactly 2OOrnAon the currentmeterof the 1602
powersupply.
CLTRRENT
LIr\ilrTADJ (R39)
LIMIT
I CAL
400v
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
MCtEr.ROtAtEB+ CURRENT SET C.C.W. UNtiI
"OVERLOAD"
LIGHTS. Press button 3 to
check accuracy. If OVERLOAD DOES NOT
LIGHT, CURRENT LIMIT CIRCUIT IS BAD.
Also refer to NOTE under 4d, page 5.
FUSE REPLACEMENT
If there is no power supply output, and the POWER lamp
does not light, check fuse Fl. If the POWER lamp lights,
but there is no output from the main 400V supply, check
FuseF2.
If the POWER lamp lights, but there is no I2.6VAC output
after resetting 18 on the 1602 front panelcheckF-3.
NOTE: No loadconnected
for this adjustment.
All fusesare 3AG pigtail type, and locations shown in Fig.
8.
l. Set 2 adjusted
to full C. W.
2. Pressbutton 3 and adjustR39 for exactly200mAon
the current meter of the 1602 power supply,then
release
button 3.
All fuses are accessibleby removing the top cover. To do
this, remove 3 screwsat the rear, lift the top cover at the
rear, and slide the front lip of the cover from the retaining
bosseson the front panel.
I4
l
WARRANTY SERVICEINSTRUCTIONS
+
1.
Refer to the MAINTENANCE section of your B & K-Precisioninstruction manual
for adjustmentsthat may be applicable
2.
If the above-mentioned
proceduresdo not correctthe problemyou are experiencing
with your unit, pack it securely(preferably in the origihal carton or doubli-packed)l
Enclosea letter describingthe problem and include four name and address.Deliver
to, or ship PREPAID ([IPS preferred) to the neaiest B & K-Precisionauthorized
serviceagency(seelist enclosedwith unit).
If your list of authorized B & K-Precisionserviceagencieshas been misplaced,contact
your local distributor for the nameof your nearestseiviceagency,or write-to:
Service Deprtment
B & K-PrecisionProduct Group
DYNASCAN CORPORATION
6460 WestCortland Street
Chicago,Illinois 60635
LIMITED ONE.YEAR WARRANTY
DYNASCAN CORPORATION warrants to the original purchaserthat its B & K-PRECISION
product, and the component parts thereof, will be free irom defectsin workmanshipand materials
for a period sf one year from the date of purchase.
DYNASCAN will, without charge,repair or replace,at its option defectiveproduct or component
-or
parts upon delivery to an authorized B & K-PRECISIONservicecontractor
the factory iervice
department,accompaniedby proof of the date of purchasein the form of a salesreceipt.
To obtain warranty coverage,this product must be registeredby completing and mailing the
enclosedwarranty registrationcard to DYNASCAN, B & K-PRECISION,646b West Cortland Slreet.
chicago,Illinois 60635 within fifteen (15 days) from the date of purchase.
Exclusions: This warranty does not apply in the event of misuseor abuseof the product or as a
result of unauthorized alterations or repairs. It is void if the serial number is alterid. defaced or
removed.
DYNASCAN shall not be liable for any consequentialdamages,including without limitation
damagesresulting from loss of use. Some statesdo not allow limitati,onof incidentalor consequential
damages,so the abovelimitation or exclusionmay not apply to you.
This warranty givesyou specificrights and you may alsohaveother rights which vary from state
to state.
For your conveniencewe suggestyou contact your B & K-PRECISIONdistributor, who may be
authorized to make repairs or can refer you to the nearestservicecontractor. If wairanty ,"rui".
cannot be obtainedlocally, pleasesendthe unit to B & K-PRECISIONServiceDepartment,6460 west
Cortland Street,Chicago,Illinois 60635, properly packagedto avoid damagein shipment.
-\
DYNASCAN
COFlPOF|ATION
6460 West Gorflond Street
Chicogo, lllinois 60635
o1980 o DYNASCANCORP.
480.152-9-001G
PRINTEDIN U.S.A.