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Errata
Title & Document Type: 6433B DC Power Supply Module Operating and Service Manual
Manual Part Number: 06433-90001
Revision Date: January 1966
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OPERATING AND SERVICE MANUAL
MODEL 64330
DC POWER SUPPLY
MANUFACTURING CODE 6A
January,
19
66
TABLE OF CONTENTS
Section Title Page
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3-3 8 Operating Considerations
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TABLE OF CONTENTS (cont
.
)
Section
IV
Title Page
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P e r f o r m a n c e c h e c k
Rated Output and Meter Accuracy
Additional Specification Check
5.51 Adjustments and Calibrations
Constant Voltage Programming Current
Constant Current Programming Current
TABLE OF CONTENTS (cont
.
Section T i t l e Page
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Bias and Reference Line Regulation
. . . . . . . . . . . . . . . . . .
Constant Current Load Regulation
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iii
MODEL
6433B
REVISION:
Please note the following changes in the instruction manual:
1, Wherever 64334 appears, change it to 64338.
2. Eliminate the 10A fuse and holder in the ACC side of the line.
3. Change voltage rating from 32 volts t o 36 volts.
4, Change T 1 from 643391 t o 643391B.
5. Change C13 and C17 from 47, OOOpf 40VDC to
40,000pf 50VDC Mfg, Part
#
D42343.
6, Change R21 from 160 ohm
7, Remove C12 from AC lead
2W.
2W
t o 43 ohm
-- move to
ACC (anode of CR18).
8, Change Q1,2,3,4,6,8,9 from 2N3390 to
2N3391 Corporate Part
#
1854-0071.
J
INPUT:
RATED OUTPUT:
LINE REGULATION:
LOAD REGULATION:
RIPPLE AND NOISE:
OPERATING TEMPERATURE RANGE:
STORAGE TEMPERATURE RANGE:
TEMPERATURE COEFFICIENT:
OUTPUT STABILITY:
(after 30-minute warm-up)
REMOTE PROGRAMMING:
OUTPUT INDUCTANCE:
Table 1-1
.
Specifications
TYPICAL OUTPUT IMPEDANCE:
105-125 vac, 57 t o 63 c p s , s i n g l e phase,
7
amperes, 450 w a t t s max
.
Constant Voltage: 0 t o 32 vdc.
Constant Current: 0 t o 10 amperes d c
Constant Voltage: L e s s than 18 mv for
105-125 v a c input change.
Constant Current: L e s s than
1
105-125 v a c input change.
C o n s t a n t Voltage: Less t h a n 36 mv for 0 t o
Constant Current: L e s s thari 100 ma for 0 t o
3 2 vdc load c h a n g e .
32 mvrms
O°C t o 50°c
-20°C t o 71%
Constant Voltage: 0.05% plus 8 mv per d e g r e e centigrade.
Constant Current: 30 ma per degree centigrade.
Constant Voltage: 0.15% plus 2Bmv for 8 hours a t c o n s t a n t temperature.
Constant Current:
1
OOma for 8 hours a t c o n s t a n t temperature.
Constant Voltage: 2 00 ohms per volt
*1%
C o n s t a n t Current: 2'5ohms per ampere +10%
L e s s t h a n 0.01 ohm from d c t o 0.5 c p s
L e s s t h a n 0.5 ohm from 0.5 c p s t o 100 c p s
L e s s than 0.2 ohm from 100 c p s t o l k c
L e s s than 1 . 0 ohm from l k c t o 100 k c
1.0 microhenry
r
Table 1-1
.
Specifications (cont .)
TRANSIENT RECOVERY TIME:
SIZE AND WEIGHT:
FINISH:
In constant voltage operation, l e s s than
300 milliseconds is required for output voltage recovery t o within 200millivolts of t h e nominal output voltage following a load change equal t o one half t h e maximum current rating of t h e power supply.
Nominal output voltage is defined a s t h e mean between t h e no-load and full-load voltages. The transient amplitude is l e s s than 0 . 5 volt per ampere for any load change between 20% and 100% of rated output current. (Excluding the initial s p i k e of approximately 100 microseconds dura- tion which is significant only for load r i s e times faster than
0.5 ampere per micro- second
.
)
Heiaht
3 - 1 / 2 i n .
Width
1 9 i n .
Depth
17-1/2in.
Weight
33
lb.
Light gray front panel with dark gray c a s e .
Figure 1-1. Model 6433ADC Power Supply
SECTION I
GENERAL INFORMATION
1 - 2 .
.
DESCRIPTION
GENERAL
1-3. The H-Lab Model 6433ADC Power Supply (fig. 1-1) i s a completely solid- state, compact, well-regulated, constant voltage/constant current d c power supply suitable for either bench or relay rack operation. A three-wire five-foot power cord is provided. The output is continuously variable between 0 and 32vdc, and be- tween
0
and 10 amperes. Detailed specifications are given in table
1-1
.
1-4. OVERLOAD PROTECTION
1-5.
A
crossover feature protects both power supply and load in constant voltage operation. Automatic crossover circuitry switches the power supply from constant voltage t o constant current operation i f the output current exceeds a preset limit.
This crossover circuitry a l s o protects t h e load from overvoltage during constant current operation by automatically switching the power supply into constant voltage operation. The user c a n adjust the crossover point via the front panel controls
(para. 3 -8 and 3-9)
.
1-6.
The power supply is protected from reverse voltage (positive voltage applied t o negative terminal) by a diode that shunts current across the output terminals when this condition e x i s t s . The a c input is fused.
A double-pole on/off switch opens both power leads in the off position.
1-7. COOLING
1-8. Convection cooling is used. No fan is required. The power supply has no moving parts (except meter movement).
1-9. MONITORING
1-10.
Two front-panel meters are provided for monitoring output voltage and current.
The voltmeter has a 0 to
40
volt range and the ammeter has a
0
t o 12 ampere range.
Each meter has a 2% accuracy a t full s c a l e .
1-1 1. OUTPUT TERMINALS
1-12.
Output power is available via a terminal strip on the rear panel. The rear panel terminal strip a l s o enables the power supply t o be connected for different modes of operation (para. 3-3). The output terminals gre isolated from t h e c h a s s i s
and either t h e positive or t h e negative terminal may be connected t o the c h a s s i s via a separate ground terminal located adjacent t o the output terminals. The power supply is insulated t o permit operation up t o
3 0 0 vdc off ground.
1
--
13
.
INSTRUMENT IDENTIFICATION
1-14.
Harrison Laboratories power supplies a r e identified by a three-part designa- tion. The first part is the model number: t h e second part is the serial number: and t h e third part is the manufacturing code letter. This manual applies t o a l l Model
'6433A
power supplies with t h e same manufacturing code letter given in the title page. Change s h e e t s will be supplied with the manual t o make it apply t o Model
6433A
power supplies with different manufacturing code letters.
SECTION I1
INSTALLATION
2
-
1.
INITIAL INSPECTION
2-2.
GENERAL
2-3.
Before shipment, t h e power supply was inspected and found free of mechan- ical and electrical defects. If damage t o t h e shipping carton is evident, a s k that the carrier's agent be present when the power supply is unpacked. As soon a s t h e power supply is unpacked, inspect i t for any damage that may have occurred in transit. Also check t h e cushioning material for signs of severe s t r e s s (may be indication of internal damage). Save a l l packing materials until t h e inspection is completed. If damage is found, proceed a s instructed in t h e Claim for Damage in
Shipment notice on t h e back of the front cover of this manual.
2 -4.
MECHANICAL CHECK
2-5. Check that there are no broken knobs or connectors, that the external sur- face is not scratched or dented, that the meter faces a r e not damaged, and that a l l controls move freely. Any external damage may be a n indication of internal damage.
2
-6..
ELECTRICAL CHECK
2 - 7 .
Check that the straps on the terminal strip a t the rear of t h e power supply are secure and that t h e strapping pattern is in accord with figure 3-2. Check t h e electrical performance of the power supply a s soon a s possible after receipt.
A performance check that i s suitable for incoming Jnspection is given in paragraphs
5 -7 through 5 -2 2
.
2 -8
.
INSTALLATION DATA
2-9. GENERAL
2-10.
The power supply is shipped ready for bench or relay rack (19 inch) opera tion.
2
-
1 1. LOCATION
2-12. Because the power supply is cooled by convection, there must be enough s p a c e along the s i d e s and rear of the power supply t o permit free flow of cooling air. The power supply should b e located in a n area where the ambient temperature does not exceed 50°c.
2 -13.
POWER REQUIREMENTS
2 - 1 4 .
The power supply is operated from a
105
t o
125
volt
(115
volts nominal),
5 7 to
6 3
cps, single phase power source. At 115 volts,
6 0
cps, the full load re- quirement is 450 watts a t 6.5 amperes.
2-15.
POWER CABLE
2
-
1 6 .
To protect operating personnel, the National Electrical Manufacturers
Associa tion (NEMA) recommends that the instrument panel and cabinet be grounded.
This instrument is equipped with a three-conductor power cable. The third conduct- or is the ground conductor and when the cable is plugged into a n appropriate receptacle, the instrument is grounded. The offset pin on the power cable three- prong connector is the ground connection.
2-17.
To preserve the protection feature when operating t h e instrument from a two- contact outlet, u s e a three-prong t o two-prong adaptor and connect the green lead on the adaptor t o ground.
2
-
1 8 .
REPACKAGING FOR SHIPMENT
2-19.
To insure s a f e shipment of the instrument, it is recommended that the pack- age designed for the instrument be used. The original packaging material is re- usable. If i t is not available, contact your Hewlett-Packard field office for packing materials and information.
A
packing carton part number is included in the parts l i s t .
2 - 2 0 .
Attach a tag t o the instrument which specifies the owner, model number, full serial number, and service required, or a brief description of t h e trouble.
PILOT
LIGHT
VOLTMETER ZERO-SET AMMETER
OFF/ON
1
SWITCH
/
/
COARSE SINE
VOLTAGE VOLTAGE
\
Ice
ARsE
FINE
CURRENT CURRENT
1.
TURN O N POWER SUPPLY
2. ADJUST OUTPUT VOLTAGE
3.
4.
5 .
6.
OBSERVE VOLTMETER
SHORT OUTPUT TERMINALS (AT REAR OF POWER SUPPLY) AND ADJUST OUTPUT
CURRENT LIMIT
OBSERVE AMMETER
REMOVE SHORT AND CONNECT LOAD TO OUTPUT TERMINALS
F i g u r e 3-1. C o n t r o l s a n d I n d i c a t o r s
SECTION I11
OPERATING INSTRUCTIONS
3-1. CONTROLS AND INDICATORS
3-2.
The controls and indicators a r e illustrated in figure 3 - 1 .
3 -3
.
OPERATION
3-4. GENERAL
3-5. The power supply is designed s o that i t s mode of operation c a n be selected by making strapping connections between particular terminals on the terminal strip a t t h e rear of the power supply. The terminal designations a r e stenciled in white on the power supply and a r e adjacent t o their respective terminals. The strapping patterns illustrated in this section show neither terminal grounded. The operator c a n ground either terminal or operate the power supply up t o 300 vdc off ground
(floating)
.
3 - 6 .
NORMAL
3-7.
GENERAL. The power supply is normally shipped with its rear terminal strapping connections arranged for constant voltage/constant current, local sens- ing, local programming, single unit mode of operation. This strapping pattern is illustrated in figure 3-2. The operator selects either a constant voltage or a constant current output using the front panel controls (local'programming, no strap- ping changes a r e n e c e ssary)
.
3 - 8 .
CONSTANT VOLTAGE. To select a constant voltage output, proceed a s follows
: a . Turn-on power supply and adjust VOLTAGE controls for desired output voltage (output terminals open). b. Short output terminals and adjust CURRENT controls for maximum output current allowable (current limit), a s determined by load conditions. If a load change c a u s e s t h e current limit t o be exceeded, the power supply w i l l automatically cross- over t o constant current output a t t h e preset current limit and t h e output voltage will drop proportionately. In setting the current limit, allowance must be made for high peak currents whichocan c a u s e unwanted cross-over (refer t o para. 3-40).
%
3 - 9 .
CONSTANT CURRENT. To s e l e c t a constant current output, proceed a s follows : current. a . Short output terminals and adjust CURRENT controls for desired output
b. Open output terminals and adjust VOLTAGE controls for maximum output voltage allowable (voltage limit), a s determined by load conditions. If a load change c a u s e s the voltage limit to be exceeded, the power supply will automatical- ly crossover to constant voltage output a t t h e preset voltage limit and the output current will drop proportionately. In setting the voltage limit, allowance must be made for high peak voltages which can c a u s e unwanted crossover. (Refer t o para. 3 -4 0 .)
3-10. CONNECTING LOAD
3-11.
Two pairs of output terminals are provided on the terminal strip a t the left rear s i d e (facing rear) of the power supply. Either pair of terminals or both may be used. The terminals a r e marked
+ and
-.
A separate ground terminal is located adjacent t o the output terminals. The positive or negative output terminal may be grounded, or neither grounded (floating operation: permitted to 3 0 0 vdc off ground)
.
3-12.
Each load should be connected to t h e power supply output terminals using separate pairs of connecting wires. This will minimize mutual coupling effects power supply. Each pair of connecting wires should be a s short a s possible and twisted or shielded to reduce noise pickup. (If shield is used, connect one end t o power supply ground terminal and leave the other end unconnected.)
3-13. If load considerations require that t h e output power distribution terminals be remotely located from the power supply, then the power supply output terminals should be connected t o the remote distribution terminals via a pair of twisted or shielded wires and each load separately connected t o the rem ote distribution terminals. For t h i s c a s e , remote sensing should be used (para. 3-14).
NOTE
It is recommended that the voltage drop i n the con- necting wires not exceed 2 volts. If a larger drop must be tolerated, please consult a Hewlett-Packard field representative.
3-14. REMOTE SENSING
3-15. Remote sensing is used to ameliorate the degradation of regulation which will occur a t the load when the voltage drop in the connecting wires is appreciable.
The u s e of remote distribution terminals (para. 3- 13) i s a n 'example where remote sensing may be required. Due to the voltage drop i n the load leads, i t may be necessary to slightly increase the current limit in constant voltage operation.
CAUTION
Turn-off power supply before rearranging strap- ping pattern a t the power supply rear terminal strip. If the
- S
terminal is opened while the power supply is on, the output voltage and cur- rent may exceed their maximum ratings and re- sult i n damage t o t h e load. The power supply will not be damaged.
3-16. Proceed a s follows: a . Turn-off power supply and arrange rear terminal strapping pattern a s shown i n figure 3-3. The sensing wires will carry l e s s than 10 ma and need not be a s heavy a s the load wires. It is recommended that sensing and load wires be twisted and shielded. (If shield is used, connect one end to power supply negative terminal and leave the other end unconnected .)
CAUTION
Observe polarity when connecting the sensing leads t o t h e load. b. In order t o maintain low a c output impedance, a capacitor with a mini- mum rating of 20,00Op,fd and 25 vdcw should be connected across the load using short leads. This capacitor must have high-frequency characteristics a s good or better than C17 h a s (see parts l i s t ) . c
.
Turn-on power supply.
3 -1 7. REMOTE PROGRAMMING
3-18. GENERAL. The constant voltage and constant current outputs may be pro- grammed (controlled) from a remote location, The front-panel controls a r e disabled i n t h e following instructions. Changes i n t h e rear terminal strapping arrangement a r e necessary. The wires connecting the programming terminals of t h e power supply t o t h e remote programming device should be twisted or shielded to reduce noise pick-up.
(if shield is used, connect one end t o power supply ground terminal and leave t h e other end unconnected
.)
Remote sensing (para.
3
-
14) may be used simul- taneou s l y with remote programming. However, the strapping patterns shown in figures 3-4, 3-5, and 3-6 employ only local sensing and d o not show the load connections.
CAUTION
Turn-off power supply before rearranging strap- ping pattern a t the power supply rear terminal strip. If the current programming terminals are opened while the power supply is on, t h e out- put current will exceed i t s maximum rating and may result in damage t o t h e load. The power supply will not be damaged. The constant volt- a g e programming terminals have a Zener diode connected internally a c r o s s them to limit t h e programming voltage and thus prevent excessive output voltage.
3-19. CONSTANT VOLTAGE. In t h e constant voltage mode of operation, either a resistance or voltage source c a n b e used for remote programming. For resistance programming, t h e programming coefficient (fixed by the programming current) is
200 ohms per volt (output voltage increases 1 volt for each 200 ohms in s e r i e s with programming terminals). The programming current is adjusted t o within 1% of 5 ma a t t h e factory. If greater programming accuracy is required, change R39 (shunt).
The programming resistance should b e a stable, low noise, low-temperature ( l e s s than 30 ppm per
OC) resistor with a power rating a t l e a s t 10 times i t s actual d i s s i - pation.
3-20.
The output voltage of the power supply s,hould be 0 t 2 0 mv, -100 mv when the programming resistance ing
R 6
is zero ohms. This tolerance can be improved by chang-
.
For further information on improving this tolerance, refer t o paragraph 5 -63 and t o H-Lab Tech Letter
# l .
3-2 1. If t h e resistance programming device is controlled by a switch, make-before- break contacts should be used i n order t o avoid momentary opening of the program- ming terminals, To connect the remote programming resistance, arrange rear terminal strapping pattern a s shown in figure
3-4.
The front-panel VOLTAGE controls a r e disabled when t h e strap between A6 and A7 is removed.
3-22. If a voltage source is used a s the remote programming device, t h e output voltage of t h e power supply will vary in a 1 t o 1 ratio with the programming voltage.
The load on t h e voltage source will not exceed 25 microamperes. To connect the programming voltage, arrange rear terminal strapping pattern a s shown in figure
3-5.
3 -23
.
CONSTANT CURRENT. In constant current operation, resistance program- ming is used. The r e s i s t ~ c e current) is
25ohms per ampere (output current increases 1 ampere for each 2 5 ohms in s e r i e s with programming terminals). The programming current is adjusted t o within approximately 10% of
4
ma a t the factory. If greater,programming accuracy is required, change
R41
(shunt). The programming resistance should b e a stable, low noise, low-temperature ( l e s s than 30 ppm per OC) resistor with a power rating a t l e a s t 10 times its actual dissipation.
3-24. The output current of the power supply should be 0
t
50 ma, -1:OO ma when the programming resistance is zero ohms. This tolerance can be improved by chang-
5-6
7 and t o H-Lab Tech Letter
#l
.
3-25. If the resistance programming device is controlled by a switch, make- before-break contacts should be used t o avoid momentary opening of t h e program- ming terminals. To connect the remote programming resistance, arrange rear termin- a l strapping a s shown in figure 3-6. The front-panel CURRENT controls are disabled when the strap between
A 1
and
A2 is removed.
3
-2 6 .
PARALLEL
3-27. GENERAL. Two or more power supplies can be connected in parallel t o obtain a total output current greater than that available from one power supply.
The total output current is the sum of t h e output currents of the individual power supplies. Each power supply c a n be t urned-on or off separately. Remote sensing
(para. 3
-
14) and programming (para. 3 -17) c a n be used; however, the strapping patterns shown in figures 3-7 and
3 - 8
employ only local sensing and programming.
3-28. NORMAL. The strapping pattern for normal parallel operation of two power supplies is shown in figure 3-7. The output current controls of each power supply c a n be separately s e t . The output voltage controls of one power supply (master) should be s e t t o the desired output voltage; the other power supply (slave) should be s e t for a slightly larger output voltage. The master will a c t a s a constant voltage source; the slave will a c t a s a constant current source, dropping i t s output voltage t o equal t h e master's.
3
-2 9
.
AUTO-PARALLEL. The strapping patterns for auto-parallel operation of two and three power supplies are shown in figures 3-8A and B, respectively. Auto- parallel operation permits equal current sharing under a l l load conditions, and allows complete control of output current from one master power supply. The output current of each slave is approximately equal t o the master's. Because the output current controls of each slave is operative, they should be s e t to maximum to avoid having the s l a v e revert t o constant current operation: this would occur i f the master output current setting exceeded t h e s l a v e ' s .
3-30. SERIES
3 -3 1. GENERAL. Two or more power supplies can be connected in series t o obtain a total output voltage higher than that available from one power supply. The total output voltage is t h e sum of t h e output voltages of t h e individual power supplies.
A single load c a n be connected across t h e series-connected power supplies or a separate load can be connected across each power supply. The power supply h a s a reverse polarity diode connected internally across the output terminals t o protect the power supply against reverse polarity voltage if the load is short-circuited or if one power supply is turned off while i t s s e r i e s partners are on.
3-32. The output current controls of each power supply a r e operative and t h e cur- rent limit is equal t o t h e lowest control setting. If any output current controls a r e s e t t o o low with respect t o t h e total output voltage, the s e r i e s power supplies will automatically crossover t o constant current operation and t h e output voltage will drop. Remote sensing (para. 3-14) and programming (para. 3- 17) c a n b e used; however, t h e strapping patterns shown i n figures 3-9 and 3-10 employ only local sensing and programming.
3-33. NORMAL. The strapping pattern for normal s e r i e s operation of two power supplies is shown i n figure 3-9. The output voltage controls of e a c h power supply must b e adjusted t o obtain t h e t o t a l output voltage.
3 -34. AUTO-SERIES. The strapping patterns for auto-series operation of two and three power supplies a r e shown i n figures 3-10A and B, respectively. Auto-series operation permits c o n t r o l of t h e output voltage of s e v e r a l power supplies ( s l a v e s ) from o n e master power supply. The master must b e the most negative power supply of t h e s e r i e s . To obtain positive and negative voltages, t h e
+ terminal of t h e mas- ter may b e grounded. For a given position of t h e s l a v e output voltage controls, t h e total output voltage is determined by the master output voltage controls. The output voltage controls of a s l a v e determines t h e percentage of t h e total output voltage that t h e s l a v e w i l l contribute. Turn-on and turn-off of t h e s e r i e s is controlled by t h e master. In order t o maintain t h e temperature coefficient and stability specifica- t i o n s of t h e power supply, t h e external r e s i s t o r s shown i n figures 3-10A and B, should b e stabie, low-noise, low-temperature
(less than 30 ppm per OC) r e s i s t o r s .
The value of t h e s e r e s i s t o r s is determined by multiplying t h e output voltage of t h e applicable s l a v e by t h e programming coefficient (2 00 ohms/volt)
.
3 -3 5
.
AUTO-TRACKING
3-36.
The strapping patterns for auto-tracking operation of two and three power s.,:!eration permits t h e output voltages of two or more power supplies t o b e referenc- ed t o a common buss; o n e of t h e power s u p p l i e s (master) controls t h e magnitude of t h e output voltage of t h e others (slaves) for a given position of t h e s l a v e output voltage controls. The master must be t h e most negative power supply in t h e group.
The output voltage of a s l a v e is a percentage of t h e master output voltage. The output voltage controls of a s l a v e determines t h i s percentage. Turn-on and turn- off of t h e power supplies is controlled by t h e master. Remote sensing (para. 3-14) and programming (para. 3
-
17) c a n be used; however, t h e strapping patterns shown in figure 3 -4 employ only l o c a l sensing and programming.
3-37.
The v a l u e of t h e external r e s i s t o r s shown i n figure 3-11 is determined by dividing t h e voltage difference between t h e master and t h e applicable s l a v e by t h e programming current (nominally 5 ma; refer t o para. 3-19). Finer adjustment of t h e s l a v e output voltage c a n be accomplished using t h e s l a v e output voltage controls.
In order t o maintain t h e temperature coefficient and stability specifications of t h e power supply, t h e external r e s i s t o r s should b e s t a b l e , low-noise, low-temperature
( l e s s than 30 ppm per OC) r e s i s t o r s .
3 -3 8 .
OPERATING CONSIDERATIONS
3 -3
9.
PULSE LOADING
3-40.
The power supply will automatically c r o s s over from constant voltage t o constant current operation, or the reverse, in respone t o an increase (over the preset l i m i t ) in t h e output current or voltage, respectively. Although the preset limit may be s e t higher than the average output current or voltage, high peak currents or voltages ( a s occur i n pulse loading) may exceed t h e preset limit and c a u s e crossover t o occur. To avoid this unwanted crossover, t h e preset l i m i t must be set for t h e peak requirement and not the average.
3 -4
1 . OUTPUT CAPACITANCE
3-42.
There are capacitors (internal) a c r o s s t h e output terminals of the power supply. These capacitors help t o supply high-current pulses of short duration during constant voltage operation. Any capacitance added externally will improve the pulse current capability, but will decrease the s a f e t y provided by t h e constant current circuit.
A high-current pulse may damage load components before t h e average output current is large enough t o c a u s e t h e constant current circuit t o operate.
3 - 4 3 .
The effects of the output capacitors during constant current operation a r e a s follows: a . The output impedance of t h e power supply d e c r e a s e s with increasing frequency. b. The r i s e t i m e of t h e output voltage is increased. c.
A large surge current causing a high power dissipation in the load occurs when t h e load impedance is reduced rapidly.
NEGATIVE VOLTAGE LOADING
3 - 4 5 .
A diode is connected a c r o s s t h e output terminals. Under normal operating conditions, t h e diode is reverse biased (anode connected t o negative terminal). If a negative voltage is applied t o t h e output terminals (positive voltage applied t o negative terminal), t h e diode will conduct, shunting current a c r o s s the output ter- minals and limiting the voltage t o t h e forward voltage drop of t h e diode. This diode protects the filter and output electrolytic capacitors.
I
3 -46. NEGATIVE CURRENT LOADING
3 - 4 7 .
Certain types of loads may c a u s e current t o flow into t h e power supply in the direction opposite t o the output current. If the reverse current exceeds
0
ampere, preloading will be necessary. For example; i f t h e load delivers
1 ampere t o the power supply with the power supply output voltage a t 18 vdc, a resistor equal t o
18 ohms (18v/la) should be connected across the output terminals. Thus, the
18 ohm resistor shunts the reverse current across the power supply. For more information on preloading, refer to paragraph C4 in the H-Lab Application Manual.
FIGURE 3-2. NORMAL STRAPPING PATTERN
I I
FIGURE 3-3. REMOTE SENSINO STRAPPINO PATTERN
FIGURE
3-4.
REMOTE RESISTANCE
PROGRAMMING(C0NSTANT VOLTAOE)
STRAPPING PATTERN
PROGRAMMING
RESISTOR
FIGURE 3-5. REMOTE VOLTAGE
PROGRAMMING (CONSTANT VOLTAGE)
STRAPPING PATTERN
'OURCE
PROGRAMMING
RESISTOR
FIGURE
3-6.
(CONSTANT CURRENT) STRAPPING PATTERN
SLAVE
+ + G A I
A 2 A3
A 4 - 3
-
+
+S A S
A 6 A 7
FIGURE 3 - 7 WORMAL PARALLEL STRAPPING PATTERN
MASTER
SLAVE
A.TWO POWER SUPPLIES
+ + m - -
A 1
AS A3 A 4 -S
-
+
+ S A 5 A 6 A 7
0.
THREE POWER SUPPLIES
FIGURE 3-8. AUTO- PARALLEL STRAPPING PATTERN
SLAVE
1
+ + a - -
A1 A 2 A 3 A 4 - S
-
+
+S
AS A 6 A7
MASTER
+ + G -
A1 A 2 A 3 A 4 - 9
-
+
+ S AS A6 A 7
+ + G A l A 2 A 3 A 4 - S
-
+
+ S A 5 A 6 A 7
FIGURE 3-9. NORMAL SERIES STRAPPING PATTERN
SLAVE
+ + a - -
A I A 2 A3 A 4
-S
-
+
+ S A 5 A 6 A 7
A. TWO POWER SUPPLIES
MASTER
+ + a - -
SLAVE I
MASTER
(MUST BE
MOST NEG-
ATIVE
)
+ + a - -
FIGURE AUTO-SERIES
STRAPPING
PATTERN
SLAVE
2
A1 A 2 A 3 A 4 - 9
8. THREE POWER SUPPLIES
-
+
+S
A 5 A 6 A 7
SLAVE
lelOlolelblalblol
MASTER
(MUST BE
MOST NEG-
A T lVE
+ + G -
A. TWO POWER SUPPLIES
A1 A 2 A 3 A 4 - S
-
+
+S A 5 A 0 A 7
S L A V E
I
FIGURE. 3-11 AUTO-TRACKING
STRAPPING
PATTERN
el-AVE 2
. .
. -
SECTION IV
PRINCIPLES OF OPERATION
4-1.
BLOCK DIAGRAM DESCRIPTION (See figure 4-1 .)
4 - 2 .
The main power transformer isolates the a c input from the power supply and reduces i t t o t h e voltage level required. Rectification and filteri,ng produces a smoothed d c output across the e d across the
- and
+ terminals.
A
large capacitor (Co) i s connect-
- and
+ terminals for low a c output impedance and t o help supply large pulse currents. An SCR regulator controls the a c input t o provide good regulation of the d c output. The auxiliary power transformer powers the SCR regulator control circuit and the bias and reference circuit which produces d c bias and reference voltages for the power supply.
4-3. The SCR regulator is controlled by the SCR regulator control circuit which operates i n response to signals developed by the voltage or current input circuit.
A gating circuit a s s u r e s that only one input circuit i s used a t a time.
4-4.
The voltage and current input circuits operate in a similar manner. Each circuit h a s a differential amplifier that amplifies a n error voltage that is proportion- a l t o the difference between
the
actual output and the programmed output. The programmed output is determined by the resistance of t h e programming resistors
(voltage and current controls). Each programming resistor h a s a constant current through i t which is maintained by the bias and reference circuit.
4 - 5 .
The voltage input circuit differential amplifier d e t e c t s the error voltage that is proportional t o the difference between the voltage across i t s programming resistors (R2-R8) and the d c output voltage. The error voltage is amplified and passed through the gating circuit t o the SCR regulator control which triggers the
SCR regulator. The SCR regulator increases or d e c r e a s e s the a c input voltage t o the main power transformer a s required to maintain a constant load voltage that is equal t o t h e programmed voltage. In constant voltage operation, the gating circuit i s biased t o inhibit the input from the current input circuit.
4-6.
The current input circuit differential amplifier d e t e c t s the error voltage that i s proportional t o the difference between t h e voltage across i t s programming resistors (R9-R10) and the voltage a c r o s s current monitoring resistor R23
.
The voltage across R23 is proportional t o t h e load current. The SCR regulator responds t o the amplified error voltage by increasing or decreasing the a c input current t o the main power transformers a s required t o maintain a constant load current. In constant current operation, t h e gating circuit i s biased t o inhibit the input from the voltage input Circuit.
4 - 7 .
To prevent overvoltage and excessive surge current when the power supply is turned-on, the turn-on circuit establishes initial conditions i n t h e gating circuit.
The turn-on circuit is activated by the bias and reference circuit when the power supply is turned-off.
4-8.
A voltmeter is connected across the
- and
+ terminals t o monitor the output voltage. An ammeter is connected across current monitoring resistor R23 t o monitor the output current (proportional t o voltage across R23).
4-9.
CIRCUIT DESCRIPTION (See figure 4-2 a t back of manual.)
4-10. AC INPUT
4-11. The 105-125 vac, 57-63 cps, single phase input is applied t o transformer
T2 and t o t h e s e r i e s combination of transformer T1 and SCR's CR17 and CR18 which are i n parallel opposition. The SCR's a r e used t o regulate t h e d c output by control- ling t h e average value of the a c input to transformer T I . Capacitors C11 and C12 smooth transients t o prevent t h e SCR's from being triggered by a rapidly changing voltage from anode to cathode. Resistor R21 damps oscillations that may occur due t o resonance of C12 and the leakage inductance of T I . The leakage inductance of
T 1 limits the peak input current.
4-12. DC OUTPUT
4-13
.
The output of the secondary of transformer T1 is full-wave rectified by bridge rectifier CR19 through CR22 and filtered by pi-section filter C13, C 1 7, and L1. Resistor R29 damps the parallel resonance of L1 and C17. The d c output is regulated t o a constant value by the SCR's i n t h e a c input line. Capacitor C17 is t h e output capacitor. Diode CR23 is connected across the filtered d c output t o protect t h e power supply from reverse voltage applied t o the output terminals.
Resistor R23 is the current monitoring resistor; t h e full load current flows through it.
Resistors R25 and R27 a r e used t o calibrate the voltmeter and ammeter, respectively.
4-14. VOLTAGE INPUT
4-15
.
GENERAL. The voltage input circuit is basically a differential amplifier
(Ql-Q2) that detects any voltage difference between the programmed output voltage and the actual output voltage. The differential amplifier output voltage varies in proportion t o the power supply output voltage valiation.
4 -16.
Q2 INPUT. Voltage divider R6-R47 maintains a slightly negative b a s e bias t o ensure that t h e output voltage can be programmed to zero. The output of 92 i s emitter-coupled (resistor R4) t o Q1.
4-17. Q1 INPUT. There a r e three inputs t o t h e b a s e of Q1; one determined by the programmed voltage (voltage controls ~ 2 - R 8 ) , the second determined by t h e collect- or voltage of Q1 (negative feedback), and the third is from t h e positive s i d e of the main rectifier. The collector current of Q1 is determined by the difference between i t s b a s e and emitter inputs. This difference i s a n error voltage that is proportion- a l t o t h e difference between t h e programmed output voltage and t h e actual output voltage. The negative feedback from collector t o b a s e (C4, and R17-R18 in parallel) improves the stability of the voltage-regulating feedback loop.
4-18.
The input from t h e positive s i d e of t h e main rectifier (C1 and R1) improves loop stability by making t h e differential amplifier insensitive to output voltage variations of four c p s or greater. Below four c p s t h i s input is negligible. This input is n e c e s s a r y b e c a u s e t h e phase shift of t h e pi-section output filter begins t o become e x c e s s i v e aver four c p s
.
Resistors R1 and R5 a r e arranged s o t h a t t h e four c p s input is isolated from t h e negative feedback input; and s o that n e c e s s a r y impedance l e v e l s a r e obtained looking out from t h e b a s e of Q1. The collector out- put of Q1 is coupled t o t h e gating circuit.
4-19. CLAMPING. In order t o protect t h e differential amplifier, t h e b a s e of Q1 is clamped with respect t o
-S by diodes CR1 and CR2 t o prevent e x c e s s i v e b a s e volt- a g e i n either direction. Diode CR1 clamps t h e b a s e t o approximately -0.7 vdc;
CR2 and t h e base-emitter junction of Q1 clamp t h e b a s e t o approximately +1.4 vdc.
Zener diode VRI clamps t h e programming terminals t o prevent a n e x c e s s i v e error signal t h a t would c a u s e e x c e s s i v e output voltage. This would occur, for example, if t h e programming terminals were opened accidentally. To prevent overshoot when the power supply s w i t c h e s from constant current t o constant voltage, diodes CR9 and CRlO clamp t h e collector of 91. Resistor R30 provides a small bleed current for CR1O
,
4-2 0. CURRENT INPUT
4-2 1. GENERAL. The current input circuit is basically a differential amplifier
(Q8-Q9) that d e t e c t s any current difference between t h e programmed output current
(proportional t o voltage a c r o s s current controls) and the a c t u a l output current (pro- portional t o voltage a c r o s s current monitoring r e s i s t o r R23). The differential amplifier output voltage v a r i e s in proportion t o t h e output current variation.
4-22. Q8-Q9 INPUT. The input t o t h e differential amplifier ( a c r o s s b a s e s of 98-
Q9) is t h e voltage difference a c r o s s current controls R9-R10 and current monitoring r e s i s t o r R23. Because t h e programming current is constant in constant current operation, t h e voltage input t o t h e differential amplifier varies a s t h e load current through R23 (error voltage). Capacitors C6 and C24 and r e s i s t o r R22 provide gain roll-off a t high frequencies. Diode CR26 clamps t h e voltage ( 0 . 7 vdc) a c r o s s t h e emitter-base junction of Q9 and R20.
his
clamping action prevents e x c e s s i v e r e v e r s e b a s e voltage i n Q9 when very large load current is drawn (output terminals shorted). To prevent overshoot when the power supply switches from constant voltage t o constant current opleration, diodes CRlO and CR12 clamp t h e collector of
Q8
4-23. Q8-Q9 OUTPUT. Resistor R13 is t h e collector load for
Q8.
The collector output of
Q8 i s coupled t o t h e gating c i r c u i t . Voltage divider R20-R46 b i a s e s t h e b a s e of Q9 and maintains a slightly negative b a s e b i a s t o ensure t h a t t h e output current c a n b e programmed t o zero. Resistor R44 provides positive feedback t o improve load regulation during constant current operation.
4-24. GATING CIRCUIT
4-25.
Transistor
Q4 draws current from t h e SCR control circuit (capacitor C25).
The magnitude of t h i s current is determined by either t h e voltage or current input circuit. For constant voltage operation, diode CR7 is forward biased t o permit t h e voltage input circuit t o drive
Q4;
diode CR8 is reverse biased t o inhibit t h e input from t h e current input circuit. For constant current operation, t h e reverse occurs.
4-26.
To prevent transients i n the d c output when t h e power supply is turned-on, t h e turn-on of
Q4
i s delayed by capacitor C2 which charges throuqh R12, R15 and
CR5. When C2 charges sufficiently t o reverse b i a s CR5, a l l t h e current through R15 flows t o t h e b a s e of
Q4 t o turn i t on. This b a s e current is controlled by t h e voltage or current input circuits via CR7 or CR8, respectively. For example, during constant voltage operation t h e collector voltage of Q1 (voltage input) forward b i a s e s CR17
(CR8 reverse biased by Q8), t h e current through CR7 will vary a s Q1 collector volt- a g e v a r i e s and thus vary
Q4 b a s e current; therefore, t h e collector current of
Q4 is controlled by t h e voltage input. In a similar manner, t h e current input circuit controls t h e collector current of Q4 during constant current operation.
4-2 7. TURN-ON CIRCUIT
4 -2 8 . Transistor Q3 provides a path for rapidly discharging C2 (in gating circuit) when t h e power supply is turned-off. This a s s u r e s t h a t C2 is discharged if t h e power supply is turned-on shortly after turn-off. The purpose of having C2 d i s - charged e a c h time t h e power supply is turned-on is t o maintain the same time delay i n t h e turn-on of t h e gating circuit (refer t o para. 4-26).
4-29.
SCR REGULATOR CONTROL (See waveshapes on figure 4-2 .)
4-30.
GENERAL. The SCR regulator control is b a s i c a l l y a blocking oscillator (Q7 and T3) that a p p l i e s p u l s e s t o t h e SCR regulator in r e s p o n s e t o error s i g n a l s d e t e c t - ed by t h e voltage or current input circuit. When transistor 9 7 conducts, t h e pulse developed i n winding 1-2 of transformer T3 is coupled t o t h e b a s e of Q7 (positive feedback) and t o t h e SCR regulator (CR17 and C ~ 1 8 ) . Capacitor C27 charges in op- position t o t h e feedback voltage and c u t s off Q7. The charge t i m e of C27 determines the pulse duration in t h e collector of Q7 (approximately 20 microseconds). The 35- vdc bias s u p p l i e s current through R52, CR46, and CR44 t o discharge C2 7 after Q7 s t o p s conducting.
4-3 1. GATE INPUT. Throughout t h e operation of t h e blocking oscillator, capacitor
C25 supplies most of t h e collector current for Q4 in the gating circuit (refer t o para. 4-25). The amount of current pulled from C25 by Q4 is determined by t h e in- put (from t h e voltage or current input circuit) t o t h e gating circuit. A s a result of t h i s current flow from C2
5, t h e voltage a c r o s s C25 i n c r e a s e s negatively with re- s p e c t t o t h e 6.0-vdc b i a s and h a s a waveshape that approximates a linear ramp.
Thus, t h e s l o p e of t h i s ramp is determined by the voltage or current input circuit.
Due t o t h e time d e l a y i n t h e feedback loop, t h e s l o p e of t h e ramp is constant for a half c y c l e of t h e a c input. The voltage on C25 is t h e emitter b i a s (forward b i a s when negative) for Q7 and therefore h e l p s determine the point a t which 9 7 conducts.
4-32. AC INPUT. The a c input t o transformer T2 is stepped-down and full-wave rectified by bridge rectifier CR39 through CR43. The output of t h e bridge rectifier is a negative-going pulsating d c (120 c p s ) . Voltage divider R50-R51 supplies a portion of this pulsating d c through C27 t o t h e b a s e of Q7; thus, t h e b a s e is reverse biased
.
4-33. FIRING.
A
point is reached during each c y c l e of t h e 120-cps pulsating d c
(each half c y c l e of t h e 60-cps a c input) when the reverse bias on t h e b a s e and t h e forward b i a s (capacitor C25) on t h e emitter of Q7 are equal, and therefore 9 7 has zero b i a s . A s t h e ramp voltage a c r o s s C25 g o e s more negative than t h e b a s e volt- age, t h e base-emitter junction of Q7 begins t o become forward biased. When t h e emitter is more negative than the b a s e by approximately
0.5 volts, 9 7 conducts.
The firing point of Q7 i s therefore determined by both t h e d c output error and the line voltage change. Because Q7 saturates when it conducts, t h e collector voltage approximates a rectangular wave with a negative going pulse width of approximately
20 microseconds (determined by C27 and R51). The conduction of 9 7 charges C25 in t h e positive direction (clamped by C ~ 4 9 ) . When Q7 stops conducting, t h e ramp a c r o s s C25 begins again. Kowever, Q7 is held cut-off by the charge on C2 7.
4-34. INITIAL CONDITIONS.
A t t h e beginning of each cycle of the 120-cps pulsat- ing dc, certain initial conditions must be established on capacitors C25 and C27.
When t h e negative-going pulsating d c is a t t h e end of its cycle (C27 negatively charged earlier in t h e cycle by t h e feedback voltage), CR44 and CR45 become forward biased and current flows from t h e 35-vdc b i a s through R52, CR46, and CR44 t o d i s - charge C27 t o approximately zero volts and through R52, CR46, and CR45 to charge
C25 t o approximately 0.7 volts (clamped by CR49). This discharge and charge occurs rapidly, s o that it i s completed before the next cycle begins and Q7 c a n con- duct again. Diode CR47 provides another path for the current through CR44 s o that t h e voltage t o which C27 discharges remains predictable.
A s t h e negative-going pulsating d c increases i n the next cycle, CR44 and CR45 become reverse biased.
4-35. BRIDGE RECTIFIER. At the zero cross-over region of t h e voltage waveform on secondary winding 3-4 of transformer T2, t h e voltage is insufficient t o forward bias t h e rectifiers in t h e bridge. In order t o maintain definition between t h e end of one cycle of t h e rectified output and t h e beginning of t h e next cycle, diode CR41 provides approximately 0.7 volts a t t h e rectified output. The current for CR4 1 is supplied through CR46.
A s t h e voltage a c r o s s t h e secondary winding moves away from t h e zero cross-over region, CR4
1 becomes reverse biased.
4 -36. TRANSIENTS, DECOUPLING AND PROTECTION. Transients in t h e pulsating d c a r e reduced by R56 and C2 8. The b a s e of 9 7 is decoupled by C3
.
The voltage spike in t h e collector of Q7, induced by secondary winding 1-2 of transformer T3 when
Q7 cuts-off, is clamped by CR48. The collector is decoupled by R53 and C26.
4 -3 7. SCR REGULATOR
4-3 8. GENERAL. The SCR regulator (CR17 and CR18) controls the a c input voltage and current t o main power transformer T 1 in response t o the voltage and current error signals. In constant voltage operation, t h e a c input voltage t o T1 is adjusted s o that the output voltage remains constant with changing loads. In constant current operation, t h e a c input current to T1 i s adjusted s o that t h e output current remains constant with changing loads and the output voltage i s allowed t o vary.
4-39. GATING. Each half cycle of the a c input, either CR17 or CR18 is forward biased. The pulse induced i n secondary windings 5-6 and 7-8 of T3 by the SCR control, turns on t h e SCR that i s forward biased when t h e pulse occurs. The other
SCR is not affected by t h e g a t e pulse because it is reverse biased.
A g a t e pulse occurs each half c y c l e of the a c input, unless the output is open. The timing of t h e gate pulse with respect t o t h e a c input is determined by t h e error in the d c out- put via t h e loop action.
4-40. AC INPUT CONTROL. When a n SCR is gated on, it conducts until its anode- to-cathode voltage goes t o approximately zero, Thus, t h e earlier a n SCR i s gated on, the greater the portion of t h e a c input that will be applied t o TI. Because of t h e leakage inductance-of TI, the conduction of a n SCR may extend into t h e next half cycle. The conduction period may be shortened a t high output by the voltage across capacitor C13 through C16 being reflected back into t h e primary. By con- trolling the a c input t o T1 each half cycle, t h e average value of the voltage or current a t the output of bridge rectifier CR19 through CR21 is adjusted s o that d c output voltage or current is maintained constant.
4-4 1. PROTECTION. Diodes CR50 and CR5 1 prevent anode induced reverse gate currents from being fed back to the control circuit. Resistors R54 and R55 limit current i n t h e SCR g a t e s .
4-42. BIAS AND REFERENCE CIRCUIT
4-43. GENERAL. The bias and reference circuit supplies three voltages ( t 3 5 ,
+6.0, and -19.5 vdc) for internal power supply operation, and maintains the pro- gramming currents constant. The t 3 5 vdc i s not regulated. The -19.5 vdc, t 6 . 0 vdc, and the. programming currents a r e regulated.
4-44. t 3 5 AND t 6 . 0 VDC. The output of secondary winding 5-6 of transformer T2 is full-wave rectified by CR30 and CR31. Capacitors C20 and C21 each charge t o t h e peak rectified voltage (voltage doubling). The t 6 . 0 vdc (with respect t o -S) is maintained by diodes CR6 and CR14 and by zener diode VR4. The +35 vdc includes includes t h e t 6 . 0 vdc and t h e voltage across C2
1.
The t 6 . 0 vdc and t h e negative voltage across C20 provide t h e unregulated input t o t h e -19.5 vdc regulator.
4-45. -19.5 VDC. For the -19.5 vdc, transistor 910 i s t h e error detector/ amplifier. Zener diode VR3 and diode CR27 provide a reference voltage a t the emitter of 910. Voltage divider R35-R36 supplies a n error voltage t o t h e b a s e of
Q10 which amplifies and applies it t o t h e base of s e r i e s regulator 911. The base drive of Q11 adjusts the voltage across Q11 a s required t o compensate for the error in t h e -19.5 vdc. Resistor R3 7 s e t s the optimum current through temperature-com- pensated Zener diode
V R 3 .
Resistor R45 improves t h e line regulation. Resistor
R56 reduces power dissipation in 011. Capacitor C22 stabilizes the loop.
4-46.
PROGRAMMING CURRENTS. Each prouramming current is held constant in a similar manner. The voltage across emitter resistors R38 and
R40 is held constant by VR3, CR27, and t h e base-emitter drop of each transistor. Thus, the emitter current in each transistor i s constant and therefore the collector currents are nearly constant. The collector currents of Q5 and
Q6
are the constant voltage and constant current programming currents, respectively. Resistors R39 and R41 are used for trimming. Resistors R42 and R43 a r e collector loads. Diode CR28 clamps t h e collector of
Q5 t o protect against excessive positive voltage (breakdown) which might occur i f the voltage controls a r e reduced t o zero rapidly (positive d c output voltage would appear a t collector).
Table 5-1. Test Equipment
.
Type
Required
Characteristics
U s e
Recommended
Model
Differential Voltmeter Sensitivity: 1 mv full s c a l e (min.)
Measure regulation HP 74 1A and d c voltages:
Input impedance: 10 calibrate meters m egohm s
(See note 1)
AC Voltmeter Accuracy: 2%
Sensitivity: 1 mv full s c a l e (min
.)
Measure a c voltages HP 403B and ripple
Variable Voltage
Transformer
r
Oscilloscope
Range: 90-130 volts Vary and measure
Equipped with voltmeter a c input voltage a c c u r a t e within 1 volt
-------
Battery
Switch
Resistor
Resistor
Resistor
Resistor
Capacitor
Oscillator
Sensitivity: 5mv/cm
(min .)
Differential input
Measure ripple and HP 130C transient r e s p o n s e
32 vdc
10 -ampere capacity
Measure transient r e s p o n s e
-------
Transient response;
Constant current load regulation;
.--
-------
3
.2 ohm, +5%, 320
.N
Load r e s i s t o r Rex Rheostat
(See note 2)
5 milliohms, 10 am- Current monitoring Any 50 mv, peres, 4 terminals
I W
ampere meter shunt
1, 000 ohms, +I%, 2 w Measure impedance non-inductive
-------
300 ohms, t 5 % , 10 w
Measure impedance
-------
500 pfd, 50 vdcw Measure impedance
-------
Range:
1 c p s t o 100 k c Measure impedance HP 202C
Accuracy: 2%
Output: 10 vrms
P
Table 5-1. Test Equipment (cont
.)
1
Type
Required
Characteristics
Controlled-temperature Range: 0 -5 O°C oven
Use
Measure tempera- ture stability
Recommended
M ode1
-------
*
Resistance box Range:
0 - 6,400 ohms
Measure program- H-Lab
693 1A
Accuracy:
0.1%
plus ming coefficients
1 ohm
Make-before-break contacts
NOTE 1
A
satisfactory substitute for a differential volt- meter is tb arrange a reference voltage source and null detector a s shown in figure 5-1. The reference voltage source i s adjusted s o that the voltage difference between the supply being measured and the reference voltage will have t h e required resolution for the measurement being made. The voltage difference will be a function of t h e null detector that is used. For measure- ments a t the b a s e of transistor
Q4,
a null detect- or with input impedance of 10 megohms or great- er is required. Otherwise, satisfactory null detectors are: HP 405AR digital voltmeter, d c voltmeter, HP 419A null detector, a d c coupled oscilloscope utilizing differential input, or a 50 mv meter movement with a 100 division scale.
A
2 mv change in voltage will result in a meter de- f lection of four divisions.
CAUTION
Care must be exercised when using a n electronic null detector in which one input terminal is ground- ed t o avoid ground loops and circulating currents.
NOTE 2
To obtain 3
- 2
output terminals, turn front-panel CURRENT con- trols fully clockwise (maximum), adjust front- panel VOLTAGE controls for 32 vdc and adjust rheostat until output current is
10
amperes.
+
-
- 9 - + + 9
F
POWER
SUPPLY
UNDER
TEST
LOAD
t t 0
Q @ @
NULL DETECTOR
FIQURE 5-1. DIFFERENTIAL VOLTMETER SUBSTITUTE, TEST SETUP
I
REFERENCE
VOLTAGE
SOURCE
+
Elo
-
3
3
.
SECTION V
MAINTENANCE
5-1. GENERAL
5-2. Table 5-1 lists t h e type of t e s t equipment, i t s required characteristics, its u s e , and a recommended model for performing t h e instructions given in t h i s section.
Upon receipt of t h e power supply, t h e performance check (para. 5-7) should be made. This check is s u i t a b l e for incoming inspection. Additional specification c h e c k s a r e given i n paragraphs 5-24 through 5-36. If a fault is detected i n t h e power supply while making t h e performance check or during normal operation, pro- c e e d t o t h e troubleshooting procedures (para. 5-39). After troubleshooting and re- pair (para. 5
-5 0)
, perform a n y n e c e s s a r y adjustments and calibrations (para. 5
-5
1).
Before returning t h e power supply t o normal operation, repeat t h e performance check t o ensure t h a t t h e fault h a s been properly corrected and that no other faults e x i s t .
Before doing any maintenance c h e c k s , turn-on power supply, allow a half-hour warm-up, and read t h e measurement techniques (para. 5-3).
5-3. MEASUREMENT TECHNIQUES
5-4. A measurement made a c r o s s t h e load includes t h e effect of t h e impedance of t h e l e a d s connecting t h e load; t h e s e l e a d s c a n h a v e a n impedance s e v e r a l orders of magnitude greater than the output impedance of t h e power supply. When measuring t h e output voltage of t h e power supply, u s e t h e -S and +S terminals.
5-5. For output current measurements, t h e current monitoring r e s i s t o r s h o u l d ' b e a four-terminal r e s i s t o r . The four terminals a r e connected a s shown i n figure 5-2.
TO UNGROUNDED
TERMINAL OF 4
POWER SUPPLY
EXTERNAL
CURRENT MONITORING TERMINALS
-
LOAD
TERMINALS
TO GROUNDED
TERMINALOF
POWER SUPPLY
Figure 5 - 2, Output Current Measurement Technique
5-6.
When using a n oscilloscope, ground o n e terminal of t h e power supply and ground t h e c a s e a t t h e s a m e ground point. Make c e r t a i n that t h e c a s e is not a l s o grounded by some other means (power line)
.
Connect both o s c i l l o s c o p e input l e a d s t o t h e power supply ground terminal and check that t h e o s c i l l o s c o p e is not exhibit- ing a ripple or transient d u e t o ground loops, pick-up, or other means.
5
-7.
PERFORMANCE CHECK
5-8. GENERAL
/
5-9. The performance check is made using a 115-volt, 60-cps, single-phase in- put power soufce. The performance check i s normally made a t a constant ambient room temperature, The temperature range specification c a n b e verified by doing the performance check a t a controlled temperature of OoC and a t a controlled tempera- ture of 50°c. If the correct result is not obtained for a particular check, d o not adjust any controls; proceed t o troubleshooting (para. 5 -39)
.
5-10. RATED OUTPUT AND METER ACCURACY
5
-
1 1.
CONSTANT VOLTAGE. Proceed a s follows
: a . Connect the 3.2-ohm load resistor across the output terminals and the differential voltmeter across t h e
-S
and
+S
terminals. b.
Turn front-panel CURRENT controls fully clockwise (maximum). c
.
Turn front-panel VOLTAGE controls until front-panel voltmeter indicates
32.0 vdc. d . The differential voltmeter should indicate
32.0
+_
0.64 vdc.
t
+
- c9
8
i
POWER
SUPPLY
UNDER
TEST
1
DIFFERENTIAL
VOLTMETER
@
741
+ - G
3 @ Q
LOAD
-
RESISTOR
m
-
3.2-
REX RHEOSTAT
SHORT1 NG
SWITCH
-
1 1 o
. O O S ~
JVVl
"
CURRENT MONITORING
RESISTOR
(
10 AMPERE METER SHUNT)
+
SHORTING SWITCH
USED ONLY FOR
CONSTANT CURRENT
LOAD REGULATION
CHECK.
FIGURE 5-3. CONSTANT CURRENT TEST-SETUP
5 -12. CONSTANT CURRENT. Proceed a s follows: a . Connect t e s t setup shown i n figure
5-3. b. Turn front-panel VOLTAGE controls fully clockwise (maximum). c
.
Turn front -panel CURRENT controls until front-panel ammeter indicates
10 amperes. d. The differential voltmeter should indicate 50
+
1. 0 mvdc.
- 5-13. LINE REGULATION
5 -14. CONSTANT VOLTAGE. Proceed a s follows : a . Connect the 3.2-ohm load resistor across the output terminals and the differential voltmeter across the
-S
and +S terminals. b
.
Turn front-panel CURRENT controls fully clockwise (maximum)
. c.
Connect the variable voltage transformer between the input power source and the power supply power input. Adjust the variable voltage transformer t o 105 vac
. d . Turn front-panel VOLTAGE controls until the differential voltmeter indi- c a t e s 32.0 vdc. e. Adjust the variable voltage transformer to 125 vac. f .
Differential voltmeter indication should change by l e s s than 10 mvdc.
5 -15. CONSTANT CURRENT. Proceed a s follows: a . Connect t e s t setup shown in figure 5-3. b. Turn front-panel VOLTAGE controls fully clockwise (maximum). c. Connect the variable voltage transformer between the input power source and the power supply power input. Adjust the variable voltage transformer to 105 vac
. d. Turn front-panel CURRENT controls until front-panel ammeter indicates
10 amperes. e
.
Record voltage indicated on differential voltmeter f. Adjust the variable voltage transformer t o 125 vac. g. Differential voltmeter indication should change by less than 0.5 mvdc.
5
-
16
.
LOAD REGULATION
5
-
1 7.
CONSTANT VOLTAGE. Proceed a s follows : a . Connect the 3.2-ohm load resistor across t h e output terminals and the differential voltmeter across the -S and
+S
terminals
. b. Turn front-panel CURRENT controls fully clockwise (maximum). c. Turn the front-panel VOLTAGE controls until front-panel ammeter indi- cates 10 amperes. d. Record voltage indicated on differential voltmeter. e. - Disconnect load resistor. f . Differential voltmeter indication should change by less than 20 mvdc.
5-18. CONSTANT CURRENT. Proceed a s follows: a . Connect t e s t setup shown in figure 5-3. b
.
Turn front-panel VOLTAGE controls fully clockwise (maximum)
. c. Turn front-panel CURRENT controls until front-panel ammerer indicates
10 amperes. d . Record voltage indicated on differential voltmeter. e . Close t h e shorting switch. f . Differential voltmeter indication should change by l e s s than 0.5 mvdc.
5-19. RIPPLE AND NOISE
5-20. Proceed a s follows: a . Connect the 3 .Z-ohm load resistor across t h e output terminals and the a c voltmeter across the
-S and t S terminals. b. Turn front-panel CURRENT controls fully clockwise (maximum). c. Connect the variable voltage transformer between the input power source and the power supply power input. Adjust the variable voltage transformer t o 125 vac
. d . Turn front-panel VOLTAGE controls until front-panel ammeter indicates
10 amperes. e. The a c voltmeter should indicate less than 32mvrms.
5
-2 1.
TRANSIENT RECOVERY TIME
5-22. Proceed a s follows: a . Connect test setup shown in figure 5 - 4 . b. Turn front-panel CURRENT controls fully clockwise (maximum). c . Turn front-panel
VOLTAGE
controls until front-panel ammeter indicates d . Open and c l o s e the switch several times and observe the oscilloscope display. e . Oscilloscope display should be a s shown in figure 5 - 5 .
-
OSClLLOSCOPE
@
l30C
3 2 V D C
31!1:
I
W T E : OSCILLOSCOPE
YUST
BE D C COUPLED. b
UNDER
TEST
J
6.Y n
CIOURE 5-4 T R A W E N T RECOVERY T I M E , TEST S E T W
3 0 0 MSEC
HALF LOAD
-
FULL LOAD
5-23. ADDITIONAL SPECIFICATION CHECK
5-24.
TEMPERATURE COEFFICIENT
5 -2.5
.
CONSTANT VOLTAGE. Proceed a s follows: a . Connect the 3.2 -ohm load resistor a c r o s s the output terminals and the differential voltmeter a c r o s s the -S and +S terminals.
b.
Turn front-panel CURRENT controls fully clockwise (maximum)
. c
.
Turn front-panel VOLTAGE controls until t h e differential voltnleter indi- c a t e s 32
V ~ C . d
.
Insert t h e power supply into the controlled-temperature oven (differen-
. tial voltmeter and load remain outside oven). Set the temperature to 30°c and allow a half -hour warm-up. e
.
Record the differential voltmeter indication.
f .
Raise t h e temperature to 40°C and allow a half-hour warm-up. g. Differential voltmeter indication should change
by
l e s s than 240 mvdc from indication recorded in s t e p e.
5
-2
6 . CONSTANT
CURRENT.
Proceed a s follows : a . Connect t e s t setup shown in figure 5-3.
b.
Turn front-panel VOLTAGE controls fully clockwise (maximum). c. Turn front-panel CURRENT controls until the differential voltmeter indi- c a t e s 50 mvdc. d . Insert t h e power supply into the controlled-temperature oven (differen- tial voltmeter and load remain outside oven). Set the temperature t o 30°c and allow a half -hour warm-up. e. Record t h e differential voltmeter indication.
f . Raise the temperature to 40°C and allow a half-hour warm-up. g
.
Differential voltmeter indication should change
by
l e s s than
1 . 5 mvde from indication recorded in s t e p e.
5 -2 7. OUTPUT STABILITY
5-2 8. CONSTANT VOLTAGE. Proceed a s follows:
a . Connect t h e 3.2-ohm load resistor across the output terminals and t h e differential voltmeter across t h e -S and +S terminals. b.
Turn front-panel CURRENT controls fully clockwise (maximum). c . Turn front-panel VOLTAGE controls until the differential voltmeter indi- c a t e s 32 vdc. d . allow a half-hour warm-up and then record t h e differential voltmeter in- dication. e. After eight hours, the differential voltmeter indication should change by l e s s than 72 mvdc from indication recorded in s t e p d .
5 -29. CONSTANT CURRENT. Proceed a s follows: a . Connect t e s t setup shown in figure 5-3. b. Turn front-panel VOLTAGE controls fully clockwise (maximum). c. Turn front-panel CURRENT controls until the differential voltmeter indi- c a t e s 50 mvdc. d . Allow a half-hour warm-up and then record t h e differential voltmeter indication. e. After eight hours, t h e differential voltmeter indication should change by less than
0.5 mvdc.
5 -30. REMOTE PROGRAMMING
5 -3 1
.
CONSTANT VOLTAGE. Proceed a s follows: a . Turn-off power supply and arrange rear terminal strapping pattern for constant voltage remote programming a s shown in figure 3-4; u s e the resistance box ( s e t t o 2,000 ohms) for the remote programming resistance. (Refer t o para. 3-17 b.
Connect t h e 3.2-ohm load resistor across t h e output terminals and t h e differential voltmeter across the
-S
and +S terminals. c
.
Turn front-panel CURRENT controls fully clockwise (maximum)
. d . Turn-on power supply, allow a half-hour warm-up and then record the differential voltmeter indication. e. Increase t h e remote programming r e s i s t a n c e i n 200-ohm s t e p s t o 3,000 ohms; record t h e differential voltmeter indication a t each step. The voltage indi- cation should increase 1.0 i O . O 1 vdc tit each step.
f .
Set the remote programming resistance t o 5,400 ohms and repeat s t e p e until t h e remote programming resistance reaches 6,400 ohms.
g.
Turn-off power supply and reconnect normal strapping pattern (figure 3-2).
5 -3 2 . CONSTANT CURRENT. Proceed a s follows: a . Turn-off power supply and arrange rear terminal strapping pattern for constant current remote resistance programming a s shown in figure 3-6: u s e t h e resistance box ( s e t t o 75 ohms) for t h e remote programming resistance. (Refer t o para. 3-18 and 3-23 through 3-25 .) b. Connect t e s t setup shown in figure 5-3. c. Turn front-panel VOLTAGE controls fully clockwise (maximum). d.
Turn-on power supply, allow a half-hour warm-up and then record t h e differential voltmeter indication. e. Increase the remote programming resistance in 25-ohm s t e p s t d
125
ohms; record the differential voltmeter indication a t each s t e p . The voltage indication should increase
5.D
_+
0.5 mvdc, a t each step. f. Set the remote programming resistance t o 200 ohms and repeat s t e p e until t h e remote programming resistance reaches 250 ohms. g . Turn-off power supply and reconnect normal strapping pattern (figure 3-2).
5 -3
3 .
OUTPUT IMPEDANCE
5 -34. Proceed a s follows: a . Connect test s e t u p shown i n figure 5 -6
. b. Turn front-panel CURRENT controls fully c l o c k w i s e (maximum).
16 vdc. c
.
Turn front-panel VOLTAGE controls until front -panel voltmeter indicates d . Adjust t h e o s c i l l a t o r for a 10-vrms (Ein), 0.5-cps output. e. Calculate and record t h e output impedance using t h e following formula:
R = 1 , 0 0 0 ohms; Eo measured a c r o s s power supply
-S
and
+S
terminals using a c voltmeter; Ein measured a c r o s s o s c i l l a t o r output terminals using t h e a c voltmeter. f . Using t h e formula given i n s t e p e , c a l c u l a t e and record t h e output imped- a n c e for oscillator frequencies of 100 cps,
1
kc, and 100 k c . g . The output impedance calculated and recorded in s t e p s e and f should f a l l i n t o t h e following ranges:
(1) d c t o 0.5 c p s ; less than 0.01 ohm
(2) 0.5 c p s t o 100 c p s ; less than 0.5 ohm
(3)
100 c p s t o
1 kc; less than 0.2 ohm
(4) 1 k c t o 100 kc; less than 1.0 ohm
5 -3 5 . OUTPUT TNDUCTANCE
5-36. Proceed a s follows: a . Repeat s t e p s a through c of para. 5-34. b. Adjust t h e o s c i l l a t o r for a 10-vrms (Ein), 10-kc output. c. Calculate and record t h e output inductance using t h e following formula:
Xi is tHe output impedance (Zout) calculated in s t e p s e and f of paragraph 5-34: f i s the frequency of t h e oscillator (determines which Zout i s used)
.
NOTE
The equation assumes tha X1 x1
= zout
d .
Using t h e formula given i n s t e p c, calculate and record the output induc- tance for oscillator frequencies of 50 kc and 100 k c a t 10 vrms. e. The output inductance calculated in steps c and d should not exceed
1 . 0 microhenry.
5-3 7. COVER REMOVAL
5 -3 8. The top and bottom covers a r e removed by removing both s e t s of s i x attaching screws.
5 -3
9 .
TROUBLESHOOTING
5-40. GENERAL
5 -4 1. If a fault in the power supply is suspected, remove the covers (para. 5 -38) and visually inspect for broken connections, burned components, etc. If the fault is not detected visually, proceed t o trouble analysis (para.
5-42). If the fault is, detected visually or via trouble analysis, correct it and then d o the performance check (para. 5-7). If a part is replaced, refer to repair and replacement (para 5-50) and t o adjustments and calibrations (para.
5-5 1)
.
5 -42. TROUBLE ANALYSIS
5 -43. GENERAL. Before attempting trouble analysis, a good understanding of the principles of operation should be acquired by reading Section IV of this manual.
Once the principles of operation a r e understood, logical application of this know- ledge i n conjunction with significant waveforms (on figure 4-2) and with normal voltage information (table 5-2) should suffice t o isolate a fault t o a part or small group of parts. As additional aids, t h e following a r e given:
5-45 .) Trouble i n t h i s circuit could show up in many ways because it supplies internal operating voltages for t h e power supply and t h e programming currents. b. Procedures for checking the voltage feedback loop for the two most common troubles: high or low output voltage (para
.
5 -46 or 5 -47, respectively)
. c.
Paragraph 5-48 which d i s c u s s e s common troubles.
5 -44. A defective. part should be replaced (refer to .the parts list in Section
VI)
.
Test points called out in the procedures are identified on the schematic diagram
(figure 4-2)
.
5-45.
BIAS
AND REFERENCE CIRCUIT. Proceed a s follows: a. Make a n ohmmeter check to be certain that neither the positive nor negative terminal is grounded. b. T u n frontdpanel VOLTAGE and CURRENT controls fully clockwise
(maximum). c.
Turn-on power supply (no load connected). d. Using t h e a c voltmeter, check voltage across secondary winding 5-6 of transformer T 2 . If voltage indication is not 23 k1.5 vrms, transformer T2 may be defective
. e.
Using the differential voltmeter, proceed a s instructed in table 5-3.
5 -46
.
HIGH
OUTPUT VOLTAGE. Proceed a s follows: a . Turn front-panel CURRENT controls fully clockwise (maximum). b.
Turn
front-panel VOLTAGE controls t o mid-position. c. Turn-on power supply (no load connected). d. Using the a c voltmeter, check voltage across t e s t points ACC and 45.
If voltage indication i s less than 1.0 vdc, CR17 or CR18 may be shorted. e. Using the differential voltmeter, check voltage across test points 33 and
36. If voltage is not
0.8 a0.12 vdc, check T2, CR39 through CR43, R50, and RS 1 . f . Using the differential voltmeter, proceed a s instructed In table 5-4.
5-4 7. LOW OUTPUT VOLTAGE. Proceed a s follows: a . Turn front-panel CURRENT controls fully clockwise (maximum)
. b. Disconnect anode or cathode of diode CR8.
c.
Turn-on power supply (no load connected). d. Turn front-panel VOLTAGE controls clockwise and observe the front- panel voltmeter to s e e if the 32vdc output can be obtained. If i t can, the probable cause of the low output voltage is one or more of the following:
(1) CR8 shorted.
(2)
Q8
shorted.
(5) R40, R43 open. e
.
If the 32vdc output cannot be obtained in step d, reconnect diode CR8 and turn t h e front-panel VOLTAGE controls t o mid-position. f .
Using the oscilloscope, check t h e following:
(1) Waveform across t e s t points 3 1
(positive 1ead)and 33 (waveform on figure 4-2). If peak negative voltage is less than 15 volts,
97,
R53, CR48, C25,
C26, or transformer T3 may be defective.
(2) Ripple waveform across t e s t points 18 (positive lead) and 48 (wave- form shown on figure 4-2)
.
If waveform is correct (except for amplitude), proceed t o s t e p (3). If wavefom is incorrect, proceed a s follows:
(a) If the ripple waveform is half-wave (60 cps) instead of full-wave
(120 cps), either SCR (CR17 or CR18) may be open or t h e applicable gate circuit for t h e SCR may be defective. To check the g a t e circuit, disconnect R54 or R55 ( a s applicable) and make a n ohmmeter check from the open end of the resistor t o t e s t point ACC or 45 ( a s applicable). If the resistance is greater than 55 ohms, t h e gate circuit is defective
.
(b) If the ripple waveform indicates that neither SCR h a s fired, CR17 or CR18 may be shorted.
(c) If there or
T 1 may be defective. is no ripple waveform, both CR17 and CR18 may be open g. Using t h e differential voltmeter, proceed as instructed i n table 5-5.
5-48. COMMON TROUBLES. Table 5-6 gives t h e symptoms, checks, and probable c a u s e s for common troubles. The checks should be made using a 115-volt, 60-cps, single-phase power input and the t e s t equipment listed in table 5-1.
5 -49. REPAIR AND REPLACEMENT
5-50. Before servicing etched circuit boards, refer to figure 5-7. After replacing a semiconductor device, refer t o table 5-7 for checks and adjustments that may be necessary. If a check indicates a trouble, refer t o paragraph 5-39. If a n adjust- ment is necessary, refer t o paragraph 5-51.
S E R V I C I N G ETCHED CIRCUIT B O A R D S
Excessive heat o r pressure can lift the copper s t r i p from the board. Avoid damage by using a low power soldering iron (50 watts maximum) and following these instructions. Copper that lifts off the board should be cemented in place with a quick drying acetate base cement having good electrical insulating properties.
A break in the copper should be repaired by soldering a short length of tinned copper wire a c r o s s the break.
Use only high quality rosin c o r e solder when repairing etched circuit boards. NEVER USE PASTE FLUX.
After soldering, clean off any excess flux and coat the repaired a r e a with a high quality electrical varnish o r lacquer.
When replacing components with multiple mounting pins such a s tube sockets, electrolytic capacitors, and potentiometers, it will be necessary to lift each pin slightly, working around the components several times until i t is free.
WARNING: If the specific instructions outlined in the steps below regarding etched circuit boards without eyelets a r e not followed, extensive damage to the etched circuit board will result.
1. Apply heat sparingly to lead of component to be replaced. If lead of component passes through an eyelet in the circuit board, apply heat on com- ponent side of board. If lead of component does
- ductor side of board.
2. Reheat solder in vacant eyelet and quickly in- s e r t a small awl to clean inside ofhole. If hole does not have an eyelet, insert awl o r a
#57 drill from conductor side of board.
CONDUCTOR
4.
Hold part against board (avoid overheating) and solder leads. Apply heat to component leads on
3. Bend clean tinned leads on new part and care- fully insert through eyelets o r holes in board.
pJJ-.,
-c-=-=aw
In the event that either the circuit board h a s been damaged or the conventional method is impractical, use method shown below. This is especially applicable f o r circuit boards without eyelets.
1. Clip lead a s shown below.
2.
Bend protruding leads upward. Bend lead of new component around protruding lead. Apply solder using a pair of long nose pliers a s a heat sink.
C L I P
HERE
APPLY
SOLDER
This procedure i s used in the field only a s an alternate means of repair. It is not used within the factory.
Figure
5-
7 .
Servicing Etched Circuit Boards
5-13
5 -5 1. ADWSTMENTS AND CALIBRATIONS
5 -5
2 .
GENERAL
5-53
.
Adjustments and calibrations may be required after performance testing
(para. 5
-7),
additional specification testing (para. 5-23), troubleshooting (para.
5-39), or repair and replacement (para. 5 -50)
.
'Test points called out in the procedures a r e identified on t h e schematic diagram (figure 4-2). If a n adjustment or calibration cannot be performed, troubleshooting is required. Table 5-8 sum- marizes t h e adjustments and calibrations. The adjustments and calibrations are performed using a 115 -volt, 60-cps, single-phase power input t o the power supply.
5-54. METER ZERO
5-55. Proceed a s follows: charge. a . Turn-off power supply and allow 2 minutes for a l l capacitors t o dis- b. Rotate voltmeter zero-set screw (figure 3-1) clockwise until the meter pointer is t o t h e right of zero and moving to t h e left towards zero. Stop when point- er is on zero. If t h e pointer overshoots zero, continue rotating clockwise and re- peat this step.
c.
When t h e pointer is exactly on zero, rotate the zero-set screw counter- clockwise approximately 15 degrees t o free t h e screw from t h e meter suspension.
If pointer moves, repeat s t e p s a through c. d . Repeat s t e p s a through c for the ammeter.
5 -5 6. VOLTMETER TRACKING
5-5 7. Proceed a s follows: a . Connect t h e differential voltmeter across the -S and +S terminals. b. Turn front-panel VOLTAGE controls until the differential voltmeter indi- c a t e s 32 vdc. c.
Adjust R25 until the front-panel voltmeter indicates 32 vdc.
5 -5 8. AMMETER TRACKING
5-59. Proceed a s follows: a . Connect t e s t setup shown in figure 5 -3. b. Turn front-panel VOLTAGE controls fully clockwise (maximum)
.
c . Turn front-panel CURRENT controls until tho differential voltmeter indi- c a t e s 50 mvdc. d m Adjust R27 until t h e front-panel ammeter indicates
10
amperes.
5-60. CONSTANT VOLTAGE PROGRAMMING CURRENT
5-61. Proceed a s follows: a . Connect a 6,400-ohm, 0,1%, 1/2 w resistor between terminals
+S and
A6 on t h e rear terminal strip o£ t h e power supply. b.
Disconnect t h e jumper between terminals A6 and
A7.
c
.
Connect t h e r e s i s t a n c e box in place of R39 (shunt),
d .
Connect t h e differential voltmeter between t h e +S and
-S
terminals. e.
Adjust the r e s i s t a n c e box until t h e differential voltmeter indicates 32
*0.16 vdc, f . Choose resistor R39 (shunt) equal t o the r e s i s t a n c e required in s t e p e.
5-62. ZERO VOLTAGE OUTPUT
5-63. Proceed a s follows: a . Connect a jumper between the +S and A7 terminals on t h e rear terminal strip of t h e power supply. b
.
Connect t h e differential voltmeter between the
+S
and
-S terminals. c. Connect t h e resistance box in place of R6. d m Adjust t h e resistance box s o that t h e voltage indicated by t h e differen- t i a l voltmeter is between zero and
*10
mvdc. e . Choose resistor R6 equal t o t h e resistance value required in s t e p d .
5
-64, CONSTANT CURRENT PROGRAMMING CURRENT
5-65. Proceed a s follows: a . Connect t e s t setup shown in figure. 5-3. b. Connect a 250 -ohm,
0.1%,
1/2w resistor between terminals A2 and A3 on t h e rear terminal strip of t h e power supply. c. Disconnect t h e jumper between terminals A1 and A2.
d
.
Connect the resistance box i n place of R4 1 (shunt)
4
e. Adjust the resistance box until the differential voltmeter indicates 50
5.0mvdc. step e. f . Choose resistor R41 (shunt) equal t o the resistance value required in
5 -66. ZERO CURRENT OUTPUT
5-67. Proceed a s follows: a . Connect t e s t setup shown in figure 5-3. b. Connect a jumper between the A 1 and A3 terminals on the rear terminal strip of the power supply. c . Connect the resistance box in place of R20. d . Adjust the resistance box until the voltage indicated by the differential voltmeter is between zero and 0.1 mvdc
. e . Choose resistor R20 equal to the resistance value required in s t e p d.
NOTE
If the resistance value required is l e s s than
7,000 ohms or greater than 17, 000 ohms, change
R46. Replace the original R 2 0 .
5-68.
BIAS
AND REFERENCE LINE REGULATION
5-69. Proceed a s follows: a . Connect the variable voltage transformer between t h e input power source and the power supply power input. Adjust the variable voltage transformer to 105 vac
. b. Connect the differential voltmeter between t h e
+S and
-S terminals. c . Connect the resistance box in place of R45. d .
Turn front-panel VOLTAGE controls until the differential voltmeter indi- cates 32 vdc. e . Adjust the variable voltage transformer to 125 vac.
f . Adjust the resistance box until t h e voltage indicated by the differential voltmeter is within
18
mvdc of g. Choose resistor R45 equal t o the resistance value required i n step f .
NOTE
If the resistance value required is less than
2
ohms, troubleshooting is required. Replace t h e original
R45.
5
LINE IMBALANCE
5-71.
Proceed a s follows: a . Connect t h e
3
..2:
-ohm load resistor across the output terminals. b. Turn front-panel CURRENT controls fully clockwise (maximum). c
.
Connect t h e variable voltage transformer between the input power source and t h e power supply power input. Adjust the variable voltage transformer to
125
vac. d
.
Turn front-panel VOLTAGE controls until front-panel ammeter indicates
10 amperes. sync. e.
Connect t h e oscilloscope across t e s t points
18
and
48.
Use internal f .
Connect t h e resistance box in place of R17. g . Adjust t h e resistance box until the oscilloscope display i s similar t o the waveform for t e s t points
18-48
shown on figure
4-2.
h. Choose resistor R17 equal t o t h e resistance value required in step f
.
NOTE
If t h e resistance value required is less than 5,000 ohms, troubleshooting is required. Replace t h e original
R17.
1
5-72. CONSTANT CURRENT LOAD REGULATION
5-73. Proceed a s follows: a . Perform s t e p s a through e of para. 5-18. b. Place a 10-megohm resistor in place of
R44.
c.
Adjust the variable voltage transformer t o 125 vac. d . C l o s e t h e shorting switch. e . Differential voltmeter indication should change by l e s s than 0 , s mvdc.
If voltage change is greater than 0. 5 mvdc, reduce t h e 10-megohm resistor t o 9 megohms, set the variable voltage transformer t o 105 vac, open t h e shorting switch, record t h e differential voltmeter indication, and repeat s t e p s c and d
.
Repeat this process, reducing t h e 10-megohm resistor i n 1-megohm s t e p s until the voltmeter change is l e s s than
0.5 mvdc. Changes smaller than l-megohm may be required t o obtain the optimum resistance value for
R44.
Choose resistor
R44
equal t o the optimum resistance value required.
NOTE
If the resistance value required is l e s s than
1 megohm, troubleshooting is required. Re- place the original
R44.
From (+) t o
(-1
-S
33
33
40
2 4
2 2
21
2 3
20
39
5 1
-S
10
19
15
33
33
26
-S
18
14
-S
40
33
41
28
33
32
36
4 2
3 3
38
8
-S
-
S
19
16
2 2
21
38
2
7
12
2 7
2 5
48
19
A6
5 1
27
-S
33
5 1
5 1
5 1
Table 5-2. Normal Voltage
t
Voltage
19.5 +1.0 vdc
3 4 . 1 +1.7 vdc
6 . 0 +0.3 vdc
33.0 4 1 . 7 vdc
10.3 40.6 vdc
9 . 7 +0.5 vdc
9 . 7 +0.5 vdc
7 . 1 4 0 . 7 vdc
3 . 1 40.3 vdc
0.81 4 0 . 1 vdc
6.6 1 2 . 0 vdc
3.7 a 0 . 6 vdc
0.59 + O . l vdc
10.0 40.5 vdc
33,. 520.5vdc
0.72
i 0 . 1
v d c
0.04 + O . l v d c
0.45 40.07 vdc
0.06 h 0 . 1 vdc
0.82 4 0 . 1 vdc
1.14 *0.2 vdc
1.0 iO.5 v d c
7.0 + l . l vdc
0.8 +0.1 v d c
46 . O 42.3 vpp
66.0 42.3 vpp
14 .O +1.4 vdc
Typical
Peak-to-Peak Values
0.05 v
1.0 v
0 . 1 v
0.6 v
---
---
---
---
---
---
1.0 v
---
---
---
1.5 v
---
---
---
---
---
---
---
---
---
---
---
These measurements were made with a 115-volt,
60-cps, single-phase power input; t h e front-panel
CURRENT
controls fully c l o c k w i s e (maximum); t h e front-panel VOLTAGE controls s e t for 32 vdc out- put terminals ( loamperes)
.
Differential voltmeter
HP 741A w a s u s e d for a l l measurements.
Step
1
4
5
6
7
2
3
Table 5-3. Bias and Reference Circuit Troubleshooting
Meter
Common
Meter
Positive
Normal
Indication
If Indication i s not Normal,
Check t h e Following Parts
33
-
S
27
40
3 3
3 3
33 +1.7 vdc
6.2 *0.3 vdc
34.1
a1.7
vdc
CR31, C21
CR6, CR14, VR4
CR30, C20
5 1
5 1
5 1
5 1
-S
24
22
21
19.5 41 .0 vdc
10.3 40.6 vdc
9 . 7 40.5 vdc
9 . 7 +0.5 vdc
910, 911
CR27, VR3
R40, R43,
Q6
R38, R42, Q5
*
Step
1
Meter
Common
Table 5-4. High Output Voltage Troubleshooting
Meter
Positive Response
Probable C a u s e
E m i t t e r o f Q 4 29
<0.5 vdc a . Q4 shorted b. R16 shorted c .
R15 shorted
2
3
14
14
17
33 <2 vdc
CR7 open a . Q1 open b. Q2 shorted c. CR1 shorted d
.
R2-R8 open
I i
Step
1
2
3
Table 5 -5. Low Output Voltage Troubleshooting
Meter
Common
Emitter of
Q4
Meter
Positive
29
14
14
17
33
Response
> 5 vdc
40.4 vdc
>6 vdc
Probable C a u s e a .
Q4 open b. R16 open c. R15 open
CR7 shorted a . Q1 shorted b. Q2 open c. ~ 2 - R 8
1
1
Table 5-6. Common Troubles
1
Symptom
Fuse blows when power supply is turned on.
Poor line regulation
(constant voltage)
Poor load regulation
(constant voltage)
Poor line and load regulation (constant current)
'
High ripple
Poor stability
(constant voltage)
Poor stability
(constant cument)
Checks and Probable Causes
Power supply h a s internal short. Disconnect Collector of
Q7, turn-on power supply and check voltages (refer t o table 5 -2 or figure 4-2)
.
If f u s e blows with Q7 disconnect- ed, check CR17, CR18, and T3. a . Check bias and reference circuit (para. 5-45). b
Refer to paragraph 5-69 for adjustment.
.
Check line input to SCR regulator control circuit (T2,
CR39 through CR43, R50, R51). a . Check bias and reference circuit (para. 5 -45)
. b. Power supply going into current limit. Check constant c current input circuit.
.
Constant voltage loop oscillates. Check adjustment of R17 (para. 5-71). a . Check bias and reference circuit (para. 5-45). Refer to paragraph 5 -69 for adjustment. b. Power supply going into voltage limit. Check constant voltage input circuit. c. Constant current loop oscillates. Check adjustment of R44 (para. 5 -73)
. a . Check operating setup for ground loops. b. If output i s floating (ungrounded) connect 1-pf capaci- tor between output and ground (unless particular application prohibits this). c.
Check pi-section output filter C13, C17, and
Ll.
d . Line imbalance. Check adjustment of R17 (para. 5-70). a . Check bias and reference circuit line regulation .(Refer b
. t o para. 5 -69)
.
Noisy piogramming resistors ( ~ 2 - ~ 8 ) . c.
CR1 or CR2 leaky. d . R1, R5, R40, R41, o r R 4 3 n o i s y o r d r i f t i n g . e . Q1 or 9 2 defective. a . Check bias and reference circuit line regulation.
(Refer to para
.
5 -69)
. b
.
Noisy programming resistors (R9-R10)
. c . R20, R23, R38, R39, or R42 noisy or drifting. d .
Q8 defective.
A
t
Symptom
Oscillates
(constant voltage)
Oscillates
(constant. current)
i
Output voltage does not go t o zero.
Output current does
i-
not go t o zero.
Table 5-6. Common Troubles (cont .)
Checks and Probable Causes
Check R18, C1, C4, and adjustment of R17 (para. 5-71).
Check C6, C24, R22, and adjustment or R20 (para. 5-66) and adjustment of R44 (para. 5-72).
Check R6 and R47. (Refer t o para. 5-63
Check R20 and R46
.)
.
(Refer t o para. 5-6
7 .)
Table
5-7.
Checks and Adjustments after Replacement of Semiconductor Devices
Function
Gating Circuit
Check Adjust
Constant voltage differential amplifier
Constant voltage line and load regulation; transient recovery time; zero voltage output
R6,
R17
Turn-on circuit Excessive transients a t turn-on
-----
Constant voltage/constant current line and load regula
b
Constant voltage program-
1 ~ 3
1 ming coefficient
Constant voltage programming current regulator
Constant Current programming current regulator
SCR regulator control
Constant current program
- ming coefficient
Wavef o m s (shown in figure
R5 1
Constant current differential amplifier
Constant current line and load regulation: zero current output
Bias and reference error d etector/amplif ier
Bias and reference circuit line regulation
Bias and reference series regulator
Bias and reference circuit line regulation
Constant voltage protection Constant voltage load regulation
Forward bias regulators
Voltage across each diode
(0.6
t o
0.85
vdc)
R45
R45
-----
-----
Table 5-7. Checks and Adjustments after Replacement of Semiconductor Devices
(cont
.)
Circuit
Reference
CR17, CR18
CR19, CR20
CR2 1, CR22
CR23
CR2
6
Function
SCR regulator
Bridge rectifier
Output Protection
Constant current protection
Check
Constant voltage load regulation
Voltage across bridge a t full output (32 vdc)
Output voltage
Constant current line and load regulation
Rectifier output
(6
7 vdc)
Voltage across bridge
(20-25 peak, full wave)
CR30, CR3 1
Full-wave rectifier
CR39, CR40
CR41, CR42
CR43
Bridgerectifier
CR5, CR7,
CR8, CR44,
CR45, CR47,
CR48, CR49,
CR50, CR5 1,
Diode switches
VR1
Constant voltage program- ming protection
-----
VR3
A
VR4
Voltage reference
Voltage reference
Adjust
-----
-----
-----
-----
-----
-----
-----
Full output voltage and zero output voltage obtainable
---.-- via VOLTAGE controls: volt- a g e regulation a t 32 vdc output
Bias and reference circuit line regulation
R45
6.0 vdc line regulation
-----
Table 5-8. Adjustment and Calibration Summary
Adjustment or Calibration
Meter Zero
Voltmeter Tracking
Ammeter Tracking
Constant Voltage Programming Current
Zero Voltage Output
Constant Current Programming Current
Zero Current Output
Bias and Reference Line Regulation
Line Imbalance
w
Constant Current Load Regulation
Paragraph
Reference
5 -55
5-57
5 -59
5-61
5-63
5-65
5
-6 7
5 -69
5-71
5-73
Control Device
Meter Spring
R2 5
R2
7
R3 9
R6
R4 1
R2 0
R4 5
R17
R44
SECTION
VI
RE PLACEABLE PARTS
6- 1 INTRODUCTION
6-2 This s e c t i o n contains information for ord.ering replacement parts.
6-3 Table 6- 1 l i s t s parts in the alpha-numerical order of the circuit designators and provides t h e following information:
,
.
A.
Description (See l i s t of abbreviations below).
B.
C
Total quantity used i n t h e instrument.
.
Manufacturer's part number.
D. Manufacturer.
E. The Manufacturer's c o d e number a s l i s t e d i n the Federal Supply Code for Manufacturers H4- 1.
F. The H-P Part Number.
G
.
The recommended s p a r e parts quantity for complete maintenance during o n e year of isolated service. (Column A).
6-4 ORDERINGINFORMATION
6-5
To order replacement parts, a d d r e s s order or inquiry either t o your authorized
Harrison Laboratories s a l e s representative or t o Customer Service, Harrison Laboratories,
100 Locust Avenue, Berkeley Heights, New Jersey.
6 - 6
Specify t h e following information for e a c h part:
A.
B
Model and complete s e r i a l number of instrument.
.
Circuit reference designator.
C . Description.
A
B
C
6-7 To order a part not l i s t e d i n Table 6-1, g i v e a complete description of t h e part and include its function and location.
Reference Desiqnators
=
=
= assembly motor capacitor
CR
= diode
DS
= d e v i c e signaling (lamp)
E
F
J
=
=
= misc. electronic part f u s e jack
K
= relay
L
= inductor
M
= meter
P = plug
Q
= transistor
R = r e s i s t o r
RT = thermistor
S = switch
T
V
=
= transformer vacuum tube, neon bulb, photocell, etc.
X
= s o c k e t
XF
= fuseholder xDS = lampholder
Z = network
K
obd
prv
rect rot rms s-b sect
S i
,s
il sl td
P
PC
P f
PP
PPm
POS paly
Pot
ABBREVIATIO NS to1 trim twt var w/
W
WW w/o cmo
=
=
= kilg
=
1000 order by description
= peak
= printed circuit board picofarads
=
10'12 farads
= peak- to- peak
= parts per million
=
=
= position (s) polystyrene potentiometer
=
= peak reverse voltage rectifier
= rotary
=
= root-mean-square slow-blow
=
=
=
= section (s) silicon silver s l i d e
=
=
=
=
=
=
=
= time delay titanium dioxide toggle tolerance trimmer traveling wave tube variable with
=
= watts wirewound
= without
= . cabinet mount only
AB
B
Beede
Buss
Carling
CTS
Elco
GE
GI
HH
Hoff
Allen-Bradley
Bendix Corporation
Beede Elec.
Instr. Co.
Bussman Mfg. Company
Carling Electric Company
CTS Corpora tion
Elco Corporation
General Electric Company
General Instrument Company
Hardwick-Hindle Company
Hoffman Electric Company
MANUFACTURERS
Kul
ka
Mot.
RCA
Reliance
Mica
S emcor
Sloan
.
S prague
Superior
S ylv
TI
WL
Kulka Electric
Motorola, Inc.
Radio Corporation of America
Reliance Mica Corporation
Semcor Corporation
Sloan Company
S prague Electric
Superior
E lectric
Sylvania Electric
Texas Instruments
Ward Leonard Electric
A. Test Paints 31-33
5 )Isec/cm. Sv/cm
".
.
S l r m A C "
"111.6E
D . Waveforms
B
and
O
superimposed
B.
Test Points 29-33
1
ms/cm, Iv/cm
E . Same a s
B,
except smaller load used
(2v, 3.3)
G .
Waveforms E and F superimposed
A.
Test Points 45-ACC
2ms/cm, 50v/cm
C . Test Points 37-33
Im s/crn, lv/crn
F. Same a s C , except
0 7 fires later due t o smaller load
(2v. 3a)
I. Test Points 45-AC
2ms/cm. 50v/cm
J. Test Points 47-45
2 rns/cm, lOv/cm
K . Test Points 48-18
2 mdcm. O.2v/crn
All waveforms were taken with 115-volt, 60-cps, single-phase input and 32vdc,
1 0 ampere load (except E and F a s indicated). Waveforms H and I require the oscil- loscope t o be ungrounded. If i t is not desirable to unground the oscilloscope, u s e a 1-kva isolation transformer between the input power source and the power supply power input.
WARNING
If the oscilloscope is ungrounded, injury can occur if personnel touch the oscillo- scope c a s e and other equipment simultan- eously.
PATENT APPLIED
F O E
ON
T U I 5
C l e C u l T .
LICENSE
TO
U S E
MUST BE O B T A I N E D IN W E l T l h l G
F L O W
U A L L I S O N L A B O ~ P T D U ~ E S of
2
* D E N O T E S
2 0
P P M W l e E
TEMP COCFF.
5
-
6 , -
-
VOLT&&-E
S1GNA.L.
- -
DENOTES
C L
&SENT
S I G N Q L ,
Berkeley Heights, N.J.
Div of Hewlett-Packard
HEWLETT
PACKARD
--
L a m v I s I o N
3
'
The information contained in this booklet is intended for the operation and mainte- nance of Harrison equipment and is not to be reproduced without written consent of:
Harrison Division of Hewlett-Packard Company
AA4DF Scans Are Reproduced With Permission, Courtesy Of Agilent Technologies, Inc.
PATENT NOTICE
Patents have been applied for on circuits used in this power supply. Buyer is not licensed to reproduce drawings or to utilize the circuit without written permis- sion from Harrison Division of Hewlett-Packard Company.
'
CLAIM
FOR DAMAGE IN SHIPMENT
This equipment should be tested as soon as it is received. If it fails to operate prop- erly or is damaged in any way, a claim should be filed with the carrier.
A full re- port of the damage should be obtained by the claim agent, and this report should be forwarded to us. We will then advise you of the disposition which is to be made of the equipment and arrange for repair or replacement.
HARRISON DIVISION OF HEWLETT-PACKARD C O M P A N Y
100 LOCUST AVENUE BERKELEY HEIGHTS, NEW JERSEY 07922 464-1234 AREA CODE 201 TWX 201-464-2117
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