HP 6259B Service manual

REGULATED DC POWER SUPPLY
MODELS 6259B, 6260B,
6261B, 6268B, 6269B
* OPERATING AND SERVICE MANUAL FOR
MODEL 6259B, SERIALS 1535A-00651 AND ABOVE
MODEL 6260B, SERIALS 1545A-01026 AND ABOVE
MODEL 6261B, SERIALS 1543A-00551 AND ABOVE
MODEL 6268B, SERIALS 1539A-01481 AND ABOVE
MODEL 6269B, SERIALS 1535A-01631 AND ABOVE
* For instruments with serial numbers above those
listed, a change page may be included.
HP Part No. 5950-1766 Printed: March, 1976

TABLE OF CONTENTS
Section Page
I GENERAL INFORMATION _1-1
1-1 DESCRIPTION .11
1-8 SPECIFICATIONS .1-1
1-10 OPTIONS .1-2
1-12 INSTRUMENT/MANUAL
IDENTIFICATION.1-2
1- 15 ORDERING ADDITIONAL
MANUALS .1-3
II INSTALLATION . 2 1
2- 1 INITIAL INSPECTION.2-1
2-3 Mechanical Check .2-1
2-5 Electrical Check.: . . 2-1
2-7 INSTALLATION DATA .2-1
2-9 Location and Cooling .2-1
2-11 Outline Diagram.2-1
2-13 Rack Mounting .2-1
2-15 INPUT POWER
REQUIREMENTS .2-1
2-17 INPUT LINE VOLTAGE OR
FREQUENCY CONVERSION . 2-2
2-20 Converting a Standard Instrument
to 208-Volt Operation (Models
6259B, 6261 B, and 6268BL . . 2-2
2-22 Converting a Standard Instrument
to 208-Volt Operation (Models
6260B and 6269B).2-2
2-24 Converting a Standard Instrument
to 115-Volt Operation (Models
6259B, 6261 B, and 6268B). . . 2-2
2-26 Converting a Standard Instrument
to 115-Volt Operation (Model
6260B) .2-3
2-28 Converting a Standard Instrument
to 50Hz Operation .2-3
2 30 INPUT POWER CONNECTIONS . 2-3
2- 32 REPACKAGING FOR
SHIPMENT.24
II! OPERATING INSTRUCTIONS .3-1
3- 1 TURN-ON CHECKOUT
PROCEDURE.3-1
3-3 OPERATING MODES.3-2
3 6 NORMAL OPERATING MODE. . 3-2
3-8 Constant Voltage Operation .... 3-2
3-10 Constant Current Operation .... 3-2
3-12 Overvoltage Trip Point
Adjustment.3-2
Section Page
III 3-15 Connecting The Load .3-3
(con't.) 3-20 Operation With No Load.3-3
3-22 Operation Beyond Rated
Output .3-3
3-24 OPTIONAL OPERATING
MODES.3-3
3-27 Remote Voltage Sensing .3-3
3-34 Remote Programming .3-5
3-51 Auto-Parallel Operation.3-8
3-57 Auto-Series Operation.3-8
3-67 Auto-Tracking Operation.3-10
3-76 SPECIAL OPERATING
CONSIDERATIONS.3 12
3-77 Pulse Loading.3-12
3-79 Output Capacitance.3-12
3-82 Reverse Voltage Protection .... 3-12
3-85 Reverse Current Loading.3-12
3-87 Battery Charging.3-12
3- 91 Battery Discharging.3-13
IV PRINCIPLES OF OPERATION . . 4 1
4- 1 OVERALL BLOCK
DIAGRAM DISCUSSION_4-1
4-16 DETAILED CIRCUIT
ANALYSIS.4-3
4-17 Preregulator Control Circuit .... 4-3
4-27 Overvoltage Limit Circuit.4-4
4-29 Series Regulator and Driver .... 4-4
4-31 Short-Circuit Protection .4-4
4-33 Constant-Voltage Comparator ... 4-4
4-40 Constant-Current Comparator ... 4-5
4-45 Voltage Clamp Circuit.4-6
4-48 Mixer and Error Amplifiers .... 4-6
4-52 Overvoltage Protection Crowbar. . 4-6
4-58 Turn-On Control Circuit .4-7
4-61 Reference Regulator.4-7
4-66 Meter Circuit.4-7
4- 70 Additional Protection Features . . 4-7
V MAINTENANCE.5-1
5- 1 INTRODUCTION .5-1
5-3 TEST EQUIPMENT
REQUIRED.5-2
5-5 PERFORMANCE TEST.5-2
5-7 CONSTANT-VOLTAGE TESTS. . 5-2
5 38 CONSTANT-CURRENT TESTS. . 5-6
5-49 TROUBLESHOOTING.5-8
iii

TABLE OF CONTENTS (Continued)
Section Page Section
Page
V
5-54
OVERALL TROUBLE-
V
5-100 Ripple Balance Adjustment . . . 5-19
(con't.) SHOOTING PROCEDURES
. 5-8
(con't.)
5-102
Preregulator Tracking
5-60
Disassembly Procedures . . 5-15 Adjustment . . . 5-20
5-69 REPAIR AND REPLACEMENT
. 5-16
5-104 Crowbar Trip Voltage
5-71 ADJUSTMENT AND
Adjustment. . . 5-20
CALIBRATION .
. 5-16
5-106
Maximum Crowbar Trip
5-73
Meter Zero Adjustment. . 5-16
Voltage Adjustment.
. . 5-20
5-75
Voltmeter Calibration .
. 5-16
5-108
Disabling the Crowbar . . . .
. . 5-20
5-77 Ammeter Calibration .
. 5-17
5-79
Constant-Voltage Programming VI REPLACEABLE PARTS . . . 6-1
Calibration.
. 5-17
5-89
Constant-Current Programming
VII CIRCUIT DIAGRAM AND
Calibration.
. 5-18
COMPONENT LOCATION
5-98 Load Transient Recovery Time DIAGRAMS . . . 7-1
Adjustment .
. 5-19
IV

SECTION I
GENERAL INFORMATION
1-1 DESCRIPTION
1 -2 The five constant-voltage/constant current power
supply models included in this manual use a transistor
series-regulator combined with a triac preregulator for high
efficiency, excellent regulation, and low ripple and noise.
These supplies are packaged in 7-inch high full-rack-width
cabinets that are suitable for either bench or relay rack
operation.
1 -3 The outputs of these supplies can be varied from
zero to full rated voltage or current by setting coarse and
fine voltage and current controls on the front panel or they
can be programmed remotely by resistance or voltage inputs
to rear panel terminals. When the voltage controls are used
to establish a constant output voltage, the current controls
establish a current limit that can protect the load from over¬
current. When the current controls are used to establish a
constant output current, the voltage controls establish a
voltage limit that can protect the load from excessive
voltage. The crossover from constant-voltage to constant-
current operation, or vice versa, occurs automatically when
the load current reaches the value established by the current
controls or the voltage reaches the value established by the
voltage controls. The output voltage and current can both
be monitored continuously on front panel meters.
1-4 Output loads are further protected by a built-in
fast-acting overvoltage protection crowbar circuit that
automatically shorts the supply's output terminals if a
preset voltage limit is exceeded. A front panel control sets
the voltage at which the crowbar trips and can be adjusted
from approximately 10% to 110% of the supply's maximum
rated voltage. When several supplies are installed in the
same system, whether in series, parallel, or independently,
their crowbar circuits can be interconnected so that all will
trip simultaneously whenever any one of them does.
1 -5 These power supplies are forced air cooled.
1-6 The ac input connections to these supplies are made
at rear panel terminals. All dc output, remote sensing, and
remote programming connections are also made at rear
panel terminals. Either the positive or negative output
terminal of a supply may be grounded or the supply's
output may be floated at up to 300 volts above ground.
1-7 Remote programming, remote sensing, and several
methods of operating supplies in combination of two or
three are made possible by rear panel terminals that allow
access to control points within the regulator circuits. These
capabilities are described below.
a. Remote Programming. The power supply's output
voltage or current (or both) can be controlled from a remote
location by varying a resistance or a voltage input signal to
the supply's voltage or current regulator circuit.
b. Remote Sensing. Connecting the voltage regulator's
feedback circuit to the load terminals rather than to the
supply's output terminals prevents the voltage drop in the
load leads from impairing voltage regulation at the load
when operating in the constant voltage mode. A separate
pair of sensing leads which carry no load current extend
the feedback loop to the load terminals.
c. Auto-Parallel Operation. Two or three similar
supplies connected in parallel can be made to share loads
equally and can be controlled by the voltage and current
controls (or remote programming terminals) of one of the
supplies designated the master if they are connected for
auto-parallel operation. Normally, only supplies having
the same model number are connected in auto-parallel, but
auto-parallel operation can be used with any of the supplies
covered by this manual that have equal current capabilities.
d. Auto-Series Operation. Two or three supplies can
be connected in series and have their outputs simultaneously
controlled by the voltage and current controls (or remote
programming terminals) of one of the supplies designated
the master. The voltage contributed by each slave is main¬
tained in a constant ratio to that of the master. These
ratios can be set as desired. Auto-series operation provides
higher output voltages in constant voltage operation and
greater voltage compliance in constant current operation.
Any HP supply that offers auto-series operation can serve
as a slave supply; the master supply does not have to be an
auto-series model.
e. Auto-Tracking Operation. Auto-tracking is similar
to auto-series operation except that two or three supplies
share a common negative output bus and are interconnected
so that the output voltage of each slave supply is maintained
at some constant fraction of that of the master supply. All
of the supplies are controlled through the master supply,
and each supply feeds a separate load.
1-8 SPECIFICATIONS
1-9 Detailed specifications for these power supplies
are given in Table 1 -1.
M

1-10 OPTIONS
Option No.
Description
1-11 Options are customer-requested factory modifica¬
tions of a standard instrument. The following options are
available for the instruments covered by this manual. Where
necessary, detailed coverage of the options is included
throughout the manual.
Option No. Description
005 Realign ment for 50Hz Operation : Standard
instruments are designed for 57 to 63Hz
operation. For 50Hz operation, a resistor
in the preregulator control circuit is changed
and the preregulator is realigned.
007 T en-Turn Output Voltage Control: A ten-
turn control replaces the coarse voltage con¬
trol for improved resolution in setting the
output voltage.
008 Ten-Turn Output Current Control: A ten-
turn control replaces the coarse current
control for improved resolution in setting
the output current.
009 Ten-Turn Output Voltage and Current
Control s: This option includes Options
007 and 008 in the same instrument.
010 C hassis Slides : Factory installed slides
permit convenient access to the interior of
a rack mounted supply for maintenance.
013 Three-Digit Graduated Decadial Voltage
Control: To improve mechanical stability
and permit accurate resetting of the output
voltage, Option 013 replaces the coarse
voltage control with a ten-turn control
equipped with a 3-digit turns-counting dial.
014 Three-Digit Graduated Decadial Current
Control : To improve mechanical stability
and permit accurate resetting of the output
current. Option 014 replaces the coarse
current control with a ten-turn control
equipped with a 3-digit turns-counting dial.
016 Rewiring for 11 5Vac ±10% Single-Phase
Input (Model 6260B only): This factory
modification replaces the circuit breaker
and power transformer, adds a resistor to the
A2 assembly, and reconnects the bias trans¬
former, preregulator choke, and fans for
11 5Vac operation.
020 Adjustable Voltage Programming : Two
screwdriver-adjustable controls accessible
through holes in the rear panel allow the
voltage programming coefficient and zero
output voltage to be adjusted conveniently
to an accuracy of 0.1%.
021 Adjustable Current Programming: Two
screwdriver-adjustable controls accessible
through holes in the rear panel allow the
current programming coefficient and zero
output current to be adjusted conveniently
to an accuracy of 0.1%.
022 Adjustable Voltage and Current Programming:
This option includes Options 020 and 021
in the same instrument.
026 Rewiring for 11 5Vac ±10% Single-Phase
Input (Models 6259B, 6261 B, and 6268B only):
This factory modification replaces the circuit
breaker (except in the Model 6259B), adds
a resistor to the A2 assembly, and reconnects
the power transformer, bias transformer,
preregulator choke, and fans for 115Vac
operation.
027 Rewiring for 208Vac +10% Single-Phase
Input: This factory modification reconnects
the power and bias transformers for 208Vac
operation.
040 Interfacing for Mu ltiprogrammer Operation :
This factory modification prepares standard
power supplies for resistance programming
by the 6940B Multiprogrammer or the
6941 B Multiprogrammer Extender. Operation
with either of these instruments requires that
the power supply be subjected to a special
calibration and a protection checkout. The
special calibration insures that the power
supply can be accurately set to zero and to
the maximum rated output voltage or current
when programmed by the multiprogrammer.
The protection checkout insures that the
power supply will not be damaged by the
rapid repetitive programming possible with
the multiprogrammer. This option includes
Option 022.
1-12 INSTRUMENT/MANUAL IDENTIFICATION
1-13 Hewlett-Packard power supplies are identified by a
1-2

two-part serial number. The first part is the serial number
prefix, a number-letter combination that denotes the date
of a significant design change and the country of manu¬
facture. The first two digits indicate the year (10 = 1970,
11 = 1971, etc.), the second two digits indicate the week,
and the letter "A” designates the U. S. A. as the country
of manufacture. The second part is the power supply serial
number. A different sequential number is assigned to each
power supply, starting with 001 01.
1-14 If the serial number on your instrument does not
agree with those on the title page of the manual. Change
Sheets supplied with the manual define the differences
between your instrument and the instrument described
by this manual.
1-15 ORDERING ADDITIONAL MANUALS
1-16 One manual is shipped with each power supply.
Additional manuals may be purchased from your local
Hewlett-Packard field office (see list at rear of this manual
for addresses). Specify the model number, serial number
prefix, and HP part number shown on the title page.
Table 1-1 Specifications: Models 6259B, 6260B, 6261B, 6268B, 6269B
INPUT:
230Vac ±10%, single phase, 57-63Hz for the standard
models. (For other input voltages or 50Hz operation, see
the option listings in paragraph 1-10. Input power require¬
ments are listed in paragraph 2-1 5.
OUTPUT:
Model 6259B 0-10 volts at 0-50 amps
6260B 0-10 volts at 0-100 amps
6261 B 0-20 volts at 0-50 amps
6268B 0-40 volts at 0-30 amps
6269B 0-40 volts at 0-50 amps
LOAD EFFECT (LOAD REGULATION):
Constant Voltage — Less than 0.01% of output plus 200pV
for a load change equal to the current rating of the supply.
Constant Current —
Models 6259B and 6261 B - Less than 0.02% of output
plus 1 mA for a load change equal to the voltage rating of
the supply.
Models 6260B, 6268B, and 6269B - Less than 0.02%
of output plus 2mA for a load change equal to the voltage
rating of the supply.
SOURCE EFFECT (LINE REGULATION):
Constant Voltage - Less than 0.01 % of output plus
200pV for a change in line voltage between 208 and 254Vac
(or 104 and 1 27Vac) at any output voltage and current
within rating.
Constant Current -
Models 6259B and 6261 B - Less than 0.02% of output
plus 1 mA for a change in line voltage between 208 and 254Vac
(or 104 and 127Vac) at any output voltage and current
within rating.
Models 6260B, 6268B, and 6269B - Less than 0.02%
of output plus 2mA for a change in line voltage between
208 and 254Vac (or 104 and 127 Vac) at any output voltage
and current within rating.
PARD (RIPPLE AND NOISE):
(Measured within 20Hz to 20MHz bandwidth)
Model
Constant Voltage
Constant Current
6259B
500pVrms/5mV p-p
25mA rms
6260B
500pVrms/5mV p-p 50mA rms
6261 B
500pVrms/5mV p-p 25mA rms
6268B
1 mVrms/5mV p-p 20mA rms
6269B
1mVrms/5mV p-p 25mA rms
TEMPERATURE COEFFICIENT:
Constant Voltage - Less than 0.01% plus 200pV change
in output per degree Celsius change in ambient following
a 30-minute warmup.
Constant Current -
Models 6259B, 6261 B, and 6269B - Less than 0.01 %
plus 4mA change in output per degree Celsius change in
ambient following a 30-minute warmup.
Model 6260B - Less than 0.01 % plus 8mA change
in output per degree Celsius change in ambient following
a 30-minute warmup.
Model 6268B - Less than 0.01% plus 2mA change
in output per degree Celsius change in ambient following
a 30-minute warmup.
DRIFT (STABILITY):
(Change in output (dc to 20Hz) over an 8-hour interval
under constant line, load, and ambient temperature follow¬
ing a 30-minute warmup.)
Constant Voltage - Less than 0.03% of output plus 2mV.
Constant Current —
Models 6259B, 6261 B, and 6269B - Less than 0.03%
of output plus 10mA.
Model 6260B - Less than 0.03% of output plus 20mA.
Model 6268B - Less than 0.03% of output plus 5mA.
1-3

Table 1-1 Specifications: Models 6259B, 6260B, 6261B, 6268B, 6269B (Continued)
LOAD TRANSIENT RECOVERY TIME:
Less than 50/Jsec is required for output voltage recovery
(in constant voltage operation) to within lOmV of the
nominal output following a change in output current equal
to the current rating of the supply or 5 amps, whichever
is smaller.
REMOTE PROGRAMMING COEFFICIENTS:
Output Voltage Programming —
Resistance
Voltage
Model Control (±1 %)
Control (±1%)
All Models
200JT2/V
1V/V
Output Current Programming —
Resistance Voltage
Model Control (±10%) Control (±10%)
6259B 4I2/A
lOmV/A
6260B 2£2/A 5mV/A
6261 B 4L2/A
10m V/A
6268B 6J2/A
16.7mV/A
6269 B
4L2/A 1 OrnV/A
REMOTE PROGRAMMING SPEED:
(Typical time required to nonrepetitively change from
zero to within 99.9% of the maximum rated output voltage
or from the maximum rated output
of that voltage above zero.)
voltage to within 0.1 %
Model
Up, Full Load Down, Full Load
6259B
70ms
10ms
6260B
70ms
5ms
6261 B
1 50ms
25ms
6268B
300ms
30ms
6269B
350ms
20ms
Model
Up, No Load Down, No Load
6259B
70ms
200ms
6260B
70ms
200ms
6261 B 1 50ms
250ms
6268B
300ms Isec
6269B
350ms Isec
PANEL METERS:
The accuracy of the front panel voltmeter and ammeter
is ±2% of full scale. The ranges of these meters are:
Model Model
6259B 12V,60A 6268B 50V,35A
6260B 12V, 120A 6269B 50V, 60A
6261 B 24V, 60A
TEMPERATURE RATINGS:
Operating 0 to 55'C Storage -40 to +75 C
COOLING:
These power supplies are forced air cooled. The Model
6259B is cooled by a single fan; the other models are cooled
by two fans.
RESOLUTION:
(Minimum output voltage or current change that can
be obtained using the front panel controls.)
Model Constant Voltage Constant Current
6259 B 1 m V 50mA
6260B 1 mV 100mA
6261B 2mV 50mA
6268B 5m V 30mA
6269B 5m V 50mA
OUTPUT IMPEDANCE (TYPICAL):
Approximated by a resistance in series with an inductance
as follows:
Model Model
6259B 0.05mft, IpH 6268B 0.2m£2, 1/uH
6260B 0.02m£2, IpH 6269B 0.1m£2, IpH
6261 B 0.01mS2, IpH
OVERVOLTAGE PROTECTION CROWBAR:
To avoid false tripping, the recommended trip margin
above the output voltage is 5% of the output voltage plus
2 volts for Models 6259B, 6260B, and 6261 B, and 5% of
the output voltage plus 1 volt for Models 6268B and 6269B.
The approximate crowbar trip voltage ranges are:
Model Model
6259B 2V-12V 6268B 4V-45V
6260B 2V-12V 6269B 4V-45V
6261 B 2V-23V
OPTIONS AVAILABLE:
(See paragraph 1-10 for descriptions)
All Models - Options 005, 007, 008, 009, 010, 013,
014, 020, 021, 022, 027, 040.
Model 6260B only — Option 016.
Model 6259B, 6261 B, and 6268B only — Option 026.
INPUT POWER CONNECTIONS:
Input power is connected by way of a 3-terminal barrier
Trip on the rear panel.
DIMENSIONS:
(See Figure 2-1 outline diagrams.)
WEIGHT:
Model
Net
Shipping
6259B
69 lbs. (31.3 kg)
78 lbs. (35.3 kg)
6260B 97 lbs. (43.9 kg) 106 lbs. (48.0 kg)
6261 B
78 lbs. (35.3 kg)
87 lbs. (39.4 kg)
6268B
76 lbs. (34.4 kg) 84 lbs. (38.1 kg)
6269B 89 lbs. (40.3 kg)
98 lbs. (44.0 kg)
1-4

SECTION II
INSTALLATION
2-1 INITIAL INSPECTION
2-2 Before shipment, this instrument was inspected
and found to be free of mechanical and electrical defects.
As soon as the instrument is unpacked, inspect for any
damage that may have occurred in transit. Save all
packing materials until the inspection is completed. If
damage is found, file a claim with the carrier immediately.
The Hewlett-Packard Sales and Service office should be
notified as soon as possible.
2-3 Mechanical Check
2-4 This check should confirm that there are no
broken knobs or connectors, that the cabinet and panel
surfaces are free of dents and scratches, and that the
meters are not scratched or cracked.
2-5 Electrical Check
2-6 The instrument should be checked against its
electrical specifications. Section V includes an "in-cabinet”
performance check to verify proper instrument operation.
2-7 INSTALLATION DATA
2-8 The instrument is shipped ready for permanent
rack installation or bench operation. It is necessary only
to connect the instrument to a source of power and it is
ready for use.
2-9 Location and Cooling
2-10 These instruments are fan-cooled and must be
installed with sufficient space for cooling air to reach their
sides. These power supplies should be used in an area
where the ambient temperature does not exceed 55"C.
2-11 Outline Diagram
2-1 2 Figure 2-1 shows the outline shape and dimensions
of these supplies.
2-13 Rack Mounting
2-14 This instrument is full rack size and can be easily
rack mounted in a conventional 19-inch rack panel using
standard mounting screws.
TERMINAL STRIP DETAIL
-esi;te
.*•:«»« 5.1 n sing
336=? tEPM
0 52 -!/«• 70
ffrON' Cl¥ENOCHS
6 9e8:ir?*<p' ■*
9C0C"4$2 6nr.' *1*
5 50'.4 8»t i
TOP
3'S
• 54 9mr»|
JJSCC --•».
SIDE
Figure 2-1. Outline Diagrams
(Models 6259B, 6260B, 6261B, 6268B, and 6269B)
2-15 INPUT POWER REQUIREMENTS
2-16 The standard instrument is wired for a nominal
input of 230Vac 57-63Hz when it is shipped from the factory.
The supplies covered by this manual are also available
equipped for a 208-volt input (Option 027), and except for
the Model 6269B, are also available equipped for a 115-volt
input (Option 026 for Models 6259B, 6261 B, and 6268B,
or Option 016 for the Model 6260B). In addition, all five
models are available in a 50Hz version. The input voltage
and frequency required is marked on the rear panel of the
supply. Except for the Model 6269B, which cannot be
converted to 11 5-volt operation, a standard instrument can
be converted by the user to 208 or 11 5-volt and to 50Hz
operation by following the instructions given in the follow¬
ing paragraphs. The standard instrument requires the input
current and power listed below when operated at full load
from a 230-volt source. When the supply is operated from
a 115-volt source, the input current is approximately twice
the amount listed.
Model Input Current Input Powe
6259B
6A
850W
6260B
12A
1600W
6261B
12A
1500W
6268B
12A 1600W
6269B
18A
2500W

2-17 INPUT LINE VOLTAGE OR
FREQUENCY CONVERSION
2-1 8 Converting a 230-volt instrument to 208-volt
operation is simply a matter of changing some taps or
jumper connections on main power transformer T1 and bias
transformer A3T2. Converting to 11 5-volt operation is
more involved. The Models 6259B, 6260B, 6261 B, and
6268B require an added resistor and some jumper changes
in the A2 RFI assembly and a changed A3T2 transformer
tap. In addition, the 6260B, 6261 B, and 6268B need a
replacement circuit breaker, and the 6260B needs a replace¬
ment T1 power transformer. Complete line voltage con¬
version instructions are given in paragraphs 2-20 through
2-27.
2-19 Converting a 60Hz instrument to 50Hz operation
requires that one resistor be replaced and some adjustments
be made. Line frequency conversion instructions are given
in paragraph 2-28.
2-20 Converting a Standard Instrument to 208-
Volt Operation (Models 6259B, 6261B and 6268B).
2-21 To convert these 230-volt instruments to 208-volt
operation, proceed as follows:
a. Disconnect instrument from power source and remove
top and bottom covers.
b. Remove A2 RFI assembly as described in steps (a)
through (c) of paragraph 5-65. This provides access to bias
transformer A3T2 (see Fig. 7-2).
c. Locate the wire that connects circuit breaker CB1 to
the A3T2 bias transformer terminal marked "230V”,
disconnect it from the transformer, and reconnect it to
the terminal marked "208V". Leave the wire from fan B2
(not used in the 6259B) connected to the terminal marked
"230V" (see Fig. 2-2B).
d. Re-install the RFI assembly by reversing the proce¬
dure of step (b) above.
e. Unsolder the wire connected to terminal 5 of power
transformer T1 and solder it instead to terminal 4 (see
Figure 2-3B).
2-22 Converting a Standard Instrument to 208-
Volt Operation (Models 6260B and 6269B).
2-23 To convert these 230-volt instruments to 208-
volt operation, proceed as follows:
a. Perform steps (a) through (d) of paragraph 2-21.
b. Unsolder the wire connected to the terminal marked
"230V" on power transformer T1 and solder it instead to
the terminal marked "208V" (see Fig. 2-4B).
2-24 Converting a Standard Instrument to 115-
Volt Operation (Models 6259B, 6261B and 6268B).
A
BIAS TRANSFORMER
(A3T2) CONNECTIONS
FOR 230 VOLT
OPERATION.
B
BIAS TRANSFORMER
(A3T2) CONNECTIONS
FOR 208 VOLT
OPERATION.
C
BIAS TRANSFORMER
(A3T2) CONNECTIONS
FOR 115 VOLT
OPERATION.
NOTE- X FAN B2 IS NOT USED
IN MODEL 62596
Figure 2-2. Bias Transformer Primary Connections
for 208Vac Operation (Modal 6259B, 6260B, 6261B,
6268B, and 6269B) and 115Vac Operation
(except Model 6269B).
2-2