HP 6826A Service manual

BIPOLAR
POWER SUPPLY/AMPLIFIER
MODELS 6826A AND 6827A
Valuetronics
Internationa
1 - 8 0 0 -
OPERATING AND SERVICE MANUAL
FOR SERIALS 1317A-00101 AND ABOVE*
*For Serials Above 1317A-00101
a change page may be included.
HEWLETT-PACKARD
Part No. 5950-1702
Printed: November, 1974

SECTION I
GENERAL INFORMATION
1-1 DESCRIPTION
1-2 This instruction manual contains operating and
service instructions for two Bipolar Power Supply/Amplifiers
(Models 6826A and 6827A). The Bipolar Power Supply/
Amplifier (BPS/A) is a general purpose instrument useful in
any laboratory engaged in the research and development of
electronic systems, circuitry, or components. The BPS/A
can be operated as a power supply or as an amplifier. Ter¬
minals on the rear terminal strip permit access to various in¬
ternal control points to further expand the operational cap¬
abilities of the unit. The resulting flexibility lends the BPS/A
to an almost unlimited number of applications. Some of
these applications are outlined in Section ill of this manual.
The following paragraphs describe some of the features of
the BPS/A as a power supply and as an amplifier.
1-3 POWER SUPPLY FEATURES
1-4 The unit can be made to function as a regulated dc
power supply by setting the front panel MODE switch to
the POWER SUPPLY position. The supply can furnish
either a Constant Voltage output or Constant Current out¬
put. The dc output is bi-polar and is continuously adjustable
from its maximum rated positive value to an equal negative
continuously through zero. A crossover feature automati¬
cally changes the supply from constant voltage to constant
current operation at a preset or programmed voltage/current
point. The front pane! CURRENT MODE indicator lights
for constant current operation. Both the supply and the
load are protected against overvoltage and overcurrent
conditions by internal circuits. Dual output voltage ranges
are provided for better resolution. The front panel RANGE
switch allows selection of the high (X10) or low (XI) output
range.
1-5 The output voltage can be programmed locally
using the front panel VOLTAGE control, or remotely, by
means of a resistance connected to the appropriate rear ter¬
minals. The output current can be programmed locally us¬
ing the front panel CURRENT control, or remotely, by
means of a resistance or voltage source connected to the
appropriate rear terminals. The BPS/A can be programmed
(controlled) at a very high rate of speed (less than BOpsec
for output voltage change over the entire voltage span).
Local and remote programming connections are described
in Section III. The output voltage and current ranges are
as follows;
Model 6826A: -5V to +5V at 0 to 1.0A (low range)
--50V to +50V at 0 to 1.0A (high range)
Model 6827A: -10V to +10V at 0 to 0.5A (low range)
-100V to +100V at 0 to 0.5A (high range)
1-6 The BPS/A can sink, as well as source current, per¬
mitting it to serve as a variable load device. The BPS/A can
sink up to 50% of the rated output current.
1-7 AMPLIFIER FEATURES
1-8 The unit can be made to function as a variable gain
or a fixed gain amplifier by setting the MODE switch to the
VAR GAIN AMP or FXD GAIN AMP position. When oper¬
ating as an amplifier, the BPS/A can amplify externally
applied ac or dc signals. Variable gain can be controlled
locally (VOLTAGE control) or remotely and is accurate to
0.1%. The variable or fixed gain provided is as follows;
Model 6826A: Variable Gain
Fixed Gain
Model 6827A: Variable Gain
Fixed Gain
0-2 (low range), 0-20
(high range)
IX (low range) 10X
(high range)
0-4 (low range), 0-40
(high range)
2X (low range), 20X
(high range)
1-9 The variable gain amplifier is non-inverting and has
a frequency response from dc to 15kHz. The fixed gain
amplifier is inverting and has a frequency response from dc
to 40kHz (6826A) or from dc to 30kHz (6827A). Total
harmonic distortion is 0.1% (maximum).
1-10 METERS
1-11 A voltmeter and an ammeter on the front panel
monitor the ac or dc output voltage and current respective¬
ly. Associated front panel VOLTAGE METER and CUR¬
RENT METER switches allow the meters to monitor either
an ac or dc output and also provide dual range monitoring
capability for better resolution. The dc meter accuracy is
±3% of full scale and the ac meter accuracy is ±5% of full
scale.
1-12 SPECIFICATIONS
1-13 Detailed specifications for the two models are
given in Table 1-1.
1-1

Table 1-1. Specifications, Models 6826A and 6827A
NOTE
Specifications apply to all models unless otherwise specified.
GENERAL SPECIFICATIONS
Input Power:
Model 6826A: 104-127/208-254Vac (switchable),
48-63Hz, 1.0A, 130W
Model 6827A: 104-127/208-254Vac (switchable),
48-63Hz, 1.2A, 150W
Meters:
Individual voltage and current meters. DC accuracy is
3% of full scale. AC accuracy is 5% full scale with sinu¬
soidal, 100Hz input.
Meter Ranges (DC):
M o del 6826 A : ±6V,±60V
±0.12A, ±1.2A
Model 6827 A: ±12V, ±120V
±0.06A, +0.6A
Meter Ranges (AC):
Model 6826A: 4V (uncal), 40V rms
0.08A rms, 0.8A rms
Model 6827A: 8V (uncal), 80V rms
0.04A rms, 0.4A rms
Temperature Ratings:
Operating: 0 to 55°C.
Storage: --40 to +75°C,
Cooling:
Convection cooling is employed. The supplies have no
moving parts.
Dimensions:
See outline diagram. Figure 2-1.
Weight:
18 lbs. (8.2 kg.) net, 21 lbs. (9.5 kg.) shipping.
POWER SUPPLY SPECIFICATIONS
DC Output:
Voltage and current spans indicate range over which
output may be varied.
Model 6826 A :
XI Range: —5V to +5V, 0 to 1.0A
X10 Range: -BOV to +50V, 0 to 1.0A
DC Output (Continued):
Model 6827A:
XI Range: -10V to+10V, 0 to 0.5A
X10 Range: -100V to +100V, 0 to 0.5A
Load Effect (Load Regulation):
Voltage load effect is given for a load current change
equal to the current rating of the supply. Current load
effect is given for a load voltage change equal to the
voltage rating of the supply.
Model 6826A:
Voltage (XI Range): 0.01%+.5mV
Voltage (XI0 Range): 0.01%+ ImV
Current: .01% + 250/iA
Load Effect (Load Regulation) Continued:
Model 6827A:
Voltage (XI Range): ,01% + .3mV
Voltage (X10 Range): .01%+ImV
Current: ,01% + 250 /kA
Source Effect (Line Regulation):
For a change in line voltage between 104 and 127Vac/
208 and 254Vac at any output voltage and current
within rating.
Model 6826A:
Voltage (XI Range): .01% + .5mV
Voltage (X10 Range): .01% + 5mV
Current: .01% + 250pA
Model 6827A:
Voltage (XI Range): .01%+ ImV
Voltage (XI0 Range): .01%+10mV
Current: .01% + 250/uA
PARD (Ripple and Noise):
Rms/p-p (20Hz to 20MHz) at any line voltage and
under any load condition within rating.
Model 6826A:
Voltage (XI Range): 2mV rms/IGmV p-p
Voltage (X10 Range): 6mV rm$/35mV p-p
Current: 8mA rms/5mA p-p
Model 6827A:
Voltage (XI Range): 2.5mV rms/15mV p-p
Voltage (X10 Range): lOmV rm$/50mV p-p
Current: .4mA rms/5mA p-p
1-2

Table 1-1. Specifications, Models 6826A and 6827A (Continued)
POWER SUPPLY SPECIFICATIONS (Continued)
Model 6826A:
Temperature Coefficient:
Voltage (XI Range): lOmV
Voltage (X10 Range): lOOmV
Current: 3mA
Output change per degree Centigrade change in am-
Model 6827A:
bient following 30 minutes warm-up.
Voltage (XI Range): 20mV
Model 6826A:
Voltage (XI0 Range): 200mV
Voltage (XI Range): ,01% + .35mV
Current: 1.5mA
Voltage (X10 Range): .01% + 3mV
Current: .02% + 50juA
Output Impedance (Typical to 50kHz);
Mode! 6827A:
Approximated by a resistance in series with an indue-
Voltage (XI Range): .01% + .7mV
tance (constant voltage operation).
Voltage (XI0 Range): .01% + 6mV
Model 6826A: 1m£2&1.5qH
Current: .02% + 50juA
Model 6827A: 2mft & 4/uH
Drift (Stability):
DC Output Isolation:
Supply may be floated at up to 300V above ground.
Change in output (dc to 20Hz) over 8 hour interval
under constant line, load, and ambient following 30
Remote Resistance Programming:
minutes warm-up.
Mode! 6826A (Resistance Coefficient):
Model 6826A:
Voltage (XI Range): 2000H/V ± .1%
Voltage (XI Range): .03% + 1 mV (Pot wiper jump
Voltage (XI0 Range): 200£2/V ± .1%
effect may add 5mV)
Current: 10£2/mA + .1%
Voltage (X10 Range): .03%+ lOmV (Pot wiper
Model 6827A (Resistance Coefficient):
jump effect may add 50mV)
Voltage (XI Range): 1000H/V + .1%
Current: .1% + 200;uA (Pot wiper jump effect may
Voltage (XI0 Range): lOOft/V ± .1%
add 1.5mA)
Current: 10£2/mA±.1%
Model 6827A:
Voltage (XI Range): .03% + 2mV (Pot wiper jump
Remote Programming Speed:
effect may add 5mV)
50/isec are required to change between 1% and 99% of
Voltage (X10 Range): .03% + 20mV (Pot wiper
the maximum + and — voltage limits.
jump effect may add lOOmV)
Current: .1% + 200,uA (Pot wiper jump effect may
Remote Programming Temperature Coefficient:
add 1mA).
Output change per degree Centigrade change in am-
Load Effect Transient Recovery (Load Transient
bient using an external control resistor (Rp) at output
voltage (Vo) or current (lo)- % T.C. Rp is the tern-
Recovery):
perature coefficient of the control resistance Rp.
Time required for output voltage recovery to within
Model 6826A:
the specified level of the nominal output voltage
Voltage (XI Range): ,25mV + .007% (Vo) +
following a change in output current equal to the
% T.C. Rp (Vo + 5}
current rating of the supply. Voltage (X10 Range): 2.2mV + .007% (Vo) +
Model 6826A:
% T.C. R F (V 0 + 50)
IQOpsec is required for output voltage recovery
Current: .016% (Iq) + 33pA + % T.C. Rp (l 0 )
within 50mV of nominal output voltage.
Model 6827A:
100/usec is required for output voltage recovery
Model 6827A:
within lOOmV of nominal output voltage.
Voltage (XI Range): ,5mV + .007% (Vq) +
Resolution:
% T.C. Rp (Vq + 10)
Voltage (X10 Range): 4mV + .007% (Vo) +
Typical output voltage or current change that can be
% T.C. Rp (Vq + 100)
obtained using front panel controls.
Current: .016% (Iq) + 33/tA + % T.C. Rp (Iq)
1-3

Table 1-1. Specifications, Models 6826A and 6827A (Continued)
POWER SUPPLY SPECIFICATIONS (Continued)
Sink Current Compliance:
Maximum current that the supply can sink when con¬
nected to an active load.
Model 6826A:
Sink current is limited to a value ranging linearly
from 1A @ OV to .5A @ 50V.
Externally applied voltages to output terminals in
excess of GOV could damage the instrument.
Model 6827A:
Sink current is limited to a value ranging linearly
from ,5A @ 0V to .25A @ 100V.
Externally applied voltages to output terminals in
excess of 125V could damage the instrument.
POWER AMPLIFIER SPECIFICATIONS
Output:
Mode l 6826A:
Voltage (XI Range): 10V p-p
Voltage (XI0 Range): 100V p-p
Current: 1A peak
Model 6827A:
Voltage (XI Range): 20V p-p
Voltage (X10 Range): 200V p-p
Current: ,5A peak
Voltage Gain (High/Low Range):
Model 6826A:
Fixed Amplifier (Inverting): 10X (high range)/
1X(iow range)
Variable Gain (Non-inverting): 0-20 (high range)/
0-2 (low range)
Model 6827A:
Fixed Amplifier (Inverting): 20X (high range)/
2X (low range)
Variable Gain (Non-Inverting): 0-40 (high range)/
0-4 (low range)
Frequency Response (+1, —3dB at full output):
Model 6826 A :
Fixed Gain: dc — 40kHz
Variable Gain: dc—15kHz
Model 6827A:
Fixed Gain: dc —30kHz
Variable Gain: dc—15kHz
Distortion:
Total harmonic distortion is .1% (maximum) at 100
Hz and full output.
Input Impedance:
lOKfi (Typical)
Fixed Gain Accuracy (at 100Hz):
Model 6826A:
Low Range (XI): .1% + .5mV
High Range (X10): .1% + 5mV
Model 6827A:
Low Range (XI): ,1%+lmV
High Range (X10): .1%+10mV
Remote Resistance Programming Variable Gain {Ay):
KR f
Ay ~ - — ——— - f where K is the constant indi-
10.24 x 1 0 ° i2
cated and R p is the external control resistance.
Model 6826A:
R c
Ay at low range (XI):-——
10.24 x 10 3
10 R f
Ay at high range (X10):-
10.24 x 10 3
Model 6827A:
. 2R
Ay at low range (XI): .- —
10.24 x I O 3
, ^ 20 R f
Ay at high range (XI0): . ——-
10.24 x 10 3

Table 1-1. Specifications, Mode! s6826A and 6827A {Continued)
Variable Accuracy:
Accuracy in high range at 100Hz using an external
control resistance (Rp) at output voltage (Vo)- %
Rp is the accuracy of the control resistance Rp.
Model 6826A: (.05% + %R F ) V 0 + 5mV
Model 6827A: (.05% + %Rp) Vo + 10mV
Remote Voltage Control Coefficient:
Fixed gain amplifier mode, voltage coefficient:
Model 6826A:
Voltage (XI Range): 1 volt/volt ± .1%
Voltage (X10 Range): 10 volts/volt ± .1%
Model 6827A:
Voltage (XI Range): 2 volts/volt ± .1%
Voltage (X10 Range): 20 volts/volt ± .1%
Constant Current, voltage coefficient (the following
applies to variable gain amplifier, fixed gain amplifier,
and power supply modes of operation):
Models 6826A and 6827A: 1 ampere/volt ± .5%
1-14 OPTIONS
1-15 Options are customer-requested factory modifica¬
tions of a standard instrument. The option described below
applies to Models 6826A and 6827A.
Option No . Description
007 Ten-turn Output Voltage Control: Replaces
standard single-turn voltage control to allow
greater resolution in setting the output volt¬
age ir gain of the BPS/A. Shunt resistor
A1 R53 as well as standard VOLTAGE con¬
trol (HP Part No. 2100-3272) A5R2 must
be removed when the ten-turn output volt¬
age control (HP Part No. 2100-1867) is in¬
stalled in the A5R2 location.
1-16 ACCESSORIES
1-17 The accessories listed in the following chart, may
be ordered with the instrument or separately from your
local Hewlett-Packard sales office (refer to list at rear of
manual for addresses).
HP Part No.
5060-8762
5060-8760
11057A
1052A
Dual Rack Adapter: Kit for rack mounting
one or two supplies in standard 19-inch rack.
Blank Panel: Filler panel to block unused
half of rack when mounting only one supply.
Carrying handle easily attached for portabil¬
ity and handling convenience.
Combining Case for mounting one or two
units in standard 19-inch rack.
5060-0789 Cooling kit for above combining case, 115
Vac, 50-60Hz.
5060-0796 Cooling kit for above combining case, 230
Vac, 50-60Hz.
1-18 INSTRUMENT IDENTIFICATION
1-19 Hewlett-Packard power supplies are identified by a
three-part serial number. The first part is the power supply
model number. The second part is the serial number prefix,
consisting of a number-letter combination denoting the date
of a significant, design change and the country of manufac¬
ture. The first two digits indicate the year (12 = 1972, 13
= 1973, 20 - 1980, etc); the second two digits indicate the
week (01 through 52); and the letter "A", "G", "J", or "U"
designates the U.S.A., West Germany, Japan, or the United
Kingdom, respectively, as the country of manufacture. The
third part is the power supply serial number; a different 5-
digit sequential number is assigned to each power supply,
starting with 00101.
1-20 If the serial number prefix on your unit does not
agree with the prefix on the title page of this manual, change
sheets supplied with the manual or manual backdating
changes in Appendix A define the differences between your
instrument and the instrument described by this manual.
1-21 ORDERING ADDITIONAL MANUALS
1-22 One manual is shipped with each instrument. Add¬
itional manuals may be purchased from your local Hewlett-
Packard field office (see list at rear of this manual for add¬
resses). Specify the model number, serial number prefix,
and HP part number shown on the title page.

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 received, proceed as instructed in
the following paragraphs.
2-3 MECHANICAL CHECK
2-4 If external damage to the shipping carton is evident,
ask the carrier's agent to be present when the instrument is
unpacked. Check the instrument for external damage such
as broken controls or connectors, and dents or scratches on
the panel surfaces, if the instrument is damaged, file a claim
with the carrier's agent and notify your local Hewlett-Packard
Sales and Service Office as soon as possible (see list at rear of
this manual for addresses).
2-5 ELECTRICAL CHECK
2-6 Check the electrical performance of the instrument
as soon as possible after receipt. Section V of this manual
contains performance check procedures which will verify in¬
strument operation within the specifications stated in Table
1- 1 . This check is also suitable for incoming quality control
inspection. Refer to the inside front cover of the manual
for the Certification and Warranty statements.
2- 7 REPACKAGING FOR SHIPMENT
2-8 To insure safe shipment of the instrument, it is
recommended that the package designed for the instrument
be used. The original packaging material is reusable. If it is
not available, contact your local Hewlett-Packard field office
to obtain the materials. This office will also furnish the add¬
ress of the nearest service office to which the instrument can
be shipped. Be sure to attach a tag to the instrument speci¬
fying the owner, model number, full serial number, and ser¬
vice required, or a brief description of the trouble.
2-9 INSTALLATION DATA
2-10 The instrument is shipped ready for bench opera¬
tion. It is necessary only to connect the instrument to a
source of power and it is ready for operation.
2-11 LOCATION
2-12 This instrument is convection cooled. Sufficient
space should be allotted so that a free flow of cooling air
can reach the top and rear of the instrument when it is in
operation. It should be used in an area where the ambient
temperature remains between 0°C and +55°C.
2-13 OUTLINE DIAGRAM
2-14 Figure 2-1 illustrates the outline shape and dimen¬
sions of Models 6826A and 6827A.
2-15 RACK MOUNTING
2-16 The Mode! 6826A and 6827A BPS/A's may be rack
mounted using either the dual rack adapter kit or the com¬
bining case (with appropriate cooling kit) described in Para¬
graph 1-16. The necessary installation instructions are pro¬
vided with the accessories. Refer to Paragraph 5-91 before
proceeding with the rack mounting installation instructions.
2-1

2-17 INPUT POWER REQUIREMENTS
2-18 Models 6826A and 6827A may be operated contin¬
uously from either a nominal 120 volt or 240 volt, 48-63
Hz power source. A two-position selector switch { | ) loca¬
ted within the a-c power module on the rear panel selects
the power source. Before connecting the instrument to the
power source, check that the selector switch setting matches
the nominal line voltage of the source. If required, move
the switch to the other position. Note that the power cable
must be removed, the plastic door on the power module
must be moved aside, the fuse extractor must be pulled out¬
ward and the fuse must be removed in order to gain access
to the selector switch.
2-19 When the instrument leaves the factory, the proper
fuse is installed for 115 volt operation. An envelope con¬
taining a fuse for 230 volt operation is attached to the instru¬
ment. Make sure that the correct fuse is installed if the
position of the slide switch is changed (2A for 115 volt op¬
eration, and 1A for 230 volt operation).
2-20 POWER CABLE
2-21 To protect operating personnel, the National Elec¬
trical Manufacturers' Association (NEMA) recommends that
the instrument panel and cabinet be grounded. This instru¬
ment is equipped with a three conductor power cable. The
third conductor is the ground conductor and when the cable
is plugged into an appropriate receptacle, the instrument is
grounded. The offset pin on the power cable's three-prong
connector is the ground connection.
2-22 To preserve the protection feature when operating
the instrument from a two-contact outlet, use a three-prong
to two-prong adapter and connect the green lead on the
adapter to ground.
2-2

SECTION ill
DERATING INSTRUCTIONS
Figure 3-1. Bipolar Power Supply/Amplifier, Models 6826A and 6827A, Rear View
3-1 INTRODUCTION
3-2 This section describes the operating controls and
indicators, the turn-on checkout sequence, and operating
modes of Bipolar Power Supply/Amplifier (BPS/A) models
6826A and 6827A. Local and remote programming opera¬
tions are also described.
3-3 REAR TERMINALS AND AC INPUT
3-4 The Bipolar Power Supply/Amplifier (BPS/A) is
shipped with the rear terminals strapped for local program¬
ming (using front pane! controls) as shown in Figure 3-1.
Remote programming strapping requirements are described
in subsequent paragraphs. The power module contains fuse
FI (2A for 115Vac or 1A for 230Vac) and a slide switch for
connecting 115Vac or 230Vac input power to the instru¬
ment. To turn on the BPS/A, set the LINE switch (item
(T) , Figure 3-2) to ON. The LINE ON indicator (2)
should light. Fuse FI protects the main power supply. At
initial turn-on, an interna! circuit protects any loads con¬
nected to the BPS/A from turn-on transients by shorting
the output terminals and disabling the BPS/A's power out¬
put circuits. This circuit operates similarly at turn-off to
protect any loads from turn-off transients.
3-5 OPERATING CONTROLS AND
INDICATORS
3-6 MODE SWITCH
3-7 The MODE switch @ allows the BPS/A to oper
ate as a power supply, variable gain amplifier, or a fixed gain
amplifier. In the power supply operation, the BPS/A pro¬
vides a variable bipolar dc output voltage dependent upon
the RANGE switch (4) and VOLTAGE control (§)
settings. The dc output voltage ranges are as follows:
3-1