Keithley 247 User manual

[phone] | [email protected] | artisantg.com
-~
ARTISAN
®
~I
TECHNOLOGY
GROUP
Your definitive source
for
quality
pre-owned
equipment.
Artisan Technology
Group
Full-service,
independent
repair
center
with
experienced
engineers
and
technicians
on staff.
We
buy
your
excess,
underutilized,
and
idle
equipment
along
with
credit
for
buybacks
and
trade-ins
.
Custom
engineering
so
your
equipment
works
exactly as
you
specify.
•
Critical
and
expedited
services
•
Leasing
/
Rentals/
Demos
• In
stock/
Ready-to-ship
•
!TAR-certified
secure
asset
solutions
Expert
team
ITrust
guarantee
I
100%
satisfaction
All
tr
ademarks,
br
a
nd
names, a
nd
br
a
nd
s a
pp
earing here
in
are
th
e property of
th
e
ir
r
es
pecti
ve
ow
ner
s.
Find the Keithley 247 at our website: Click HERE

Model 247
High Voltage Supply
Instruction Manual
Contains Operating and Servicing Information
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1year from date of
shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries,
diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You will
be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs
will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the origi-
nal warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of
any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leakage, or
problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDI-
RECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND
SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF
SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL
AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.
Test Instrumentation Group, Keithley Instruments, Inc. l 28775 Aurora Road l Cleveland,Ohio 44139 l [phone] *Fax: [phone]
CHINA: Keithley Instruments, Inc. *Holiday InnLido l Office Building 4&4Cl Beijing, China, ICOO l 8610-436-2871/2860 l 8610-436-2871
FRANCE: Keithley Instruments SARL *3All&edes Gamys l B.P.60 l 91122 PalaiseauC&dex*01-60-11-51-55~ Fax: 01-60-H-77-26
GERMANY. Keithley Instruments GmbH l Landsberge.rStr.65.82110 Gennering 0089-849307-O l Fax: [phone]
GREAT BRITAINz Keitbley Instruments, Ltd. l The Minsterl 58 PortmanRoad l Reading, Be&shire RG30 IEA l 01734-575666 l Fax: [phone]
ITALY: Keithley Instruments SRL l Vialc S. Gimignano 38 l 20146 hfilano. 02-48303008 l Fax: [phone]
JAPAN: Keithley Instruments Far East KK l Sumiyoshi 24 Bldg., Room 201 l 2-24-2 Sumiyoshi-cho *Naka-ku, Yokohama 231 l 81-45-201-2246 l Fax: [phone]
NE-S: Keithley Instruments BV. Awlingen West49 l 4202 MS Gorinchem . Postbus559 l 4200 AN Gorinchem l 01830-35333 *Fax: [phone]
SWlTZERUNDz Keithley Instruments SA* Kriesbachstrasse4 l 8600 Diibendorf *01-821-9444 l Fax: [phone]
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Model 247 High Voltage Supply
Instruction Manual
Q 1990, Keithley Instruments, Inc.
Test Instrumentation Group
All rights reserved.
Cleveland, Ohio, U.S.A.
December 1992, Sixth Printing
Document Number: 31834 Rev. F
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

AUKeithIey product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SAFETY PRECAUTIONS
The following safety precautions should be observed before using Model 247 High Voltage Supply.
The Model 247 High Voltage Supply is intended for use by qualified personnel who recognize shock hazards and are
familiar with the safety precautions required to avoid possible injury. Read over the instruction manual carefully before
using the instrument.
Exercise extreme caution when a shock hazard is present. Lethal voltages may be present on the test fixture or the supply
output connector. The American National Standards Jnstitute (ANSI) states the a shock hazard exists when voltage lev-
els greater than3OV RMS or 42.4V peak are present. A good safety practice is to expect that hazardous voltage is present
in any unknown circuit before measuring.
Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.
For maximum safety, do not touch the voltage supply, test fixture, test cables or any other insfnunents while power is
applied to the circuit under test. Turn off all power and discharge any capacitorsbefore connecting or disconnecting
cables or jumpers.
Do not touch any object which could provide a current path to the common side of the circuit under test or power line
(earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of with-
standing the voltage being measured.
Instrumentation and accessories should not be connected to humans.
The L symbol on a Model 247 indicates that 1OOOVor more may be present on the terminals. Refer to the Model 247
Instruction Manual.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Model 247
High Voltage Power Supply
OUTPUT:
Voltage: 0 to 3kV DC
Currentz6mA DC maximum.
Polarity: Positive or negative with respect to chassis.
ACCUI&4CY: (W-28°C): f (0.25% of setting t 1.5V DC) from 1% to 100% of maximum
output voltage.
RESOLUTION: Dial graduations of 200mV.
STABILITY: &O.Ol%of setting/hr.; fo.OZ%of setting/bhrs., at constant temperatureafter
r+hour warm-up.
TEMPEIUTURE COEFFICIENT (W’-18°C& 28”-50°C):sOppm/“C
LINE REGULATIONz 0.001% voltage change for 10%line variation.
LOAD REGULATION: 0.005% voltage change from no load to full load.
RIPPLEANDNOISE:3.5mVrms,lOmVp-p@3kV,6mA;lmV~,3mVp-p@lkV,lmA,
lOHz-1OOkHz
SE’ITLING TIME: 4 seconds to within 1V with full resistive load.
OVERLOAD PROTECTIONr Short circuit proof, arc protected, self restoring.
METER Monitors voltage output.
ENVIRONMENT:
Operating: 0’ to 50°C, 0 to 80% relative humidity up to 35°C
Storage: -40° to 75°C
CONNECTORz Rear panel, MI-IVType LJG931/U.
POWER: 90-125V/180-25OV,50-6OHz,13OVA.
DIMENSIONS,WEIG~:483mmwidex89mmhighx273~deep(l9inx3~/~in.x103/4
in.), excluding handles. Four holes spaced forrack mounting. Net weight5.9kg (13Ibs.).
ACCESSORIES SUPPLIEIX Instruction manual,UG932/U mating connector, mounting
feet for bench operation.
Specifications subject to change without notice.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Table of Contents
SECTION 1 - General Information
1.1 PURPOSEOFEQUIPMENT .................................................... ..I- 1
1.2 DESCRIPTION ................................................................ l-l
1.3 SPECIFICATIONS ............................................................. l-l
1.4 sAFETYsYMEioLsANDTERMs.. ................................................ l- 1
1.5 W~INFoRMATION....................................................l- 2
SECTION 2 - Operation
2.1 INSTALLATION .............................................................. 2-l
2.2 FRONTl?ANELCONTROLSANDTERMlNALS .................................... ..2- 1
2.3 REAR PANEL CONNECTORS AND TERMINALS ..................................... 2-2
2.4 l?REPAlK!JONFORUSE ..................................................... ..2- 3
2.5 INPUTPOWER ............................................................... 2-3
2.6 CURRENTLIMITING ........................................................ ..2- 3
27 HIGH VOLTAGE OUTPUT ...................................................... 2-3
2.8 APPLICATIONS ............................................................... 2-4
2.8.1 Application of 247 wit& Photomultipliers .......................................... 2-4
2.8.2 Application of 247 to Resisfivify Measurements ...................................... 2-4
2.8.3 Application of 247 with Ionization Chambers ....................................... 2-4
SECTION 3 - Theory of Operation
3.1 FUNCTIONALDESCRTMTON .................................................... 3-l
3.2 CIRCUtTDESCIUI’TION ...................................................... ..3- 1
SECTION 4 - Maintenance
4.1 INTRODUcTloN .............................................................. 4-l
4.2 RECOMMENDED TEST EQUIPMENT .............................................. 4-l
4.3 PREPARATION FORMEAS UREMENTS ............................................ 4-2
4.4 CALIBRATION ADJUSTMENTS .................................................. 4-2
4.5 PERFORMANCETESTS ......................................................... 4-2
4.6 TROUJ3LESHOOTlNG PROCEDURE .. f. ........................................... 4-3
SECTION 5 - Replaceable Parts
5.1 INTRODUCTION .............................................................. 5-l
5.2 ORDERINGINFORMATION ..................................................... 5-l
5.3 FACTORYSERVICE............................................................5- 1
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

List of Tables
SECTION 4 - Maintenance
Table 41 Recommended Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

List of Illustrations
SECTION 2 - Operation
Figure 2-1 Model 247 Front Panel ..................................................... 2-2
Figure 2-2 Mode1247RearPanel ...................................................... 2-2
Figure 2-3 Connector and Cable Assembly .............................................. 2-4
Figure 2-4 PhotomultiplierCircuit...................................- ................. 2-4
Figure 2-5 Resistivity Measurement .................................................... 2-4
Figure 2-6 Ionization Chamber Circuit .................................................. 24
SECTION 3 - Theory of Operation
Figure 3-l High Voltage Power Supply Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-l
SECTION 4 - Maintenance
Figure 41 Model 247 Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION1
General Information
1.I PURPOSE OF EQUIPMENT
The Model 247 is a regulated precision laboratory high
voltage power supply. It provides the low noise, excel-
lent line regulation and high stability that are essential for
the most rigid measurement requirements.
1.2 DESCRIPTION
The Model 247 is a precision regulated linear power sup-
ply with a maximum output voltage of 3kV. The units
consist of a DC power supply which converts the AC line
power to a low DC voltage and a DC converter which
generates the high DC output voltage. Low voltage elec-
tronic solid-state circuitry is mounted on the plug-in PCB
100, and the high voltage assembly is fully encapsulated
for reliable, arc-free, operation.
This stable, low noise high voltage power supply features
front panel digital voltage metering and calibrated direct
reading front panel controls, and a polarity selector
switch. The rear panel features a HV output connector
line power plug, fuse, and a voltage selector switch. The
unit is arc and short circuit protected for safe, reliable op-
eration
The unit is fully enclosed and designed to mount in a
standard 19” rack. The unit may also be used in benchtop
applications using the rubber feet supplied.
1.3 SPECIFICATIONS
For Model247 detailed specifications, refer to the specifi-
cations that precede this section.
1.4 SAFETY SYMBOLS AND TERMS
Safety symbols used in this manual are as follows:
Thesymbol ’
Q on the instrument denotes that the user
should refer to the operating instructions.
The symbol on the instrument denotes that 1OOOVor
more may be present on the terminal(s).
The WARNING used in this manual explains dangers
that could result in personal injury or death.
The CAUTION used in this manual explains hazards
that could damage the instrument.
l-l
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION 1
General Information
1.5 WARRANTY INFORMATION NOTE
Attempting to repair or tampering with the
The warranty is given on the inside front cover of this In- unit while still under warranty (less than 12
struction Manual. If there is a need to exercise the War-
ranty, contact the factory to determine the proper action months since date of shipment> will void the
to be taken. warranty. All in-warranty repairs should be
sent to the factory.
l-2
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION2
Operation
2.1 INSTALLATION Polarity Switch -The polarity switch sets the output for
positive or negative polarity. Also, it switches the output
WARNING
This unit outputs hazardous voltage that
could cause injury or death. Do not connect
to line power unless ground (GND) and out-
put high are properly connected.
voltage off.
CAUTION
A two-second delay in the center OFF posi-
tion is required when switching polarity.
Figure 2-l shows the mounting and clearance dimen-
sions as well as the controls and connectors on the front
and rear panels. Rubber feet and screws are supplied
with each unit. For benchtop use, remove the four comer
screws and install the four rubber feet using the new
screws.
2.2 FRONT PANEL CONTROLS AND
TERMINALS
Power Switch -A rocker switch turns the line power on
or off to the entire instrument. The rocker switch has a
built-in pilot lamp that is lit when the power switch is on.
Voltage Switch - The Voltage switch sets the output
voltage in increments of 500V from OVto 2OOOV.
Voltage Dial - The Voltage dial is a 10 turn digital dial
that supplements the Voltage switch setting by up to
1ooov.
WARNING
Before turning the power on to the instru-
ment, make sure the voltage switch and dial
are properly set. Monitor the output on the
meter when the power is on.
Output Meter -The output meter monitors the output
voltage. Meter operation is independent of the AC input
power; therefore, it reads the output at all times.
NOTE
The output voltage is the sum of the Voltage
dial and the Voltage switch.
2-l
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION 2
Operation
2.3 REAR PANEL CONNECTORS AND Fuse -The line power fuse (Slo-Blo) is rated 1.6A, 250V
TERMINALS for 90-127V AC operation and 0.8A, 250V for 180~254V
AC operation.
GND -The case ground screw (GND) is to be connected
to the measurement system common. Line Voltage Selector - The line voltage selector selects
the appropriate line voltage 90-127VAC or MO-254V AC.
Output Connector - The output connector is a h4lW
type UG931/U connector. It mates with a h4HY type
UG932/U connector. Line Plug - The recessed line plug accepts a three-wire
female line plug for line power.
j
Figure2-l. Model 247 Front Panel
Figure 2-2. Model 247 Rear Panel
2-2
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTTON=!
Operafion
2.4 PREPARATION FOR USE
Perform the following procedure to prepare the Model
247 .-tor use:
1.
2.
3.
4.
5.
6.
7.
8.
Set the Model 247 for proper line voltage operation
as specified in paragraph 2.5.
Connect a ground wire from case ground (on rear
panel) to the measuring system common.
Set the front panel controls to:
A. Power switch - OFF
B. Polarity switch - OFF
C. Output voltage switch - 0
D. lOtumdigitaldial- 000 (full counterclockwise)
Plug the line cord into the power line with a three-
wire receptacle to maintain proper case ground.
The line fuse ratings are as follows:
Line
Voltage Fuse Rating
90-127VAC 1.6A, 25OV, slow blow FU-96-7
5x2On-m
180-254VAC O.SA, 25OV, slow blow, Fu-96-6
5x2Omm
WARNING 2.6 CURRENT LIMITING
This unit is equipped with a three-wire
grounded line cord. This must be used with a
three-wire receptacle where the “third wire”
is connected to earth ground, otherwise per-
sonal injury or death may occur.
Connect the output of the Model 247 to the circuit.
Use a properly rated coaxial cable with the supplied
MHV type UG932/U mating connector to insure
good circuit connections and safe operation. Refer to
paragraph 2.6.
Set the Polarity switch to the desired polarity.
Turn on the power to the instrument. With actual
load and output voltage, allow one hour for warm
UP-
Increase the Voltage switch slowly to reach the ap-
proximate desired voltage. Then trim the voltage
with the Voltage dial until the desired voltage level
is obtained.
The Model 247 includes a current limiting circuit that
automatically drops the output voltage to a safe level
when the rated output current is exceeded by 20%. Refer
to the Maximum Current specification when operating
the unit at reduced output voltages or when operating in
a current limit mode for capacitor charging.
2.7 HIGH VOLTAGE OUTPUT
The high voltage output connector is located on the rear
panel (output LO is connected to chassis). A MHV type
UG932/U shielded mating connector is supplied with
each unit. Assembly insinrctions for the connector are
listed below.
WARNING
Always turn power OFF and verify that the
Model 247’s output meter reads OVDC, be-
fore connecting or removing any equipment.
External circuits may retain High Voltage af-
ter the Model 247 has been turned off. Dis-
charge any residual voltage before connect-
ing or removing any equipment.
1.
2.
3.
4.
5.
6.
Gently cut through the outer insulation without cut-
ting the shield.
Using a sharp point, unravel the shield braid.
Clean off all traces of graphite.
Cut the center insulation to the proper length cap-
proximately 3/8”). Cut the center conductor to ap-
protiately l/8”.
Solder center conductor to male pm. Cut the braid
back so it fits around the connector (see Figure 2-3).
Assemble as in Figure 2-3.
2.5 INPUT POWER WARNING
The AC input line voltage required to operate the instru-
ment is 90-127V or 180~254V. The recessed line voltage se-
lector switch on the rear panel selects either 90-127V
(11OV setting) or 180~254V (22OV setting) operation.
Keithley
Part No.
When the High Voltage Output is not in use,
turn off the power and cover the output con-
nector with the supplied cover cap.
2-3
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION 2
-1 )t3/32 UG-932RI Ccnn.
Voltage Rating to 5kV
Figwe 2-3. Connector and Cable Assembly I
2.8 APPLICATIONS
The following are four examples of typical applications
of theMode 247, related to the low current capabilities of
electrometers and picoammeters.
2.8.1 Application of 247 with
Photomultipliers
The electron-multiplier requires up to 200 volts per stage
and may have 10 to 14 stages. Thus, a totalsupply voltage
up to 3OOOVmay be needed. The overall sensitivity or
gain is very responsive to changes in supply voltage. For
this reason the long-term stability of the supply must be
excellent. The specified stability of the Model 247 is valid
after one-hour warm up- Warm up takes one hour with
a&.& load and output voltage.
Figure 2-4. Phofomulfiplier Circuit
2.8.2 Application of 247 to Resistivity
Measurements
To find resistitity of insulating materials, a known volt-
age is applied to a sample of the material. The resulting
current is measured with a picoammeter or electrometer.
With a source voltage of 1000 volts or more, higher resis-
tance materials may be measured. Flexible materials such
as PVC, rubber or paper may be tested with the Model
6105 Resistivity Adapter as shown.
The Model 247 is especially useful since it is low-noise
and well-regulated, allowing the more sensitive elec-
trometer ranges to be used when measuring high quality
insulators. The front panel polarity switch makesit easy
to check for non-linearity (polarity sensitivity).
Warning: Chassis of test
firiure must be connected to
a safety earth ground.
?igure2-S. Resisfivity Measuremenf
2.8.3 Application of 247 with Ionization
Chambers
The electrodes must have a bias voltage of several hun-
dred volts to enable them to collect ions. This voltage
must be very steady since fluctuations would be capaci-
tively coupled to the picoammeter and cause spurious
readings. The excellent line and load stabilities of the
Model 247 easily meet this need,
-------1
CentralElectrode
I
Shield Electrode
------
1Figure 2-6. Ionizdion Chamber Circuif
2-4
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION3
Theory of Operation
3.1 FUNCTIONAL DESCRIPTION
Figure 3-1 is a block diagram of the Model 247. The sche-
matic diagram is located in Section 5, Replaceable Parts.
When reading through the Theory of Operation for the
Model 247, it will be helpful to refer to the schematic dia-
gram-
The circuit uses a DC-DC converter which converts low
voltage DC power to a high voltage DC output. This out-
put voltage is highly regulated and filtered and can be
varied by the front panel controls. The input to the DC-
DC converter is obtained from internal low voltage
power supplies powered by AC line input.
An oscillator determines the high frequency (approxi-
mately 2OkHz) at which all amplification high voltage
transformation, rectification and filtering occurs- The
amplification is a function of a control voltage which per-
forms the function of control and regulation. A sample of
the output voltage is compared against a reference volt-
age in the sensing circuit- The sensing circuit generates
the control voltage to set and maintain a fixed high volt-
age output.
High
Voltage
OUtpUt
H.V.
Isolation
Figure3-1. High VoZtagePower Supply Block Diagram
3.2 CIRCUIT DESCRIPTION
The AC input line is converted to the B+ (36VDC) supply
and regulated kl2V low voltage power supplies. The B+
supply is a filtered full wave rectifier circuit located on
the chassis. The regulated low voltage power supply cir-
cuit (+12VI consists of a rectifier circuit located on Tl and
output regulators located on PCB-100.
The output of the oscillator circuit which is amplified in
the AGC amplifier, is a function of the control voltage de-
veloped at the output of the error amplifier.
3-I
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION 3
Theory ofOperation
The encapsulated high voltage assembly includes a high
voltage transformer, rectifier or multiplier circuits, ripple
filter and sensing circuit. These are all critical custom de-
signed and encapsulated components.
A sample of the high voltage DC output is fed to the out-
put voltage sensing circuit, and is compared to a com-
mand voltage. Output voltage control is obtained by
varying the command voltage fed to the error amplifier.
The error amplifier compares the command voltage and
the signal from the output voltage sense circuit. Any dif-
ferences causes a correction in the gain control of the
AGC amplifier. The command voltage is controlled by
the front panel controls; The reference and reference con-
trol and buffer provide a stable -5VDC to the front panel
output voltage controls.
3-2
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION4
Maintenance
4.1 INTRODUCTION
Section 4 contains information required for the mainte-
nance of Model 247 units. It is organized around the veri-
fication procedure used to determine that the equipment
is operating to specifications.
WARNING
The procedures in this section are for use
only by qualified service personnel. Do not
perform these procedures unless qualified
to do so. Many of the steps in this section
may expose you to potentially lethal volt-
ages that could result in personal injury or
Item
A
B
r
C
D
E
P
G
death if normal safety precautions are not
observed.
WARNING
To prevent a shock hazard, remove the line
cord and all test leads from the instrument
before removing any cover.
4.2 RECOMMENDED TEST EQUIPMENT
The recommended test equipment required to test and
maintain the Model 247 is listed in Table 4-1.
Table 41. Recommended Test Equipment
Description
Oscilloscope
Digital Voltmeter
Variable Auto Transformer
Voltage Divider
Load Resistor
AC Viewing Circuit
Power Line Ammeter
Specifications Manufacturer Model
lOMH2 Phillips 3234
-001% Keithley 192
General Radio 3030-5118
1000 to 1 Julie Research HV-10
- Clarostat VP-50-k-5Ok-50M
.I% Valhalla Scientific 2000
4-l
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

SECTION 4
Maintenance
HV
0 I
4.3 PREPARATION FOR
MEASUREMENTS
Connect the HIGH VOLTAGE OUTPTJT of the Model
247 to the high voltage terminal of the DC voltage di-
vider (D) and to the capacitor input of the AC viewing cir-
cuit (F). The low voltage terminal of the DC divider
should be connected to the digital voltmeter input, and
the AC viewing circuit output connected to the oscillo-
scope input. Make sure that a good ground is connected
to all instruments, viewing circuits and the Model 247.
After the ground has been checked, adequate safety pre-
cautions have been taken, and the output voltage con-
trols set at zero, input power can be applied. The AC in-
put should be applied through the variable autotransfor-
mer, which should be initially set for 115 or 230 volts out-
put, as appropriate.
4.4 CALIBRATION ADJUSTMENTS
WARNING
To prevent a shock hazard, remove the
power cord and all test leads from the Model
247 before removing any cover.
Remove the top cover of the Model 247. Set the Volts
switch to 0. Set the Volts dial to read 1000. Adjust the Ref-
erence Adjust Potentiometer (R172) of PCB 100 (see Fig-
ure 4-l) for an output voltage of 1000 volts.
Set the Volts dial to read 10 (with the Volts switch still at
0). Adjust the Offset Adjust Potentiometer (R171) for an
output voltage of 10 volts. Set all front panel voltage con-
trols for 3000 volt output and readjust the Reference Ad-
just Potentiometer 01172) if necessary.
Potentiometer R178 is an Overload Adjustment. To cali-
brate this adjustment set the Model 247 for full load and
full voltage (3000V at 6mA) by using the load resistor (E)
on the output. Adjust R178 until the voltage drops off and
then back off of R178 approximately l/8 of a turn.
Potentiometer R173 is a Frequency Adjustment. To cali-
brate this adjustment set the Model 247 for full load and
full voltage (3000V at 6mA) by using the load resistor (E)
on the output. Adjust R173 for minimum AC power line
current.
Adjustment is not complete. The following performance
tests are used to determine that the unit meets all of its
specifications.
4.5 PERFORMANCE TESTS
Check to assure that the procedures in paragraph 4.3
have been followed.
NOTE
Performance tests may be performed without
doing the calibration.
Turn the front panel output volts control fully clockwise
until the reading on the digital voltmeter indicates maxi-
mum output from the Model 247.
Connect one end of the high voltage load resistor to
ground and the other end to a shorting stick (1 ft. insu-
lated stick to which the load resistor is attached). Then,
with the shorting stick, connect the load resistor across
the high voltage output and observe the change in output
voltage. During this no load to full load test, the digital
voltmeter reading should not change by more than
0.005%.
With the load connected as above, observe the AC ripple
voltage on the oscilloscope. The ripple should be less
than the specified peak-to-peak ripple under this condi-
tion of full load and maximum output voltage.
Vary the autotransformer to produce an AC line input
change of +lO% to the power supply, and again observe
the change in digital voltmeter reading. This change
should be less than 0.001%.
42
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com