Keithley -
Contents
1. Show a block diagram of your measurement system including all instruments connected whether power is turned on or not Also describe signal source Where is the measurement being performed factory controlled laboratory out of doors etc What power line voltage is used Ambient temperature SE Relative humidity Other Any additional information If special modifications have been made by the user please describe Be sure to include your name and phone number on this service form KEITHLEY Test Instrumentation Group Keithley Instruments Inc 28775 Aurora Road Cleveland Ohio 44139 Printed in the U S A2. 1 Set the Model 247 for proper line voltage operation as specified in paragraph 2 5 2 Connect a ground wire from case ground on rear panel to the measuring system common 3 Set the front panel controls to A Power switch OFF B Polarity switch OFF C Output voltage switch 0 D 10 turn digital dial 000 full counterclockwise 4 Plug the line cord into the power line with a three wire receptacle to maintain proper case ground WARNING 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 5 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 6 Set the Polarity switch to the desired polarity 7 Turn on the power to the instrument With actual load and output voltage allow one hour for warm up 8 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 WARNING Always turn power OFF and verify that the Model 247 s output meter reads 0V DC be fore connecting or removing any equipment External circuits may retain High Voltage af ter the Model 247 has been turned off Dis
3. Sumiyoshi 24 Bldg Room 201 2 24 2 Sumiyoshi cho Naka ku Yokohama 231 81 45 201 2246 Fax 81 45 201 2247 NETHERLANDS Keithley Instruments BV Avelingen West 49 4202 MS Gorinchem Postbus 559 4200 AN Gorinchem s 01830 35333 Fax 01830 30821 SWITZERLAND Keithley Instruments SA Kriesbachstrasse 4 e 8600 D bendorf 01 821 9444 e Fax 01 820 3081 Model 247 High Voltage Supply Instruction Manual 1990 Keithley Instruments Inc Test Instrumentation Group All rights reserved Cleveland Ohio U S A December 1992 Sixth Printing Document Number 31834 Rev F All Keithley 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 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 Institute ANSI states the a shock hazard exists when voltage lev els greater than 30V RMS or 42 4V peak are present A good safet
4. The Voltage switch sets the output voltage in increments of 500V from OV to 2000V Voltage Dial The Voltage dial is a 10 turn digital dial that supplements the Voltage switch setting by up to 1000V 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 NOTE The output voltage is the sum of the Voltage dial and the Voltage switch 2 1 SECTION 2 Operation a a See HAAAY 2 3 REAR PANEL CONNECTORS AND TERMINALS GND The case ground screw GND is to be connected to the measurement system common Output Connector The output connector is a MHV type UG931 U connector It mates with a MHV type UG932 U connector O KEITHLEY 247 HIGH VOLTAGE SUPPLY POWER ON Figure 2 1 Model 247 Front Panel DANGER HIGH VOLTAGE Figure 2 2 Model 247 Rear Panel 2 2 Fuse The line power fuse Slo Blo is rated 1 6A 250V for 90 127V AC operation and 0 8A 250V for 180 254V AC operation Line Voltage Selector The line voltage selector selects the appropriate line voltage 90 127V AC or 180 254V AC Line Plug The recessed line plug accepts a three wire female line plug for line power OUTPUT VOLTAGE soo 1000 1500 D OUTPUT VOLTAOK 14 SUM OF THE DIAL SETTINGS SECTION 2 Operation 2 4 PREPARATION FOR USE Perform the following procedure to prepare the Model 247 for use
5. 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 troland buffer provide a stable 5VDC to the front panel output voltage controls SECTION 4 Maintenance 4 1 INTRODUCTION death if normal safety precautions are not observed 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 WARNING is operating to specifications To prevent a shock hazard remove the line cord and all test leads from the instrument before removing any cover WARNING The procedures in this section are for use E eee 4 2 RECOMMENDED TEST EQUIPMENT perform these procedures unless qualified to do so Many of the steps in this section may expose you to potentially lethal volt The recommended test equipment required to test and ages that could result in personal injury or maintain the Model 247 is listed in Table 4 1 Table 4 1 Recommended Test Equipment Hem Deserption Specifications Manufacturer Model Oscilloscope 10MHz Phillips 3234 Digital Voltmeter 00170 Keit
6. 10 NUS mif T Lini Jin en 2t im 2 5 wee NG ons BERET erat o E nw H ainan ote xa 4304 INdLNO L on Ser PIA it were vetiu triw Pa Teg 6053 G vet 7 Y D kay ne Deos s t se LAA T per e089 RY 93 OL ERI torios LED ERR Xt O A4t OE 3GGNH AO 3UY PPO NGHL PT o ANG KEH O HOLIMS AN GS eno AA Q ANG EtU O FLU O ANS JOHLNOO ANT 0 NUNL OF NG Sty YE NOIL103S FS 8 NOIL03S HOLIMS ALIUV 0d AH rs YBSZNV SUME i das aay tau sr rd tv9860t b eee OOF 80d 3SAIUQO 20 BAINO tO 3AIUQ 26 3AIUG 10 rmt o 82080 veo u AEH3SSY AH EU zz i TSR La anv Fo Gv2t 08 Tes 040 3N 1 z 3 1GVHOVI30 ANIOd LSIL E0Ed 00 God EOE Aoz geo A0LL v9 5S OL IVNUBANI 430 sd H2M0d S KEITHLEY Service Form Model No Serial No Date Name and Telephone No Company List all control settings describe problem and check boxes that apply to problem J Intermittent L Analog output follows display J Particular range or function bad specify LJ IEEE failure LJ Obvious problem on power up LJ Batteries and fuses are OK L Front panel operational L All ranges or functions are bad LJ Checked all cables Display or output check one LA Drifts LI Unable to zero LA Unstable LJ Will not read applied input 1 Overload L Calibration only LI Certificate of calibration required LJ Data required attach any additional sheets as necessary
7. Description if applicable Part Number H D HM ol 5 3 FACTORY SERVICE If the instrument is to be returned to the factory for serv ice please complete the Service Form which follows this section and return it with the instrument Table 5 1 Model 247 Replacement Parts Pai Nobo Printed Circuit Card PCB 100 109641 Printed Circuit Card PCB 300 208329 High Voltage module Power transformer 308028 40152 EDI PK 10 UG 931 U UG 932 U 309206 1 212 G1B60X03 301317 204737 H H Smith 2192 Bridge rectifier HV connector HV Mating connector Meter Power switch Output Voltage switch assembly Polarity switch 5 1 tea 019 o alo Wai 99 OL H 0t kid WOL UO O ow cetu LIGINI ARO Etid ML son 3 1 vassal rt VII 311938 IAN vd ore 2 5 MOU 2 1 090191 820191 9 orient eo i 7 atsa con KH N cote BATO 34 O tid tome T 6192 niy p BANWA 58 O E Gold ana WLI nog LOWED VIAA vere m ka Li ri wara t tata tete S A sez tere wee ore West KEN N81 Lu Wi WALLY 9 2 1 kiadi i A0 etiw sana D wan YK H L YE ISON MING d 6 Hin O Os v otia Xt ooo CLONO ed TY KI oem HE0 a 6 RIM A005 IOF Er 469 T NI NA VOlIOYeYa TW Z mV pe ND NL EANA WGT TR 1 3931200343 36 080810 ASIAN Ms l 333108 2 14 O O t 01f4 wa WO Laer E enan z 1 mat t O J3i A amp er t toad osu A Ri A tret BOLIW
8. REGULATION 0 005 voltage change from no load to full load RIPPLE AND NOISE 3 5mV rms 10mV p p 3kV 6mA 1mV rms 3mV p p 1kV ImA 10Hz 100kHz SETTLING TIME 4 seconds to within 1V with full resistive load OVERLOAD PROTECTION 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 CONNECTOR Rear panel MHV Type UG 931 U POWER 90 125V 180 250V 50 60Hz 130V A DIMENSIONS WEIGHT 483mm wide x89mm high x 273mm deep 19 in x 3V in x 10 in excluding handles Four holes spaced for rack mounting Net weight 5 9kg 13 Ibs ACCESSORIES SUPPLIED Instruction manual UG 932 U mating connector mounting feet for bench operation Specifications subject to change without notice Table of Contents SECTION 1 General Information 1 1 PURPOSE OF EQUIPMENT taena paha ehe In S RR TRR sia RR sds R NET RE necking 12 DESCRIPTION e e RRR x ana KABA S TTT l 13 SPECIFICATIONS ouihuo decent cee Ride wg ux ware ade Ra d e QNSE PRESSE eee ES 14 SAFETY SYMBOLS AND TERMS com asa pack na qe ERE RR reg ee eee Sp dr R 1 5 WARRANTY INFORMATION iced euer em RRR ent e sint TAG APAT RN E RE ERER ae SECTION 2 Operation 2 1 INSTALLATION i234 R Ra RN dd or kd neee ia Re ksd eda ER e E E E ae 2 2 FRONT PANEL CONTROLS AND TERMINALS la nawa K de war REEL ERE 2 3 REAR PANEL CONNECTORS AND TERMINALS
9. SECTION 4 Maintenance Table 4 1 Recommended Test Equipment re 9 c9 9 9 9 9 nan 9 pop o P e 9 4 e e e 9 9 9 v 9 v List of Illustrations SECTION 2 Operation Figure 2 1 Model 247 Front Panel lt lt waaa casei cee bees eee tebe neon eee ee eR Yd eee towers eet Figure 2 2 Model 247 Rear Panel 425 a space EN er ew cw ee es RTE RR RR ES RRR RR dead s Beek ee diua Figure 2 3 Connector and Cable Assembly K reese 4 nora rh hmm sera ree ee Figure 2 4 Photomul plier Circuit oes2usae s esu Rn e KS AGE ALA NAN PLS e E T MEER EE eq Figure 2 5 Resistivity Measurement 22sec leere here ht hn Figure 2 6 Ionization Chamber Circuit na KAG bG debater teres RO RUE RE RR ROS WR E Roe eee SECTION 3 Theory of Operation Figure 3 1 High Voltage Power Supply Block Diagram nn 3 1 SECTION 4 Maintenance Figure 4 1 Model 247 T A auod WE ROO Pa boe odd aries ed deed quan iau SECTION 1 General Information 1 1 PURPOSE OF EQUIPMENT The Model 247 is a regulated precision laboratory high voltage power supply It provides the low noise excel lentlineregulation 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 v
10. fits around the connector see Figure 2 3 6 Assemble as in Figure 2 3 WN WARNING When the High Voltage Output is not in use turn off the power and cover the output con nector with the supplied cover cap SECTION 2 Operation UG 932 U Conn Voltage Rating to 5kV Lass Connector and Cable Assembly Figure 2 3 2 8 APPLICATIONS The following are four examples of typical applications of the Model 247 related to the low current capabilities of electrometers and picoammeters 2 9 1 Application of 247 with Photomultipliers The electron multiplier requires up to 200 volts per stage and may have 10to 14 stages Thus a total supply voltage up to 3000V may 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 actual load and output voltage Figure 2 4 Photomultiplier Circuit 2 8 2 Application of 247 to Resistivity Measurements To find resistivity 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 2 4 tance materials may be measured Flexible materials such as PVC rubber or paper may be tested with the Model 6105 Resistivity
11. high frequency approxi mately 20kHz 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 Assembly H V isolation Tuneable Control Oscillator Amplifier Reference Error Circuit Amplifier High Voltage Power Supply Block Diagram 3 2 CIRCUIT DESCRIPTION The AC input line is converted to the B 36VDC supply and regulated 12V 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 12V consists of a rectifier circuit located on T1 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 SECTION 3 Theory of Operation 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
12. 2 22 2a aaa aman 2 4 PREPARATION FOR USE 25 INPUT POWER 34 35 53 209822 3 Vee Gaede Ue ISP Opapa ed qaae q xad aa cee KANAL 2 6 CURRENT LIMITING paba sro i napa pnpa Pa AG p RISE EE SET beaa ence deans 2 7 HIGH VOLTAGE OUTPUT 2 8 APPLICATIONS sen brauch BAK KGG Chad dees Sepp CR aU do amba APA cholera 2 8 1 Application of 247 with Photomultipliers 4 x eee eee eee eee eee ee 2 8 2 Application of 247 to Resistivity Measurements 2 K rr 2 8 3 Application of 247 with Ionization Chambers uae aga BANA ANA ATE RR EREERPRANA S RES SECTION 3 Theory of Operation 3 1 FUNCTIONAL DESCRIPTION is we GA Sox De ead 97K OO ee Or ES OS OO EK OR OS 3 1 3 2 CIRCUIT DESCRIPTION Wee Chere eee eee BNET 3 1 SECTION 4 Maintenance 41 INTRODUCTION PENA AP Ganka eae PE 42 RECOMMENDED TEST EQUIPMENT 22 2 ee ee ce ee ene ete rl 4 3 PREPARATION FOR MEASUREMENTS 20 02 aaa 4 4 CALIBRATION ADJUSTMENTS ca GERA GA KAKA RR CR do OOO bh AGE BG HUE GG ERA Shee a 4 5 PERFORMANCE TESTS an AG 666 8 obs OSs REOR RATE eee oe ee HE Ree e S 4 6 TROUBLESHOOTING PROCEDURE ee cee aaa SECTION 5 Replaceable Parts 5 1 INTRODUCTION S s vi dien we S E PEN ADIK Y T Gp pP DRE ERE eva atlas abs NGANGA 5 1 52 ORDERING INFORMATION 44232 waa EROR ROIG Sat Sees shee OR EW ao d OR Eee eee WALA 5 1 5 3 FACTORY SERVICE 96204604543 oie0 068056504 DANG ne d pede edd boron a R RER R R d 5 1 List of Tables
13. 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 makes it easy to check for non linearity polarity sensitivity Warning Chassis of test fixture must be connected to a safety earth ground Resistivity Measurement 2 8 3 Application of 247 with lonization 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 Ionization Chamber Circuit Figure 2 6 SECTION 3 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
14. Model 247 High Voltage Supply Instruction Manual TEE 257 ien VOLTA E SUPPI Contains Operating and Servicing Information KEITHLEY WARRANTY Keithley Instruments Inc warrants this product to be free from defects in material and workmanship for a period of 1 year 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 EXPRE
15. SSED 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 KEIT HLEY Test Instrumentation Group Keithley Instruments Inc 28775 Aurora Road lt Cleveland Ohio 44139 e 216 248 0400 e Fax 216 248 6168 CHINA Keithley Instruments Inc Holiday Inn Lido Office Building 404C Beijing China 100004 8610 436 287 1 2860 8610 436 2871 FRANCE Keithley Instruments SARL 3 All e des Garays B P 60 91122 Palaiseau C dex 01 60 11 51 55 e Fax 01 60 11 77 26 GERMANY Keithley Instruments GmbH lt Landsberger Str 65 82110 Germering 089 849307 0 Fax 089 84930759 GREAT BRITAIN Keithley Instruments Ltd The Minster 58 Portman Road Reading Berkshire RG30 1EA 01734 575666 e Fax 01734 596469 ITALY Keithley Instruments SRL Viale S Gimignano 38 20146 Milano 02 48303008 Fax 02 48302274 JAPAN Keithley Instruments Far East KK
16. charge any residual voltage before connect ing or removing any equipment 2 5 INPUT POWER 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 110V setting or 180 254V 220V setting operation The line fuse ratings are as follows Line Keithley Voltage Fuse Rating Part No 90 127VAC 1 6A 250V slow blow FU 96 7 5 x 20mm 180 254VAC 0 8A 250V slow blow FU 96 6 5 x 20mm 2 6 CURRENT LIMITING 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 instructions for the connector are listed below 1 Gently cut through the outer insulation without cut ting the shield Usinga sharp point unravel the shield braid Clean off all traces of graphite Cut the center insulation to the proper length ap proximately 3 8 Cut the center conductor to ap proximately 1 8 5 Solder center conductor to male pin Cut the braid back so it
17. ck on If output voltage can be obtained but the unit does not properly regulate or the front panel control does not op erate properly PCB 100 is probably defective If no output voltage is obtainable test for AC drive to the base of transistor Q1 or Q2 located on the rear of the unit If drive is present the high voltage assembly or transis tors are probably defective Itisrecommended that the unit be returned to the factory for therepair of thehigh voltage assembly Specify model number and serial number in all correspondence with the factory 4 3 SECTION 4 Maintenance R171 R173 R178 R172 Power Transformer R101 Module Polarity Meter Switch Output Voltage Swith Qutput Assembly Dia Figure 4 1 Model 247 Exploded View SECTION 5 Replaceable Parts 5 1 INTRODUCTION Operational spares to support the Model 247 are avail able from the factory It is recommended that common electronic components i e resistors capacitors transis tors etc be purchased from local electronics distribu tors These parts are called out on the schematic diagrams located on the following pages 5 2 ORDERING INFORMATION To place an order or to obtain information concerning re placement parts contact your Keithley representative or the factory Seeinside front cover for addresses When or dering include the following information Instrument Model Number Instrument Serial Number Parts Description Circuit
18. ction Manual If there is a need to exercise the War ranty contact the factory to determine the proper action to be taken NOTE Attempting to repair or tampering with the unit while still under warranty less than 12 months since date of shipment will void the warranty All in warranty repairs should be sent to the factory SECTION 2 Operation 2 1 INSTALLATION 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 Figure 2 1 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 corner 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 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 Polarity Switch The polarity switch sets the output for positive or negative polarity Also it switches the output voltage off CAUTION A two second delay in the center OFF posi tion is required when switching polarity Voltage Switch
19. d stick to which the load resistor is attached Then with the shorting stick connect the load resistor across thehigh 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 10 to the power supply and again observe the change in digital voltmeter reading This change should be less than 0 001 Additional line and load regulation and ripple measure ments may be performed at other voltage levels using the same procedure outlined above This should not usually be necessary Satisfactory test data at maximum output voltage and the full range of voltage control generally in dicate that satisfactory test data will be obtained at all voltage levels However full range testing is performed at the factory on each unit prior to shipment 4 6 TROUBLESHOOTING PROCEDURE A Model 247 High Voltage Power Supply consists of eas ily replaceable plug in printed circuit boards and a main chassis assembly which includes the high voltage cir cuitry The basic troubleshooting procedure consists of determining which of these assemblies is defective Re moval of the top c
20. hley 192 Variable Auto Transformer General Radio 3030 5118 Voltage Divider 1000 to 1 Julie Research HV 10 Load Resistor Clarostat VP 50 k 50k 50M AC Viewing Circuit Power Line Ammeter 1 Valhalla Scientific 2000 4 1 SECTION 4 Maintenance HV T 001 8kV FCI KM9 80 1K Qty Description Resistor 5 6MQ To Scope 1 H Capacitor 001pF at 8kV 1 Neon Lamp NE 2 4 3 PREPARATION FOR MEASUREMENTS Connect the HIGH VOLTAGE OUTPUT 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 Adju
21. oltage 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 Model 247 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 The symbol A on the instrument denotes that the user should refer to the operating instructions The symbol Z on the instrument denotes that 1000V or 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 1 1 SECTION 1 General Information 1 5 WARRANTY INFORMATION The warranty is given on the inside front cover of this In stru
22. over provides access to the printed cir cuit board and high voltage components The printed cir cuit board is secured by four screws to the bottom of the chassis No further disassembly is required for troubleshooting purposes Make sure all test instruments are grounded either to the high voltage connector shield or directly to the chassis prior to the application of input power to the unit The following procedures should then be followed Remove connector cable from P303 on PCB300 see Fig ure 4 1 for location This leaves only the low voltage B and the unregulated 20 volt power supplies operable Turn on the AC line power and measure the DC voltage obtained across R101 See Figure 4 1 for location This SECTION 4 Maintenance voltage should be approximately 41VDC If this voltage differs by more than 1596 the power transformer or PCB100 is probably defective If the B supply is operating properly check for unregu lated 20VDC output accessible across C103 and C131 on PCB100 The voltages should be of equal magnitude to within 5 and within the range of 16 to 24VDC If the magnitude and tracking are not within the range specified this circuitry is probably defective If all of the low voltage power supplies are operating properly turn off input power insert connector to P303 turn all voltage controls to zero follow the PREPARA TION FOR MEASUREMENTS procedure in paragraph 4 3 and turn the line power ba
23. st Potentiometer R172 of PCB 100 see Fig ure 4 1 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 R172 if necessary 4 2 Potentiometer R178 is an Overload Adjustment To cali brate this adjustment set the Model 247 for full load and full voltage 3000V at 6m A by using the load resistor E on theoutput Adjust R178 until the voltage drops off and then back off of R178 approximately 1 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 6m A 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 late
24. y 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 instruments while power is applied to the circuit under test Turn off all power and discharge any capacitors before 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 ona dry insulated surface capable of with standing the voltage being measured Instrumentation and accessories should not be connected to humans The 4 symbol on a Model 247 indicates that 1000V or more may be present on the terminals Refer to the Model 247 Instruction Manual Model 247 High Voltage Power Supply Voltage 0 to 3kV DC Current 6mA DC maximum Polarity Positive or negative with respect to chassis ACCURACY 18 28 C 0 25 of setting 1 5V DC from 1 to 100 of maximum output voltage RESOLUTION Dial graduations of 200mV STABILITY 0 01 of setting hr 40 02 of setting 8 hrs at constant temperature after Y hour warm up TEMPERATURE COEFFICIENT 0 18 C amp 28 50 C 50ppm C LINE REGULATION 0 001 voltage change for 10 line variation LOAD
Download Pdf Manuals
Related Search