Keithley 2500 Service Manual
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Keithley 2500 Service Manual

Dual photodiode meter
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  • Page 1 T h e t e s t & me a s u r e me n t e q u i p me n t y o u n e e d a t t h e p r i c e y o u w a n t . A l l t e s t I n s t r u me n t s , I n c .
  • Page 2 Model 2500 Dual Photodiode Meter Service Manual Contains Calibrating and Servicing Information...
  • Page 3 AGES 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. Keithley Instruments, Inc. • 28775 Aurora Road • Cleveland, OH 44139 • 440-248-0400 • Fax: 440-248-6168 • http://www.keithley.com BELGIUM: Keithley Instruments B.V.
  • Page 4 Model 2500 Dual Photodiode Meter Service Manual ©2000, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A. First Printing, August 2000 Document Number: 2500-902-01 Rev. A...
  • Page 5 Revision includes a revised copy of this print history page. Revision A (Document Number 2500-902-01) ............. August 2000 All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc. Other brand names are trademarks or registered trademarks of their respective holders.
  • Page 6 As described in the International Electrotechnical Commission (IEC) Standard IEC 664, digital multi- meter measuring circuits (e.g., Keithley Models 175A, 199, 2000, 2001, 2002, and 2010) are Installation Category II. All other instruments’ signal terminals are Installation Category I and must not be connect- ed to mains.
  • Page 7 To maintain protection from electric shock and fire, replacement components in mains circuits, including the power transformer, test leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals, may be used if the rating and type are the same. Other components that are not safety related may be purchased from other suppliers as long as they are equivalent to the original component.

  • Page 8: Table Of Contents

    Table of Contents Performance Verification Introduction ................1-2 Verification test requirements ............. 1-2 Environmental conditions ........... 1-2 Warm-up period ..............1-3 Line power ................1-3 Recommended test equipment ........... 1-4 Verification limits ............... 1-4 Example limits calculation ..........1-5 Restoring factory defaults ............1-5 Performing the verification test procedures .......
  • Page 9 Routine Maintenance Introduction ................3-2 Line voltage selection ..............3-2 Line fuse replacement ..............3-2 Troubleshooting Introduction ................4-2 Safety considerations ..............4-2 Repair considerations ..............4-2 Power-on self test ............... 4-3 Front panel tests ................4-3 KEYS test ................4-3 DISPLAY PATTERNS test ..........
  • Page 10 Using the *OPC command ..........B-10 Generating an SRQ on calibration complete ....B-10 Calibration Program Introduction ................C-2 Computer hardware requirements ..........C-2 Software requirements .............. C-2 Calibration equipment ............... C-2 General program instructions ............ C-3 Program C-1 Model 2500 calibration program ......C-4...
  • Page 12 Channel 1 current calibration connections ......2-16 Figure 2-4 Channel 2 current calibration connections ......2-18 Routine Maintenance Figure 3-1 Model 2500 rear panel ............3-3 Troubleshooting Figure 4-1 Overall block diagram ............4-5 Figure 4-2 Analog circuitry block diagram ..........4-7 Figure 4-3 Power supply block diagram ..........
  • Page 14 List of Tables Performance Verification Table 1-1 Recommended verification equipment ........1-4 Table 1-2 Current measurement verification limits ........ 1-8 Table 1-3 Bias voltage accuracy limits ..........1-12 Calibration Table 2-1 Recommended calibration equipment ........2-4 Table 2-2 Calibration menu ..............2-5 Table 2-3 Front panel calibration summary ...........

  • Page 16: Performance Verification

    Performance Verification...

  • Page 17: Introduction

    Performance Verification Model 2500 Service Manual Introduction Use the procedures in this section to verify that Model 2500 Dual Photodiode Meter accu- racy is within the limits stated in the instrument’s one-year accuracy specifications. Per- form these verification procedures: •...

  • Page 18: Warm-Up Period

    Allow the test equipment to warm up for the minimum time specified by the manufacturer. Line power The Model 2500 requires a line voltage of 100V / 120V / 200V / 240V (depending on rear panel line frequency setting) and a line frequency of 50 or 60Hz. Verification tests must be performed within this range.

  • Page 19: Recommended Test Equipment

    Table 1-1. Keep in mind, however, that test equipment uncertainty will add to the uncertainty of each measurement. Generally, test equipment uncertainty should be at least four times better than corresponding Model 2500 specifications. NOTE The Calibrator/Source listed in Table 1-1 does not quite meet the recommended four times better uncertainty for 19µA to 19mA output values.

  • Page 20: Example Limits Calculation

    As an example of how verification limits are calculated, assume you are testing the 2mA range with a 1.9mA input current. Using the Model 2500 one-year accuracy specification of ±(0.1% of reading + 50nA offset), the calculated reading limits are: Limits = 1.9mA ±...

  • Page 21: Performing The Verification Test Procedures

    With the power off, connect the calibrator to the INPUT CHANNEL 1 triax jack, as shown in Figure 1-2. Turn on the Model 2500 and calibrator, and allow them to warm up for at least one hour. Restore front panel (BENCH) defaults as outlined in “Restoring factory defaults.”...
  • Page 22 Model 2500 Service Manual Performance Verification Press the MSR1 key, then select the Model 2500 2nA range on channel 1 with the RANGE key. Select the calibrator passive amps function, and choose the 2nA range. Set the calibrator output to 1.90000nA, and turn the output on.
  • Page 23 Performance Verification Model 2500 Service Manual Verify that the Model 2500 current reading is within the limits for the 2nA range shown in Table 1-2. Repeat steps 4 through 7 for the 20nA through 20mA ranges. (Use the calibrator active amps mode for the 20mA range.) Repeat steps 4 through 8 for negative input currents of the same magnitude.
  • Page 24 Model 2500 Service Manual Performance Verification Figure 1-2 Connections for channel 2 current verification tests OUTPUT FOR GUARDED OPERATION CONNECT OUTPUT CALIBRATOR COMMON TO D.U.T. COMMON INPUT 200V PEAK OUTPUT 200V INPUT PEAK 100mA PREAMP PEAK PREAMP SOURCE COMMON TRIAX...

  • Page 25: Voltage Bias Accuracy

    VOLTAGE SOURCE OUTPUT CHANNEL 1 jack, and connect DMM INPUT LO to the inner ring (LO) of the INPUT CHANNEL 1 jack.) Turn on the Model 2500 and DMM, and allow them to warm up for at least one hour.
  • Page 26 Model 2500 Service Manual Performance Verification 1-11 Figure 1-3 Connections for channel 1 bias voltage verification tests INPUT LO INPUT HI SENSE INPUT Ω 4 WIRE 350V 1100V PEAK PEAK 2001 MULTIMETER 500V PEAK INPUTS Ω2 Ω4 FREQ TEMP PREV...
  • Page 27 1-12 Performance Verification Model 2500 Service Manual Table 1-3 Bias voltage accuracy limits Bias voltage limits Model 2500 bias range Bias voltage 1 year, 65°F to 82°F (18˚C to 28˚C) 010V 10.000V 9.98 to 10.02V 100V 100.00V 99.65 to 100.35V Repeat the entire procedure for channel 2 (Press SRC2 to select channel 2, and make your connections to the channel 2 INPUT and OUTPUT jacks.

  • Page 28: Calibration

    Calibration...

  • Page 29: Introduction

    Allow the test equipment to warm up for the minimum time specified by the manufacturer. Line power The Model 2500 requires a line voltage of 100V / 120V / 200V / 240V (depending on line voltage setting) at line frequency of 50 or 60Hz. The instrument must be calibrated while operating from a line voltage within this range.

  • Page 30: Calibration Considerations

    • Allow signals to settle before calibrating each point. • Do not connect test equipment to the Model 2500 through a scanner or other switching equipment. • If an error occurs during calibration, the Model 2500 will generate an appropriate error message.

  • Page 31: Calibration Menu

    Table 2-1 does not quite meet the recommended four times better uncertainty for 19µA to 19mA output values. The Model 2500 may not meet factory calibration accuracy specifications on the 20µA to 20mA ranges unless further steps are taken to characterize the corresponding calibra- tor ranges using more accurate equipment.

  • Page 32: Unlocking Calibration

    Model 2500 Service Manual Calibration Table 2-2 Calibration menu Menu selection Description UNLOCK Unlock calibration using password (default: 002500). EXECUTE Execute calibration steps. V-CAL Voltage bias calibration. CHAN-1 Channel 1 voltage bias calibration. CHAN-2 Channel 2 voltage bias calibration. I-CAL Current measurement calibration.

  • Page 33: Unlocking Calibration By Remote

    Calibration Model 2500 Service Manual Unlocking calibration by remote To unlock calibration via remote, send the following command: :CAL:PROT:CODE '<password>' For example, the following command uses the default password: :CAL:PROT:CODE 'KI002500' Changing the password The default password (002500) may be changed from the front panel or via remote as dis- cussed below.

  • Page 34: Resetting The Calibration Password

    From normal display, press MENU, select CAL, and then press ENTER. The unit will display the following: CALIBRATION UNLOCK EXECUTE VIEW-DATES Select VIEW-DATES and then press ENTER. The Model 2500 will display the next and last calibration dates and the calibration count as in the following example: NEXT CAL: 04/15/2001...

  • Page 35: Calibration Errors

    (bit 2) in the status byte. (Use the *STB? query to request the status byte.) Query the instrument for the type of error by using the :SYST:ERR? query. The Model 2500 will respond with the error number and a text message describing the nature of the error. See Appendix B for details.
  • Page 36 Model 2500 Service Manual Calibration Use the EDIT keys to select the letter or number, and use the arrow keys to choose the position. (Press EDIT for letters; for numbers.) Enter the present password on the display. (Front panel default: 002500.) Press ENTER to complete the process.
  • Page 37 OUTPUT CHANNEL 1 jack; connect DMM INPUT LO to the inner shield of the INPUT CHANNEL 1 jack.) Select the DMM DC volts function, and enable auto-range. From normal display. Press the Model 2500 SRC1 key, then set the channel 1 volt- age bias source to the 10V range using the RANGE key.
  • Page 38 Model 2500 Service Manual Calibration 2-11 Using the appropriate RANGE key, select the 100V bias voltage range. Repeat steps 4 through 15 for the 100V bias voltage range. Table 2-4 Voltage bias calibration values Voltage bias range Calibration voltages +10.0000V 0.0000V...
  • Page 39 OUTPUT CHANNEL 2 jack; connect DMM INPUT LO to the inner shield of the INPUT CHANNEL 2 jack.) Select the DMM DC volts function, and enable auto-range. From normal display, press the Model 2500 SRC2 key, then set the channel 2 volt- age bias source to the 10V range using the RANGE key.
  • Page 40 DMM RDG: -10.00000 V , ENTER or EXIT. Note the DMM voltage reading, then use the EDIT keys to adjust the Model 2500 display value to agree with the reading and press ENTER. Press EXIT to return to normal display.
  • Page 41 2-3. Select the calibrator passive V/R amps function. Set the calibrator output to +1.90000nA and turn on the output. Press the Model 2500 MSR1 key, then set channel 1 to the 2nA current range using the RANGE key. Press the MENU key, select CAL, then press ENTER.
  • Page 42 Model 2500 Service Manual Calibration 2-15 Table 2-5 Current calibration values Current range Calibration currents +1.90000nA 0.0000nA -1.90000nA 20nA +19.0000nA 0.0000nA -19.0000nA 200nA +190.000nA 0.000nA -190.000nA 2µA +1.90000µA 0.00000µA -1.90000µA 20µA +19.0000µA 0.0000µA -19.0000µA 200µA +190.000µA 0.000µA -190.000µA +1.90000mA 0.00000mA -1.90000mA...
  • Page 43 2-16 Calibration Model 2500 Service Manual Figure 2-3 Channel 1 current calibration connections OUTPUT FOR GUARDED OPERATION CONNECT OUTPUT CALIBRATOR COMMON TO D.U.T. COMMON INPUT 200V PEAK OUTPUT 200V INPUT PEAK 100mA PREAMP PEAK PREAMP SOURCE COMMON TRIAX AMPS COUL...
  • Page 44 2-4. Select the calibrator passive V/R amps function. Set the calibrator output to +1.90000nA, and turn on the output. Press the Model 2500 MSR2 key, then set channel 2 to the 2nA current range using the RANGE key. Press the MENU key, select CAL, then press ENTER.
  • Page 45 2-18 Calibration Model 2500 Service Manual Figure 2-4 Channel 2 current calibration connections OUTPUT FOR GUARDED OPERATION CONNECT OUTPUT CALIBRATOR COMMON TO D.U.T. COMMON INPUT 200V PEAK OUTPUT 200V INPUT PEAK 100mA PREAMP PEAK PREAMP SOURCE COMMON TRIAX AMPS COUL...

  • Page 46: Remote Calibration

    Model 2500 Service Manual Calibration 2-19 Step 7. Enter calibration dates and save calibration NOTE For temporary calibration without saving new calibration constants, proceed to Step 8. Lock out calibration. From the CALIBRATION menu, select SAVE, and then press ENTER. The unit...

  • Page 47: Remote Calibration Procedure

    With the power off, connect the Model 2500 to the controller IEEE-488 interface or RS-232 port using a shielded interface cable. Turn on the Model 2500 and the test equipment, and allow them to warm up for at least one hour before performing calibration.
  • Page 48 Model 2500 Service Manual Calibration 2-21 Send the following command to unlock calibration: :CAL:PROT:CODE 'KI002500' Table 2-7 summarizes the various calibration steps and associated commands, which are covered in more detail throughout the procedure. Table 2-7 Remote calibration step summary...
  • Page 49 Follow these steps to calibrate the channel 1 voltage bias source. Table 2-8 summarizes channel 1 calibration voltages and commands. Connect the DMM to the Model 2500 channel 1 OUTPUT and INPUT LO termi- nals, as shown in Figure 2-1.
  • Page 50 Follow these steps to calibrate the channel 2 voltage bias source. Table 2-9 summarizes channel 1 calibration voltages and commands. Connect the DMM to the Model 2500 channel 2 OUTPUT and INPUT LO termi- nals, as shown in Figure 2-2.
  • Page 51 2-24 Calibration Model 2500 Service Manual Note and record the DMM reading, and send that value as the parameter for the fol- lowing command: :CAL:PROT:SOUR2 <DMM_Reading> Send the following command to output 0V: :SOUR2:VOLT 0 Note and record the DMM reading, and send that value as the parameter for the fol- lowing command: :CAL:PROT:SOUR2 <DMM_Reading>...
  • Page 52 Model 2500 Service Manual Calibration 2-25 Step 6. Channel 1 current calibration Follow these steps to calibrate channel 1 current measurements. Table 2-10 summarizes channel 1 calibration currents and commands. Table 2-10 Channel 1 calibration currents and commands Current range...
  • Page 53 2-26 Calibration Model 2500 Service Manual Connect the calibrator to the Model 2500 INPUT CHANNEL 1 jack, as shown in Figure 2-3. Select the calibrator passive V/R amps function. Set the output current to 1.90000nA, and turn on the calibrator output.
  • Page 54 Model 2500 Service Manual Calibration 2-27 Repeat steps 3 through 8 for the 20nA to 20mA ranges using Table 2-11 as a guide. Be sure to: • Select the appropriate range using the :SENS2:CURR:RANG <Range> command. • Send the appropriate calibration current values with the :CAL:PROT:SENS2 <Current>...
  • Page 55 2-28 Calibration Model 2500 Service Manual Step 8. Program calibration dates Use following commands to set the calibration date and calibration due date: :CAL:PROT:DATE <yyyy>, <mm>, <dd> (Calibration date) :CAL:PROT:NDUE <yyyy>, <mm>, <dd> (Next calibration due date) Note that the year, month, and date must be separated by commas.

  • Page 56: Routine Maintenance

    Routine Maintenance...

  • Page 57: Line Voltage Selection

    The Model 2500 operates from a line voltage in the range of 100V / 120V / 220V / 240V, ±10% at a frequency of 50 or 60Hz. Before plugging in the unit, make sure the line voltage...
  • Page 58 Model 2500 Service Manual Routine Maintenance Figure 3-1 Model 2500 rear panel Model 2500 WARNING: NO INTERNAL OPERATOR SERVICABLE PARTS, SERVICE BY QUALIFIED PERSONNEL ONLY. RATINGS MAX 100V @ 20mA IEEE-488 COMMON MADE IN (CHANGE IEEE ADDRESS MODE U.S.A. WITH FRONT PANEL MENU)
  • Page 59 Routine Maintenance Model 2500 Service Manual...

  • Page 60: Troubleshooting

    Troubleshooting...

  • Page 61: Introduction

    Model 2500 Service Manual Introduction This section of the manual will assist you in troubleshooting and repairing the Model 2500 Dual Photodiode Meter. Included are self tests, test procedures, troubleshooting tables, and circuit descriptions. Note that disassembly instructions are located in Section 5, and component layout drawings are at the end of Section 6.

  • Page 62: Power-On Self Test

    Model 2500 Service Manual Troubleshooting Power-on self test During the power-on sequence, the Model 2500 will perform a checksum test on its EPROM and test its RAM. If one of these tests fails, the instrument will lock up. Front panel tests There are three front panel tests: one to test the functionality of the front panel keys and two to test the display.

  • Page 63: Char Set Test

    Troubleshooting Model 2500 Service Manual Select DISPLAY-PATTERNS, and press ENTER to start the display test. There are five parts to the display test. Each time a front panel key (except EXIT) is pressed, the next part of the test sequence is selected. The five parts of the test sequence are as follows: •...

  • Page 64: Overall Block Diagram

    Model 2500 Service Manual Troubleshooting Overall block diagram Figure 4-1 shows an overall block diagram of the Model 2500. Circuitry may be divided into two general areas: • Analog circuits — includes measurement circuits such as the I/V converter, mux, and A/D converter, as well as voltage bias circuits.

  • Page 65: Analog Circuits

    Bias voltage circuits Each Model 2500 voltage bias source is a digitally controlled source that can source up to ±100V @ 20mA. Digital control information from the MPU is converted into an equiva- lent analog signal, which is amplified to provide the full ±100V, 20mA output capability.
  • Page 66 Model 2500 Service Manual Troubleshooting Figure 4-2 Analog circuitry block diagram R (Range 7 & 8) R (Range 5 & 6) R (Range 3 & 4) Current Range Switching R (Range 1 & 2) Triax INPUT 20mA Max I/V Converter...

  • Page 67: Power Supply

    Power supply Figure 4-3 shows a block diagram of the Model 2500 power supply system. NOTE There are two identical power supply systems in the Model 2500, one for each channel. Only one power supply is shown in Figure 4-3.

  • Page 68: Digital Circuitry

    Model 2500 Service Manual Troubleshooting Digital circuitry Refer to Figure 4-4 for the following discussion on digital circuitry. The core digital circuitry uses a Motorola 68332 microcontroller running at 20MHz. The memory configuration includes a flash EEPROM and a RAM. Flash ROM support allows internal firmware upgrades using either the serial or GPIB port for downloading new firm-...

  • Page 69: Troubleshooting

    4-10 Troubleshooting Model 2500 Service Manual Display board circuits The display board includes a microcontroller that controls the Vacuum Fluorescent Display (VFD) and interprets key data. The microcontroller has four peripheral I/O ports that are used for the various control and read functions.

  • Page 70: Power Supply Checks

    Model 2500 Service Manual Troubleshooting 4-11 Power supply checks Power supply problems can be checked out using Table 4-2. See “Principles of operation” for circuit theory on the power supply. Table 4-2 Power supply checks Step Item/component* Required condition Remarks Line fuse Check continuity.

  • Page 71: Digital Circuitry Checks

    4-12 Troubleshooting Model 2500 Service Manual Digital circuitry checks Digital circuit problems can be checked out using Table 4-3. See “Principles of operation” for a digital circuit description. Table 4-3 Digital circuitry checks Step Item/component Required condition Remarks Power-on test RAM OK, ROM OK.

  • Page 72: Analog Circuitry Checks

    Model 2500 Service Manual Troubleshooting 4-13 Analog circuitry checks Table 4-4 summarizes analog circuitry checks. Table 4-4 Analog circuitry checks Step Item/component Required condition* Remarks INPUT #1 Apply +20mA Select chan 1 20mA range. TP312 -10V Chan 1 I/V converter output.

  • Page 73: No Comm Link Error

    Locate the firmware ROMs located on the digital section of the mother board. These ROMs are the only IC installed in a socket. (Refer to the 2500-100 compo- nent layout drawing at the end of Section 6 for exact location.)

  • Page 74: Disassembly

    Disassembly...

  • Page 75: Introduction

    Disassembly Model 2500 Service Manual Introduction This section explains how to handle, clean, and disassemble the Model 2500 Dual Photo- diode Meter. Disassembly drawings are located at the end of this section. Handling and cleaning To avoid contaminating PC board traces with body oil or other foreign matter, avoid touching the PC board traces while you are repairing the instrument.

  • Page 76: Static Sensitive Devices

    Use the assembly drawings located at the end of this section to assist you as you disassem- ble and reassemble the Model 2500. Refer to these drawings for information about the Keithley part numbers of most mechanical parts in the unit. Assembly drawings include: •...

  • Page 77: Case Cover Removal

    Disassembly Model 2500 Service Manual Case cover removal WARNING Before removing the case cover, disconnect the line cord and any test leads from the instrument. Follow the steps below to remove the case cover to gain access to internal parts.

  • Page 78: Mother Board Removal

    Model 2500 Service Manual Disassembly Unplug cables: • Unplug the connecting cable at the rear of each input board. • Disconnect the input board connecting cables from the mother board at J301 and J501. Remove input board assembly. Slide the input board assembly forward until the INPUT jacks clear the mounting holes in the rear panel, then remove the assembly.

  • Page 79: Front Panel Disassembly

    Disassembly Model 2500 Service Manual Front panel disassembly Use the following procedure to remove the display board and/or the pushbutton switch pad. Remove the power switch rod. Carefully disconnect the power switch rod from the power switch mounted on the rear panel power module. Slide the rod toward the rear until it clears the access hole in the front panel, then remove the rod.

  • Page 80: Power Transformer Removal

    Model 2500 Service Manual Disassembly Power transformer removal To remove the power transformers, simply remove the screws that secure the transformers to the bottom of the chassis, then remove the transformers. Instrument reassembly WARNING To ensure continued protection against electrical shock, verify that power line ground (green and yellow wire attached to the power mod- ule) is connected to the chassis.
  • Page 81 Disassembly Model 2500 Service Manual...

  • Page 82: Replaceable Parts

    Replaceable Parts...

  • Page 83: Parts Lists

    Model 2500 Dual Photodiode Meter. Parts lists The electrical parts lists for the Model 2500 are listed in the tables at the end of this section. For part numbers to the various mechanical parts and assemblies, use the Miscellaneous parts list and the assembly drawings provided at the end of Section 5.

  • Page 84: Component Layouts

    Model 2500 Service Manual Replaceable Parts Component layouts The component layouts for the circuit boards are provided on the following pages. Draw- ings include: • Mother board — 2500-100 • Display board — 2400-110 • Input board — 2500-120 •...
  • Page 85 Replaceable Parts Model 2500 Service Manual Table 6-1 (cont.) Mother board parts list Keithley Circuit designation Description part no. C394,C396,C594,C596 CAP, .01UF, 10%, 50V, CERAMIC C-491-.01 C397,C597 CAP, 47P, 5%, 100V, CERAMIC C-465-47P C398,C598 CAP, 100UF, 20%, 16V, TANTALUM C-504-100 C406,C407,C606,C607 CAP, 100UF, ±20%, 200V, ALUM ELECT C-498-100...
  • Page 86 Model 2500 Service Manual Replaceable Parts Table 6-1 (cont.) Mother board parts list Keithley Circuit designation Description part no. J301,J305,J501,J505 LATCHING HEADER, FRICTION, CS-724-12 SINGLE ROW K306,K506 RELAY, SURFACE MOUNT RL-188 K307,K308,K507,K508 NON LATCHING RELAY RL-242 L101 FERRITE BEAD CH-91...
  • Page 87 Replaceable Parts Model 2500 Service Manual Table 6-1 (cont.) Mother board parts list Keithley Circuit designation Description part no. R332,R334,R532,R532 RES, 4.75M, 1%, 100MW, THICK FILM R-418-4.75M R336,R339,R536,R539 RES, 10, 10%, 100MW, THICK FILM R-418-10 R342,R343,R345,R346,R542,R543,R545,R546 RES, 20K, 5%, 250MW, METAL FILM...
  • Page 88 Model 2500 Service Manual Replaceable Parts Table 6-1 (cont.) Mother board parts list Keithley Circuit designation Description part no. U120 PROGRAMMED ROM 2500-800* U121 PROGRAMMED ROM 2500-801* U150 64K BIT SERIAL FRAM IC-1381 U154,U161 IC, 2 INPUT NAND GATE, NC7S00...
  • Page 89 HCPL-2631 VR101 DIODE, ZENER 30V BZX84C30 DZ-106-30 VR303,VR304,VR503,VR504 DIODE, ZENER MM524694 TI DZ-113 VR308,VR309,VR508,VR509 DIODE, ZENER, 6.2V MMSZ6V2 DZ-97 VR310,VR510 DIODE DZ-127 Y101 CRYSTAL, FSM327 CR-41 Y301,Y501 OSCILLATOR HIGH SPEED CMOS CR-37 12MHZ *Order current firmware revision. For example, 2500-801A01.
  • Page 90 Model 2500 Service Manual Replaceable Parts Table 6-2 Input board parts list Keithley Circuit designation Description part no. C327 CAP, .01UF, 10%, 200V, CERAMIC C-472-.01 C328,C337 CAP, 1000P, 10%, 100V, CERAMIC C-451-1000P C329 CAP, 33PF, 10%, 100V, CERAMIC C-451-33P C330...
  • Page 91 6-10 Replaceable Parts Model 2500 Service Manual Table 6-3 Power board parts list Keithley Circuit designation Description part no. J1001,J1002,J1003,J1004 CONN, RT ANGLE, MALE MOLEX, .156 CS-715-6 RV101 VARISTOR VR-26 Table 6-4 Display board parts list Keithley Circuit designation Description part no.
  • Page 92 Model 2500 Service Manual Replaceable Parts 6-11 Table 6-5 Miscellaneous parts list Description Keithley part no. BANANA JACK, PUSH-IN RED BJ-14-2 BEZEL, REAR 428-303D CABLE ASSEMBLY CA-239-1A CONDUCTIVE RUBBER SWITCH 2500-315A COVER 2500-317A DISPLAY LENS 2500-311A FOOT 428-319A FOOT, EXTRUDED...
  • Page 93 6-12 Replaceable Parts Model 2500 Service Manual...
  • Page 94 Specifications...
  • Page 95 Specifications The Model 2500 Dual Photodiode Meter can measure and display either photodiode current or optical power for two photodiodes with appropriate user-supplied optical power gain/wavelength calibration factors. Measurement Specifications TEMPERATURE ACCURACY 1, 2 COEFFICIENT DC INPUT MAXIMUM 23°C ±5°C 0°–18°C &...
  • Page 96 Specifications General Typical Noise Floor Measurement Specification TYPICAL NOISE FLOOR RMS (1 STDEV), 100 SAMPLES RANGE 0.01 NPLC 0.1 NPLC 1.0 NPLC 10 NPLC 2.000000 nA 2 pA 1 pA 40 fA 15 fA 20.00000 nA 2 pA 1 pA 40 fA 15 fA 200.0000 nA...

  • Page 97: Accuracy Calculations

    Specifications Model 2500 User’s Manual Accuracy calculations The following information discusses how to calculate accuracy for both current measure- ment and voltage bias functions. Current measurement accuracy Current measurement accuracy is calculated as follows: Accuracy = ±(% of reading + offset) As an example of how to calculate the actual reading limits, assume that you are measur- ing 1mA on the 2mA range.

  • Page 98: Calibration Reference

    Calibration Reference...

  • Page 99: Introduction

    Calibration Reference Model 2500 Service Manual Introduction This appendix contains detailed information on the various Model 2500 Dual Photodiode Meter remote calibration commands, calibration error messages, and methods to detect the end of each calibration step. Section 2 of this manual covers detailed calibration procedures.

  • Page 100: Miscellaneous Commands

    Example Send default code of KI002500. :CAL:PROT:CODE 'KI002500' :COUNT? (:CALibration:PROTected:COUNT?) Purpose To request the number of times the Model 2500 has been calibrated. Format :cal:prot:count? Response Number of times calibrated. Description The :COUNT? query may be used to determine the total number of times the Model 2500 has been calibrated.
  • Page 101 Calibration Reference Model 2500 Service Manual :LOCK (:CALibration:PROTected:LOCK) Purpose To lock out calibration. Format :cal:prot:lock Query :cal:prot:lock? Response Calibration unlocked Calibration locked Description The :LOCK command allows you to lock out calibration after complet- ing the procedure. Thus, :LOCK performs the opposite of sending the password with the :CODE command.
  • Page 102 Model 2500 Service Manual Calibration Reference :DATE (:CALibration:PROTected:DATE) Purpose To program the calibration date. Format :cal:prot:date <year>, <month>, <day> Parameters <year> = 2000 to 2099 <month> = 1 to 12 <day> = 1 to 31 Query :cal:prot:date? Response <year>, <month>, <day>...

  • Page 103: Current Measurement Commands

    Calibration Reference Model 2500 Service Manual Current measurement commands :SENSe (:CALibration:PROTected:SENSe[1]) (:CALibration:PROTected:SENSe2) Purpose To calibrate the active channel 1 or channel 2 current range. Format :cal:prot:sens1 <Cal_current> :cal:prot:sens2 <Cal_current> Parameters <Cal_current> = Within ±10% of positive full-range value 0 ±0.1% of full-range value Within ±10% of negative full-range value...

  • Page 104: Voltage Bias Commands

    Model 2500 Service Manual Calibration Reference Voltage bias commands :SOURce (:CALibration:PROTected:SOURce[1]) (:CALibration:PROTected:SOURce2) Purpose To calibrate the active channel 1 or channel 2 voltage bias range. Format :cal:prot:sour1 <DMM_reading> :cal:prot:sour2 <DMM_reading> Parameters <DMM_reading> = Within ±10% of positive full-range value 0 ±0.1% of full-range value Within ±10% of negative full-range value...

  • Page 105: Detecting Calibration Errors

    Several methods to detect calibration errors are discussed below. Reading the error queue As with other Model 2500 errors, any calibration errors will be reported in the error queue. (You can read the error queue by using the :SYST:ERR? query.)

  • Page 106: Status Byte Eav (Error Available) Bit

    Model 2500 Service Manual Calibration Reference Status byte EAV (Error Available) bit Whenever an error is available in the error queue, the EAV (Error Available) bit (bit 2) of the status byte will be set. Use the *STB? query to obtain the status byte, then test bit 2 to see if it is set.

  • Page 107: Using The *Opc Command

    An IEEE-488 bus SRQ (service request) can be used to detect operation complete instead of repeatedly polling the Model 2500. To use this method, send both *ESE 1 and *SRE 32 to the instrument, then include the *OPC command at the end of each calibration com- mand line, as covered above.

  • Page 108: Calibration Program

    Calibration Program...

  • Page 109: Introduction

    Introduction This appendix includes a calibration program written in Basic to help you in calibrating the Model 2500 Dual Photodiode Meter. Refer to Section 2 for more details on calibration procedures, equipment, and connections. Appendix B covers calibration commands in detail.

  • Page 110: General Program Instructions

    Model 2500 and the multimeter to warm up for at least one hour before performing calibration. Make sure the Model 2500 is set for a primary address of 25. (Use the front panel MENU/COMMUNICATIONS/GPIB selection to check or change the address.) Set the calibrator primary address to 17 and digital multimeter primary address to 16.

  • Page 111: Program C-1 Model 2500 Calibration Program

    Calibration Program Model 2500 Service Manual Program C-1 Model 2500 calibration program ' Model 2500 calibration program for use with Keithley 2001 DMM and ' Model 263 Calibrator/Source ' 2500 address = 25. 2001 address = 16. 263 address = 17 OPEN "IEEE"...
  • Page 112 PRINT #1, "OUTPUT 17;O0X" ' Channel 2 current calibration Range = 2E-09: CalPlus = 1.9E-09: CalMinus = -1.9E-09 PRINT "Connect 263 Calibrator output to 2500 channel 2 INPUT jack." GOSUB KeyCheck PRINT #1, "OUTPUT 17;O1X" FOR I = 1 TO 8 ' Loop for all ranges.
  • Page 113 Calibration Program Model 2500 Service Manual DO: PRINT #1, "SRQ?" ' Request SRQ status. INPUT #2, S ' Input SRQ status byte. LOOP UNTIL S ' Wait for operation complete. PRINT #1, "OUTPUT 25;*ESR?" ' Clear OPC. PRINT #1, "ENTER 25"...
  • Page 114 Index Connections for channel 1 bias voltage ve rification tests 1-11 Connections for channel 1 current verification tests 1-7 Connections for channel 2 bias voltage A/D converter 4-6 verification tests 1-12 Aborting calibration steps 2-8 Connections for channel 2 current verification Accuracy calculations A-4 tests 1-9 Measurement accuracy A-4...
  • Page 115 Analog circuits 4-6 Handling PC boards 5-2 Digital circuitry 4-9 Solder repairs 5-2 Overall block diagram 4-5 Power supply 4-8 Program C-1 Model 2500 calibration Input board removal 5-4 program C-4 Instrument reassembly 5-7 Introduction 1-2 Recommended calibration equipment 2-4...
  • Page 116 Verification limits 1-4 Example limits calculation 1-5 Verification test requirements 1-2 Environmental conditions 1-2 Line power 1-3 Warm-up period 1-3 Viewing calibration dates and calibration count 2-7 Voltage bias accuracy 1-10 Voltage bias calibration values 2-11 Voltage bias commands B-7 DATA B-7 SOURce B-7...
  • Page 118 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. _________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ ❑ Intermittent ❑ Analog output follows display ❑...
  • Page 121 Keithley Instruments, Inc. 28775 Aurora Road Cleveland, Ohio 44139 Printed in the U.S.A.

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