User’s Manual Model SR715 Model SR720 LCR Meters 1290-D Reamwood Avenue Sunnyvale, California 94089 Phone: (408) 744-9040 • Fax: (408) 744-9049 email: info@thinkSRS.com • www.thinkSRS.com Copyright © 1991 by SRS, Inc. All Rights Reserved. Revision 1.
TABLE OF CONTENTS GENERAL INFORMATION Safety and Preparation for Use Specifications Basic Operation Passive Devices Series and Parallel Circuit Models Typical Measurement Setups How the SR715/720 Works Abridged Command List Status Bytes GETTING STARTED SR715/720 Display Keypad Fixture Rear Panel iii v viii viii ix x xi xii xiii 1-1 1-2 1-3 1-5 1-6 2-4 2-4 2-4 2-4 2-4 2-6 2-6 2-6 2-7 2-8 2-8 2-9 2-9 2-10 2-10 2-11 Connecting a Device Radial Leaded Parts Axial Leaded Parts Component Dimensions 2-12 2-1
TABLE OF CONTENTS External Bias Fuse 6-1 Functional Tests Front Panel Test Self Test Output Voltage Resistance Measurement Capacitance Measurement 5-1 5-1 5-2 5-2 5-2 5-2 Error Messages Operations Errors Self-test Errors Calibration Errors 6-2 6-2 6-2 6-4 Performance Tests Frequency Accuracy Amplitude Accuracy Impedance Accuracy Resistance Accuracy Capacitance Accuracy Performance Test Record 5-4 5-4 5-5 5-5 5-5 5-6 5-8 GPIB Problems RS232 Problems 6-4 6-4 Fixture Maintenance Cleaning Removing Lea
SR715/720 LCR METER SAFETY AND PREPARATION FOR USE WARNING Dangerous voltages, capable of causing injury or death, are present in this instrument. Use extreme caution whenever the instrument cover is removed. Do not remove the cover while the unit is plugged into a live outlet. CAUTION BIAS VOLTAGE ON CAPACITORS This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage or if the wrong fuse is installed.
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SR715/720 LCR METER v
SR715/720 LCR METER GENERAL INFORMATION The SR715/720 LCR Meters are multifrequency impedance measuring instruments, capable of measuring resistance, capacitance or inductance over a range of more than 13 orders of magnitude. The SR720 has a basic accuracy of 0.05% and has 5 test frequencies. The SR715 has a basic accuracy of 0.2% and 4 test frequencies.
SR715/720 LCR METER ACCURACY Conditions Basic Accuracy At least 30 minute warm up, 23 °C ± 5 °C. SR715: 0.20% SR720: 0.05% See the Accuracy section for detailed accuracy specifications. The table below summarizes the typical use accuracy. Accuracy better than 1% SR720 0.125 Ω < R < 16 MΩ 2.5 µH < L < 25 kH 1.25 pF < C < 12.8 mF SR715 0.143 Ω < R < 14 MΩ 2.9 µH < L < 22 kH 1.43 pF < C < 11.2 mF better than 5% 21 mΩ < R < 96 MΩ 420 nH < L < 150 kH 0.
SR715/720 LCR METER OPTIONS GPIB / Handler Interface Option 01 provides both an IEEE-488 interface and a Handler interface. IEEE-488 Interface: All instrument functions can be controlled or read over the interface. Handler/Sorter Interface: DB25 male connector provides output lines to indicate binning information and instrument status and an input trigger line. Output lines include 8 Pass Bins, QDR Fail Bin, General Fail Bin, Busy, and Bin Data Available.
SR715/720 LCR METER BASIC OPERATION This section is designed to help the user begin making measurements with the SR715/720 LCR meter and to familiarize them with some of its features. For more information on the different features, see the operations section. The SR715/720 comes with a built in fixture for measuring radial leaded components, like most capacitors, and adapters for measuring axial leaded components, like most resistors.
SR715/720 LCR METER Series and Parallel circuit models Rs in capacitors is often referred to as ESR or equivalent series resistance. It includes things like dielectric absorption in addition to the ohmic losses due to the leads. It is often listed on data sheets for electrolytic capacitors used in switching power supplies. At high frequencies, the ESR is the limiting factor in the performance of the capacitor. component. A low Q indicates a nearly pure resistor. Q varies with frequency.
SR715/720 LCR METER Typical measurement setups The table below lists suggested test conditions for various types of components. This is by no means the only set of conditions for measuring, but is a good general "rule of thumb".
SR715/720 LCR METER How the SR715/720 Works The SR715/720 measures the impedance of a component by measuring the voltage across the part and the current through it. This is done for both the real and imaginary (90° phase shifted) components of the signals. The complex ratio of voltage to current is equal to the complex impedance. The processor calculates the various parameters that are displayed, R, C, L, Q or D.
SR715/720 LCR METER COMMAND LIST VARIABLES i,j x Integers Real Number MEASUREMENT SETUP $STL(?) {i} Set (query) settling time to between i=2 and i=99 milliseconds. AVGM(?) {i} Set (query) averaging on (i=1) or off (i=0). BIAS(?) {i} Set (query) DC bias to internal (i=1), external (i=2), or off (i=0). CIRC(?) {i} Set (query) equivalent circuit to series (i=0) or parallel(i=1). CONV(?) {i} Set (query) constant voltage mode on (i=1) or off (i=0).
SR715/720 LCR METER *STB? {i} SENA(?) {i} STAT? {i} Query Serial Poll status byte. If i is included, only bit i is queried. Set (query) LCR Status Enable register to value i (0-255). Query LCR Status byte. If i is included, only bit i is queried.
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GETTING STARTED SR715/720 LCR METERS This section of the manual provides an overall view of the SR715/720. For detailed operating information on specific features, see the Operating and Programming sections.
GETTING STARTED DISPLAY the auto parameter mode. The % LED indicates that the measurement is displayed as a relative deviation from an entered nominal value. Units are indicated by the LEDs located between the two displays: Ω, kΩ, MΩ, µH, mH, H, pF, nF or µF. The minor parameter is dimensionless (Q and D) or has the units of Ohms for resistance, unless the kΩ LED on the right is on. Status information (REM, ACT and ERR) is shown to the right of the minor parameter.
GETTING STARTED KEYPAD The keypad is used to select measurement conditions and to enter values. LEDs indicate the actual measurement conditions. BIAS [Internal] selects a 2.0 VDC internal bias. [External] selects an external bias source. Pressing the active key ([Internal] when internal bias is already selected or [External] when external is selected) turns the bias off. PARAMETER The [R+Q], [L+Q], [C+D], [C+R], and [AUTO] keys select the parameter being measured.
GETTING STARTED mode. The range can also be entered with the numeric keys in the entry display. NUMERIC KEYS [0]..[9], [.], [+/-] The numeric keys enter parameters and are only active when the unit is in the entry display. EQUIV CIRCUIT The [Equiv Circuit] key selects between a series or parallel equivalent circuit model of the component being measured. STORE and RECALL The unit can store up to 9 complete instrument setups in non-volatile memory.
GETTING STARTED FIXTURE Axial leaded devices (leads at opposite ends) require the use of the axial fixture adapters. A versatile test fixture is provided with the SR715/720 that provides a 4 wire Kelvin connection to most types of leaded devices. (A Kelvin connection uses two wires to carry the test current to and from the device and two independent wires to sense the voltage across the device.) This prevents the voltage drop in the current carrying wires from affecting the voltage measurement.
GETTING STARTED REAR PANEL SW1 These switches set baud rate, parity and word length for the RS232 interface. See the programming section for details on setting the interface. POWER ENTRY MODULE The Power Entry Module is used to fuse the line power, select the input voltage, and filter high frequency electrical noise. POWER SWITCH The power switch is located on the rear right side of the unit. Depressing the front side of the switch turns the unit on.
OPERATION DISPLAY The SR715/720 displays both major and minor parameters simultaneously. In addition to the parameter selection, the display type may also be specified. This allows results to be shown in engineering units, deviation from a specified nominal value, or binned for sorting purposes. The display also shows values entered from the keyboard while specifying the nominal value or bin limits. The status LED's indicate remote programming status information.
OPERATION SERIES and PARALLEL EQUIVALENT CIRCUITS Any non-ideal component can be represented as a resistive component either in series or in parallel with a reactive component. Depending upon the characteristics of the component and the measurement frequency, either the series or parallel model will be the more accurate model. The more ideal a component is, the less the two models differ. However, as Q for inductors decreases towards 10 and Q for resistors or D for capacitors increases towards 0.
OPERATION ENTRY The ENTRY display allows entry of nominal values, measurement conditions, and calibration data. To view this display, press the [Display] key until the ENTRY LED is on. If an out of range or incorrect value is entered, the unit will beep and display 'rAnGE Error' (range error) and not accept the value. The ENTRY display is enabled under all conditions. BINS The BINS display shows the bin number that a component falls into when binning is enabled.
OPERATION TEST CONDITIONS DEFAULT CONDITIONS If the back space key [<-] is held down while turning on the unit, it will be set to the default setup shown below Any user calibrations are lost and factory calibrations are used. Using [Recall] [0] [ENTER] will set the unit to the conditions below without disturbing any user calibration values. Parameter Frequency Drive Voltage Bias Measurement Rate Averaging Range Hold Equivalent Circuit Display Trigger Mode Binning AUTO 1kHz 1.
OPERATION been programmed with the vernier setting, none of the primary drive voltage LEDs will be on. To return to the primary output levels, press the [Select] key. The output voltage will be increased to the next highest primary level. The output voltage is applied to the device under test through a source impedance, thus, the voltage across the device is always less than or equal to the output voltage. The different source impedances are 25 Ω (R3), 400 Ω (R2), 6.
OPERATION capacitors (test voltage = 0.5 Vrms). In these cases, use the vernier setting to obtain the exact voltage required. In general use the largest voltage possible for the best signal to noise ratio and accuracy. RANGE The SR715/720 has 4 measurement ranges (0-3). The range may be selected manually or the unit can autorange. The table below specifies the impedance ranges for each of the measurement ranges. Each of the four ranges has source impedance of approximately the mid-scale impedance.
OPERATION autorange to range 0 (or range 1 for 100 kHz) and then autorange back to the appropriate range when a part is inserted in the fixture. Range holding is helpful if measurement speed is a concern or if a number of parts with similar values are being measured. There are two ways to range hold. The present measurement range can be held by simply pressing the [Range Hold] key. The LED above the [Range Hold] key indicates that the unit is in range hold.
OPERATION Range Change Points When Autoranging Ranging To Lower Impedances Impledance Range Change 2 to 3 Z < 315 Ω 1 to 2 Z <5.04 kΩ 0 to 1 Z < 78.8 kΩ Ranging To Higher Impedances Range Change Impledance 3 to 2 Z > 400 Ω 2 to 1 Z > 6.4 kΩ 1 to 0 Z > 100 kΩ Under certain conditions the 'ovEr LoAd' message will be displayed. This normally occurs when the unit is in constant voltage with the range hold on. To correct this, simply change to a higher impedance range, or autorange.
OPERATION EXTERNAL BIAS The SR715/720 has rear panel connections to allow an external bias voltage of up to +40VDC to be applied across the DUT. This supply must be floating (neither side connected to ground) and must be current limited to less than 250 mA. A linear supply is recommended (vs. switching supply). The supply should be well filtered, to remove ripple from the bias voltage. Connections to the bias supply are made on the rear panel with two banana jacks.
OPERATION where Ts = settling time, Ni = number of test frequency cycles used in the measurement, f = test frequency, Tdi = deintegration time, Trs = resync time, Td = delay time, Nm = number of submeasurements per measurement, and T calc = calculation time. Tdi, Td and Tcalc are constants, Trs and f are set by the measurement frequency. Ni and Nm are determined by the measurement rate and Ts set by the user. See the table below for the appropriate values.
OPERATION whenever the unit is triggered. In the triggered mode the unit will make a single measurement per trigger. STORE and RECALL [Store] and [Recall] allow nine complete instrument setups to be saved in non-volatile memory. All the test conditions, including binning configuration and open and short circuit compensation are saved. Store To store a setup, press the [Store] key, which will display the 'StorE' message in the display. Press the number of the stored setting ([1] - [9]) and the [ENTER] key.
OPERATION CONNECTING A DEVICE The SR715/720 has a built in Kelvin fixture for measuring radial leaded components and adapters for measuring axial leaded components. The fixture provides a 4-wire Kelvin connection to the device under test to minimize stray impedances that cause measurement errors. Most components will fit into this fixture, thus eliminating the need for special fixtures.
OPERATION COMPONENT DIMENSIONS The radial fixture can accommodate components with a lead spacing from 0.2" (5mm) up to 3.8" (96.5mm) with a minimum lead length of 0.16" (4mm). The axial lead adapter can accommodate parts with a maximum body length of 2.7" (68.6mm) and a maximum diameter of 1.8" (45.7mm). The closest the adapters can get is 0.12" (3.0mm). The minimum lead length (of each lead) is 0.25" (6.4mm). However the minimum length of the part and lead combined is 0.7" (17.8mm). See the diagrams below.
OPERATION KELVIN CLIPS Kelvin Clips provide a simple means to measure large or unusually sized parts. They can connect to any component lead up to 0.3" (7.6mm) in diameter. When connecting the Kelvin Clips to a device, remember that the red lead denotes the "+" side of the fixture if any biased measurements are made. Connect one clip to each side of the component and perform the measurement. Whenever the fixture configuration is changed, be sure to perform open and short circuit calibration.
OPERATION marked. The side with the silkscreen is the positive side.) To make a measurement, pick up the component with the SMD tweezers so that the metallized ends of the parts contact the tips of the tweezers. The tips can be replaced if they wear out or break. See the maintenance section for details on changing them. BNC ADAPTER The BNC Adapter Set connects the SR715/720 to other test equipment, switching networks, or remote test fixtures.
OPERATION OPEN and SHORT CIRCUIT OR NULL CALIBRATION Compensation of stray impedances is performed by open and short circuit or fixture null calibration. This corrects for lead impedance, and fixture, cable and other stray capacitance. Null calibration corrects for all frequencies and all ranges - it is not necessary to re-calibrate for changes in frequency. Null calibration should be performed after any change in fixture configuration or for changes in the drive amplitude.
OPERATION separation as it will be when making measurements. Again keep hands or other objects away from the clips while performing null cal. See the illustration above. SMD TWEEZERS SMD tweezers present a challenge to calibrate accurately, since their position can vary and the operators hands are always present when making measurements. Use a piece of copper (shorting block) about the same dimensions as the devices to be measured, as the shorting wire. DO NOT just touch the tips together.
OPERATION BINNING The SR715/720 has built in features to aid in component sorting. This is especially useful for production testing, incoming inspection, device matching or tests where multiple devices of similar value must be measured. The binning feature simplifies parts sorting by eliminating the need to read the major and minor parameters and then deciding what to do with the part.
OPERATION Binning data can be entered manually using the [Bin#], [Nominal] and [Limit] keys, or over the RS232 or optional GPIB interface. A bin is defined by a bin number, with a nominal value and upper and lower limits (in percent). If a nominal value is not entered for a bin, it will take the nominal value of the next lower bin. Bin 0 is the exception. If bin 0 doesn't have a nominal value and limits, all parts will fail. Parts that fall into more than one bin are assigned to the lower numbered bin.
OPERATION VALUES FOR FAIL BINS (8 & 9) ENABLE BINNING To set the QDR limit value, select bin 8 (using the [Bin#] [8] [ENTER] keys) and press the [Nominal] key. This will display the present QDR limit, or '-----', in the right display and turn on the NOM LED. Input the value with the numeric keys and press the [ENTER] key. Resistors for the C+R mode are entered in Ω (the allowable range of resistance values is only 0 to 99999 Ω, so no kΩ or MΩ key is needed). There are no limits for the QDR bin.
OPERATION Binning Worksheet Date: Nominal value of component: Tolerance to be sorted to: Entered by: Type of binning: bin # __________ ______________________ ______________________ _______________________________________ Pass/Fail nom Nested Sequential +lim -lim xxxx xxxx xxxx xxxx 0 1 2 3 4 5 6 7 8 9 xxxx 2-21
OPERATION Option 01: GPIB/Handler Interface GPIB Interface: Detailed information on the GPIB interface and programming examples are available in the remote programming section. Handler Interface: Introduction The handler interface for the SR720/715 allows the unit to be operated with external hardware to measure and physically sort components. Data lines for ten sorting bins are provided, as well as control lines (-START, BUSY, -BDA) to coordinate measurements.
OPERATION Mechanical Description: The handler interface is part of the Option 01 GPIB/Handler board and is accessed via a 25 pin male connector on the rear of the SR720/715. A DB25 female connector, metal housing, and plastic sheath have been provided to simplify construction of a cable to the external handler.
ACCURACY DETAILED ACCURACY SPECIFICATION GUIDE CONDITIONS The following conditions must be met for the unit to meet its accuracy specifications 1) 2) 3) 4) 5) Warm up time: > 30 minutes Temperature: 23 ± 5 °C Fixture: Built in Open & Short Circuit Calibration have been performed D < 0.1 for Capacitance Measurements Q < 0.
ACCURACY IMPEDANCE ACCURACY Accuracy of Z = ± [A x Ki x Kv + (Kh + Kl) x 100] % A = Ki = Kv = Kh, Kl = Basic Impedance Accuracy Factor from graph on next page. If the unit is in the constant voltage (CV) mode, double the basic accuracy factor. Integration Time Factor (see Ki Table below) Drive Voltage Error Factor (see Kv Table below) Extreme Range Error Term (see Kh,Kl Table below) Ki Table Meas Rate slow,med fast fast Kh & Kl Table Frequency Zm all 100 Hz-1 kHz 6.
ACCURACY 3-3
ACCURACY R + Q ACCURACY Accuracy of R = ± [A x Ki x Kv + (Kh + Kl) x 100] % A = Ki = Kv = Kh, Kl = Basic Resistance Accuracy Factor from graph. For |Q| > 0.1, multiply the basic accuracy factor by (1 + |Q|). If the unit is in the constant voltage (CV) mode, double the basic accuracy factor. Integration Time Factor (see Ki Table below) Voltage Error Factor (see Kv table below). Extreme Range Error Term (see Kh, Kl table below).
ACCURACY L + Q ACCURACY Accuracy of L = ± [A x Ki x Kv + (Kh + Kl) x 100] % A = Ki = Kv = Kh, Kl = Basic Inductance Accuracy Factor from graph. For Q < 10, multiply the basic accuracy factor by (1 + 1/Q). If the unit is in the constant voltage (CV) mode, double the basic accuracy factor. Integration Time Factor (see Ki Table below) Voltage Error Factor (see Kv table below). Extreme Range Error Term (see Kh, Kl table below).
ACCURACY C + D ACCURACY Accuracy of C = ± [A x Ki x Kv + (Kh + Kl) x 100] % A = Ki = Kv = Kh, Kl = Basic Capacitance Accuracy Factor from graph. For D > 0.1, multiply the basic accuracy factor by (1 + D). If the unit is in the constant voltage (CV) mode or under internal or external bias, double the basic accuracy factor. Integration Time Factor (see Ki Table below) Voltage Error Factor (see Kv table below). Extreme Range Error Term (see Kh, Kl table below).
ACCURACY C + R ACCURACY Accuracy of C = ± [A x Ki x Kv + (Kh + Kl) x 100] % A = Ki = Kv = Kh, Kl = Ki Table Basic Capacitance Accuracy Factor from graph on page 4-6. If the unit is in the constant voltage (CV) mode, or under internal or external bias, double the basic accuracy factor. Integration Time Factor (see Ki Table below) Voltage Error Factor (see Kv table below). Extreme Range Error Term (see Kh, Kl table below).
ACCURACY Accuracy when Holding a non-optimal Range When a component is measured outside of its nominal range (in range hold), the accuracy of the measurement is reduced. The nominal ranges are defined as approximately four times above and below the nominal impedance value. 100kHz values apply to the SR720 only. Range R3 R2 R1 R0 100Hz - 10kHz Nominal Impedance Range 6.25 Ω - 100 Ω 100 Ω - 1.6 kΩ 1.6 kΩ - 25.6 kΩ 25.
REMOTE PROGRAMMING INTRODUCTION bit3 The SR715 / SR720 LCR meters may be remotely programmed via either the RS232 or GPIB (IEEE488) interfaces. Any computer supporting either of these interfaces may be used with the SR715/720. Both interfaces are simultaneously active. The SR715/720 will respond to commands from either interface and return answers to the interface from which the command came. All front and rear panel features (except power) may be controlled.
REMOTE PROGRAMMING Similarly, the SR715/720 has a 256 character output buffer to store output until the host computer is ready to receive it. If the output buffer fills up it is cleared and an error reported. The GPIB output buffer may be cleared by using the Device Clear universal command. PROGRAMMING ERRORS The SR715/720 reports two types of errors that may occur during command execution: command errors and execution errors. Command errors are errors in the command syntax.
REMOTE PROGRAMMING DETAILED COMMAND LIST The four letter mnemonic in each command sequence specifies the command. The rest of the sequence consists of parameters. Multiple parameters are separated by commas. Parameters shown in {} are optional or may be queried while those not in {} are required. Commands that may be queried have a question mark ? in parentheses (?) after the mnemonic. Commands that may ONLY be queried have a ? after the mnemonic. Commands that MAY NOT be queried have no ?.
REMOTE PROGRAMMING RNGH(?) {i} The RNGH command disables (i=0) and enables (i=1) range hold. When range hold is disabled the SR715/720 will autorange. The RNGH? query returns the range hold status. VOLT(?) {x} The VOLT command sets the drive voltage to x volts. x may range from 0.1 V to 1.0 V and is rounded to the nearest 0.05 V. The VOLT? query returns the drive voltage.
REMOTE PROGRAMMING Byte 2 Character 0,1,2,3 Meaning The range on which this measurement was taken. 3 R,L,C The major parameter type if querying the major value. The minor parameter type if querying the minor value. Q,D,R 4-N value The measurement value in exponential notation. If the measurement is invalid, overloaded, or out of range 9.9999E20 is returned. The units of the value are Ohms for R's, Henrys for L's, Farads for C's, and percent for percent deviation.
REMOTE PROGRAMMING Concise Binary The same format as verbose binary except that the status byte (byte 3) is not sent. Note: When using the RS232 interface, the SR715/720 must be set to 8 data bits if the binary data output formats are to be used. XALL? The XALL? query returns the value of the major parameter, minor parameter, and bin number. The three values are returned in the format set by the OUTF command. The 3 responses are separated by commas in the ASCII formats.
REMOTE PROGRAMMING SR715/720 will use the nominal value from the next lowest numbered bin with a non-zero nominal value (several bins can have the same nominal value without entering the value for each bin). The lowest numbered active bin must have its nominal value set. Bin 0 must always be set for binning to be enabled. The BNOM? i query returns the nominal value for bin i. SETUP and CONTROL COMMANDS *IDN? The *IDN? common query returns the SR715/720's device configuration.
REMOTE PROGRAMMING enable registers maintain their values at power down. This allows the production of a service request at power up. *SRE (?) {i} The *SRE i command sets the serial poll enable register to the decimal value i (0-255). The *SRE? query returns the value (0-255) of the serial poll enable register. *STB? {i} The *STB? command queries the value of the serial poll byte. The value is returned as a decimal number from 0 to 255. The *STB? i command queries the value (0 or 1) of bit i (0-7).
REMOTE PROGRAMMING 8 9 Instrumentation Amp Error. The input instrumentation amplifier failed its test. Output Error. The output impedance selector failed its test. This error may occur if there is a part in the fixture when the test is executed. $CBT(?) i {,j} The $CBT command sets amplitude calbyte i to the value j. i may range from 0 to 94, and j from 0 to 255. $CFT(?) i {,x} The $CFT command sets floating point calbyte i to the floating point value x.
REMOTE PROGRAMMING STATUS BYTE DEFINITIONS The SR715/720 reports on its status by means of three status bytes: the serial poll byte, the standard status byte, and the LCR status byte. On power on the SR715/720 may either clear all of its status enable registers or maintain them in the state they were in on power down. The action taken is set by the *PSC command and allows things such as SRQ on power up . SERIAL POLL STATUS BYTE bit name usage 0 Ready The SR7XX is ready to perform a measurement.
REMOTE PROGRAMMING STANDARD EVENT STATUS BYTE bit name usage 0 OPC Set by the OPC command when all measurements are complete 1 unused 2 Query Error 3 unused 4 Execution err Set by an out of range parameter, or non-completion of some command due a condition such as an incorrect operating mode. 5 Command err Set by a command syntax error, or unrecognized command 6 URQ Set by any key press 7 PON Set by power on Set on output queue overflow (Too many responses waiting to be transmitted.
REMOTE PROGRAMMING EXAMPLE PROGRAM 1 Using Microsoft C with the National Instruments GPIB card on the IBM PC. To successfully interface the SR715/720 to a PC via the GPIB interface, the instrument, interface card, and interface drivers must all be configured properly. To configure the SR715/720, the GPIB address must be set using the switches SW2 on the rear panel. Make sure that you follow all the instructions for installing the GPIB card.
REMOTE PROGRAMMING exit (0); } ibwrt (lcr, "*RST", 4L); /* reset LCR meter */ ibwrt (lcr, "MMOD1;PMOD3;FREQ0", 17L); /* set triggered mode, measure C+D, Freq = 100 Hz */ ibwrt (lcr, "outf1", 5L); /* concise ASCII output format */ ibwrt (lcr, "BIAS1", 5L); ibwrt (lcr, "STRT;*WAI;XALL?", 15L); /* turn internal bias on - it may be necessary to wait for the capacitor to charge up here when measuring large capacitors */ /* take a measurement, wait until finished, and get back the data.
REMOTE PROGRAMMING EXAMPLE PROGRAM 2 Using Microsoft C with the Capital Equipment Corp. (CEC) GPIB card on the IBM PC. To successfully interface the SR715/720 to a PC via the GPIB interface, the instrument, interface card, and interface drivers must all be configured properly. To configure the SR715/720, the GPIB address must be set using the switches SW2 on the rear panel. Make sure that you follow all the instructions for installing the GPIB card.
REMOTE PROGRAMMING TxGpib (sr720,"OUTF2"); /* verbose binary output */ TxGpib (sr720,"STRT;*WAI;XALL?"); /* trigger a measurement, wait until it's over, then ask for results */ /* make LCR a GPIB talker */ MakeTalk (sr720); count = 15; rarray (&status, &length, &count, data, &seg); /* read output into array data[] */ /* Check the programming section of the SR720 for detailed information on binary return formats.
REMOTE PROGRAMMING char cmd[25]; sprintf (cmd, "UNT UNL MLA TALK %d", address); /* make the talk command string */ transmit (&status, cmd); /* send the talk command string */ StatCheck (address); /* check interface status */ } /* ********************************************************************* */ void TxGpib (int address,char *command) /* transmit command to address */ { char t_string[150]; int result; result = sprintf (t_string, "UNT UNL MTA LISTEN %d DATA '%s' END", address, command); transmit (&stat
REMOTE PROGRAMMING EXAMPLE PROGRAM 3 Using Microsoft C with the Capital Equipment Corp. (CEC) GPIB card on the IBM PC. To successfully interface the SR715/720 to a PC via the GPIB interface, the instrument, interface card, and interface drivers must all be configured properly. To configure the SR715/720, the GPIB address must be set using the switches SW2 on the rear panel. Make sure that you follow all the instructions for installing the GPIB card.
REMOTE PROGRAMMING void main(void) { int i, b; double rmeas, q; char string[80]; InitGpib(); TxGpib (lcr, "*RST;MMOD1;PMOD1;BCLR"); /* init GPIB controller */ /* reset LCR, triggered mode, measure R and Q, clear all bins */ /* set up the bins */ Clear(); /* clear screen */ printf ("Bin values for the LCR:\n\n"); printf (" Bin # Nominal value Tolerances\n"); for (i=0;i<8;i++) { /* send nominal bin value, upper and lower limits to LCR */ sprintf (string, "BNOM%d,%lf;BLIM0,%d,%lf;BLIM1,%d,%lf\n", i, nom[i],
REMOTE PROGRAMMING } printf ("bin 0 1 printf (" "); for (i=0; i<10; i++) printf("%d printf("\n"); } 2 3 4 5 6 7 QDR Fail\n"); ", bin[i]); /* ************************************************************************ */ void InitGpib (void) /* initialize the CEC GPIB card as controller */ { int my_address, system_controller,seg; /* Find the CEC card address */ for (seg=0x4000;seg<0xF000;seg+=0x400) { if ((peek(seg,50) == 'C') && (peek(seg,51) == 'E') && (peek(seg,52) == 'C'))break; } if (pc488_seg(s
REMOTE PROGRAMMING do { ch = getch (); if ((ch == 'q')||(ch =='Q')) { flushall(); exit(0); } } while(ch != ' '); Erase(25,1); } /* ********************************************************************* */ void Erase (int row, int num) /* Erase num rows starting at row (requires ansi.
REMOTE PROGRAMMING EXAMPLE PROGRAM 4 IBM PC, IBM BASIC using the RS232 interface In this example, the IBM PC serial port COM1: is used at 9600 baud. Configure the SR715/720 to 9600 baud, 8 bits, no parity before running the program. The RS232 configuration is set using switch SW1 on the rear panel.
PERFORMANCE TESTS PERFORMANCE VERIFICATION The performance verification procedures in this section test and verify the performance of the SR715/720 and compare it to the specifications listed at the beginning of this manual. The first set of tests verify the basic functionality of the unit. The second set of tests verify the critical specifications of the SR715/720. The results of each section can be recorded on the test sheet located at the end of this section.
PERFORMANCE TESTS 2. Self Tests The internal self tests verify the functionality of the SR715/720. 1) Turn on the unit. The ROM firmware version and serial number will be displayed for about 3 seconds. Next the message 'tESt.....' will be displayed while the unit performs its self tests. After the tests are completed the unit should display 'tESt PASS' to indicate that the tests were successful. If not, an error message will appear. See the TROUBLESHOOTING section for a description of the error messages.
PERFORMANCE TESTS 5. Capacitance Measurement This verifies that the SR715/720 is able to measure components at different frequencies. The limits of the readings are the same as before (± [component tolerance + meter tolerance]). 1) If the fixture configuration has been changed, perform open and short circuit calibration. 2) Set the SR715/720 to C+D, parallel, 1 kHz. 3) Install the 22 nF capacitor. Verify that the unit reads within 1.10% (SR720) or 1.25% (SR715). Verify that D is below .0001.
PERFORMANCE TESTS PERFORMANCE TESTS These tests are intended to measure the SR715/720's conformance with its published specifications. These test results, along with the results of the functional tests, can be recorded on the test sheet at the end of this section.
PERFORMANCE TESTS 2. Amplitude Accuracy This test measures the amplitude accuracy of the drive output. It should be within 2.0% of the nominal value for all of the amplitude settings. 1) Connect the AC/DC volt meter across the two sides of the fixture. A small piece of wire inserted in each side of the fixture is a convenient way to connect the DVM. Do not connect either end to ground. Set the meter to AC volts, autoranging. 2) Set the SR715/720 to its default conditions ([Recall] [0] [ENTER]).
PERFORMANCE TESTS Resistance Accuracy Table resistance 10.0 25.0 25.0 25.0 100.0 range 3 3 3 3 3 conditions 1 kHz series 1 kHz series 10 kHz series 100 kHz series 1 kHz series SR715 tol. + R tol. 9.9780 - 10.022 24.945 - 25.055 24.920 - 25.080 --------------99.780 - 100.22 SR720 tol. + R tol. 9.9930 - 10.007 24.983 - 25.018 24.970 - 25.030 24.945 - 25.055 99.930 - 100.07 100.0 400.0 400.0 400.0 1.6000k 2 2 2 2 2 1 kHz series 1 kHz series 10 kHz series 100 kHz series 1 kHz parallel 99.780 - 100.
PERFORMANCE TESTS Capacitance Accuracy Table capacitance 1.0n 1.0n 1.0n Frequency 1 kHz 10 kHz 100 kHz Range 0 1 2 SR715 tol. + C tol. .99780n - 1.0022n .99680n - 1.0032n ----------------- SR720 tol. + C tol. .99930n - 1.0007n .99880n - 1.0012n .99780n - 1.0022n 10.0n 10.0n 10.0n 10.0n 100 Hz 1 kHz 10 kHz 100 kHz 0 1 2 2 9.9780n - 10.022n 9.9780n - 10.022n 9.9680n - 10.032n ----------------- 9.9930n - 10.007n 9.9930n - 10.007n 9.9880n - 10.012n 9.9780n - 10.
PERFORMANCE TESTS SR715/720 PERFORMANCE TEST RECORD Serial # __________________ Date _________________ Tested by _________________________ Equipment used _____________________________________________________________________ ____________________________________________________________________________________ Functional Tests Front Panel Test Self Test Output Voltage Resistance Test 24.9 Ω 400 Ω 6.
PERFORMANCE TESTS Resistance Accuracy resistance 10.0 25.0 25.0 25.0 100.0 range 3 3 3 3 3 conditions 1 kHz series 1 kHz series 10 kHz series 100 kHz series* 1 kHz series Value ____________ ____________ ____________ ____________ ____________ Pass ____ ____ ____ ____ ____ Fail ____ ____ ____ ____ ____ 100.0 400.0 400.0 400.0 1.
CALIBRATION INTRODUCTION Calibration of the SR715/720 is composed of several parts: open and short circuit calibration, standard resistor calibration, and amplitude calibration. The open and short circuit calibrations are offset corrections to correct for any stray impedances of the test fixture. These calibrations may be performed at any time and should be done whenever the fixture is changed.
CALIBRATION Amplitude Calbytes Amplitude Calbyte Numbers 0 thru 94 Range 0 - 255 (1 byte) Amplitude Calbyte Organization Amplitude 0.10V 0.15V 0.20V 0.25V 0.30V 0.35V 0.40V 0.45V 0.50V 0.55V 0.60V 0.65V 0.70V 0.75V 0.80V 0.85V 0.90V 0.95V 1.
CALIBRATION Necessary Equipment Instrument Time Interval Counter Critical Specifications Time Interval Accuracy 1 ns max Recommended Model SRS SR620 DC/AC Voltmeter 5 1/2 digit DC accuracy True RMS AC to 100 kHz Fluke 8840A with Option -09 Standard Resistors Resistance known to 0.01% Q accuracy known to 25 ppm SRS calibration parts R0 95.300 kΩ R1 5.970 kΩ R2 374.0 Ω R3 25.10 Ω Fixture to BNC Adapter SRS SR728 Calibration Conditions Warm up time: At least 30 minutes Temperature: 23 °C ±2 °C 1.
CALIBRATION calbyte 0-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85-89 90-94 Amplitude Limits Table nominal voltage 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 1.000 limits 0.098 - 0.102 0.147 - 0.153 0.196 - 0.204 0.245 - 0.255 0.294 - 0.306 0.343 - 0.357 0.392 - 0.408 0.441 - 0.459 0.490 - 0.510 0.539 - 0.561 0.588 - 0.612 0.637 - 0.663 0.686 - 0.714 0.735 - 0.765 0.784 - 0.816 0.833 - 0.
CALIBRATION 3. Standard Resistor Calibration This procedure determines the value of the internal standards for the different frequencies and ranges. The SR715/720 does this by measuring a precisely known resistor and recomputing the values it uses when calculating the impedance of a part. These values are the primary accuracy standard of the instrument, so the exact value of the calibration resistor, both real and imaginary parts, must be known.
TROUBLESHOOTING Nothing Happens At Turn On Make sure that the power entry module on the rear panel is set for the ac line voltage for your region, that the correct fuse is installed, and that the line cord is inserted all the way into the power entry module. The selected line voltage may be seen through the clear window, just below the fuse. When the unit is plugged in and turned "ON", the unit's firmware version number and serial number will be briefly displayed. Then the self tests should execute.
TROUBLESHOOTING Error Messages The following lists explain all of the error messages that the SR715/720 can generate. The messages are divided into operational errors (errors in using the instrument), self-test errors, and calibration errors. The messages are listed alphabetically. Operational Errors These error messages may appear during normal front panel operation and generally are warnings for incorrect operation.
TROUBLESHOOTING Message Code Err XX Status Meaning 2 The SR715/720's ROM has a checksum error. XX is the checksum value. CPU Error 1 The SR715/720 has detected a problem in its CPU. Data Error 3 CPU RAM failed read/write test. Det Error 6 The square wave multiplier failed its DC rejection test. Drv Error i 7 The output drive circuitry failed its test. i is an error code indicating failure point.
TROUBLESHOOTING Calibration Errors These error messages can be generated by the open, short, and standard calibration procedures. If the SR715/720 fails calibration, try running the procedure again. Repeated failure can indicate a hardware problem. The parameter limits are fixed and are set so that all units should easily calibrate within those limits. The messages are listed alphabetically, also listed is the status value returned by the *CAL? command.
MAINETENANCE BUILT IN FIXTURE CLEANING Several times a year, both the radial and axial test fixtures should be examined for any build up of waxy coatings from lead material. If the contacts appear dirty they should be cleaned. To clean both fixtures, use a thick piece of paper or cardboard moistened with isopropyl alcohol or a mild cleaning solvent. Slide it back and forth between the contacts. Repeat until no further residue comes off. Allow the fixture to dry before making measurements.
MAINTENANCE After the fixture bracket is detached, remove the 1/4" nuts holding the fixture to the bracket. Slide the plastic lead catcher off the mounting studs and wires. The two halves of the fixture can now be removed. There are springs inside the fixture so take care to avoid losing any parts when sliding them out of the bracket. Slowly allow the fixture half to open and remove the springs, placing them somewhere safe. See the figure below for details on the assembly.
MAINETENANCE over the fixture and back of the unit. Finally, replace the four screws at the corners of the unit. SURFACE MOUNT TWEEZERS CLEANING To clean the SMD Tweezers, rub an eraser lightly across the inside surfaces of the tips. Blow any residue off the tip. REPLACEMENT The tips of the tweezers may need to be replaced from time to time. Use the Allen wrench supplied with the tweezers (1/16") to remove the screw holding the tip.
MAINTENANCE 6-8
SR715/720 PARTS LIST Main Board Parts List REF.
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SR715/720 PARTS LIST Miscellaneous and Chassis Assembly Parts List REF. U 802 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 SRS PART# 3-00449-342 0-00079-031 0-00187-021 0-00351-029 0-00400-026 0-00420-031 0-00500-000 1-00174-171 1-00175-171 1-00177-171 7-00425-720 VALUE 27C256-120 4-40X3/16 M/F 4-40X1/4PP 4-40X1/4TRUSSPH 4-40X7/8 PP 4-40X13/16 M/F 554808-1 18 COND DIL 28 COND DIL 30 CON DIL SR720-22 DESCRIPTION EPROM/PROM, I.C.
