Symmetricom 5071A Assembly And Service Manual
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Symmetricom 5071A Assembly And Service Manual

Primary frequency standard
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See also: Operation and Programming Manual
5071A Primary Frequency Standard
Assembly- Level Service
Manual
Rev. B, July 3, 2007
Part Number: 05071-90040

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Summary of Contents for Symmetricom 5071A

  • Page 1 5071A Primary Frequency Standard Assembly- Level Service Manual Rev. B, July 3, 2007 Part Number: 05071-90040...

  • Page 3: Assembly- Level Service Manual

    Although Symmetricom Global Services (SGS) is always available to help when you have questions, they cannot be expected to provide troubleshooting assistance when you are repairing the 5071A - That is the purpose of the 5071A Service Manual. 5071A Primary Frequency...
  • Page 4 This product is a safety Class I instrument (provided with a protective earth terminal). If this instrument is used in a manner not specified by Symmetricom, the protection provided by the equipment may be impaired.
  • Page 5 Indicates Alternating current. Indicates Direct current. Rack Mounting The Model 5071A Unit is designed for mounting in a standard 19-inch (48.26 cm) rack. Follow the rack manufacturer's instructions for mounting the Model 5071A Unit while observing the following guidelines: •...
  • Page 6 ENTIEREMENT COMPRISES ET SONT RENCONTREES. ----------------------------------------------------------------------------------------------------- WARNING: THE MODEL 5071A UNIT SHOULD ONLY BE PLUGGED INTO A GROUNDED RECEPTACLE. SYMMETRICOM RECOMMENDS THAT THE CHASSIS EXTERNAL GROUND BE CONNECTED TO A RELIABLE EARTH GROUND. ANY INTERRUPTION OF THE PROTECTIVE GROUNDING CONDUCTOR (INSIDE...
  • Page 7 Safety Considerations and Warranty Safety Considerations (contd) WARNING: FOR CONTINUED PROTECTION AGAINST FIRE, REPLACE THE LINE FUSE(S) ONLY WITH 250V FUSE(S) OF THE SAME CURRENT RATING AND TYPE (FOR EXAMPLE, NORMAL BLOW, TIME DELAY). DO NOT USE REPAIRED FUSES OR SHORT CIRCUITED FUSEHOLDERS.
  • Page 8 Symmetricom does not warrant that the operation of Symmetricom products will be uninterrupted or error free. If Symmetricom is unable, within a reasonable time, to repair or replace any product to a condition as warranted, the customer will be entitled to a refund of the purchase price upon prompt return of the product.
  • Page 9 Safety Considerations and Warranty Warranty (contd) Symmetricom will be liable for damage to tangible property per incident up to the greater of $300,000 or the actual amount paid for the product that is the subject of the claim, and for damages for bodily injury or death, to the extent that all such damages are determined by a court of competent jurisdiction to have been directly caused by a defective Symmetricom product.

  • Page 10: Declares Under Our Sole Legal Responsibility That The

    Directive) which is excluded from the RoHS Directive 2002/95/EC (reference Article 2, paragraph 1) requirements. Note: The Model 5071A is compliant when supplied with or without the High Performance Option. CE Marking first affixed 2007 We declare that the equipment specified above conforms to the above Directives and Standards.

  • Page 11: Table Of Contents

    Test 3 — Stability ......................21 Performance Test Record....................22 2. Service..........................25 Introduction ......................... 25 Returning the Instrument to Symmetricom for Service............26 To Provide Repair Information..................26 To Pack in the Original Packaging Materials ..............26 Pre-Troubleshooting Information ..................27 Safety Considerations .......................

  • Page 12: Contents

    1.0.5 CBT Warm Up......................40 1.0.6 Servo-Lock Warning State..................41 1.0.7 User-Input/Output Checks ..................41 1.0.8 5071A Profiling ....................... 42 1.0.9 Delayed Failures, Warnings, and Messages............. 44 Power-on Fatal-Error Diagnostic Tree (Subsection 1) ............. 45 Self Test Diagnostic Tree (Subsection 2) ................. 47 Warm-up And Fatal Error Diagnostic Tree (Subsection 3) ..........
  • Page 13 To Remove A17 CBT Assembly ..................168 Preparation ........................168 10890A or 10891A CBT Removal ................. 168 CBT Installation......................169 Operation Verification ....................171 Disposal Procedure for Symmetricom Cesium Beam Tubes .......... 172 To Remove A19 Reference Oscillator Module ..............173...
  • Page 14 5. Replaceable Parts ......................174 Introduction ........................174 Replaceable Parts Table..................... 174 How To Order A Part ......................174 Parts Identification ......................174 Contacting Symmetricom ....................175 6. Specifications........................179 Introduction ........................179 7. Service and Support ......................180 Index ............................. 182...

  • Page 15: Preface

    Instrument Identification Instrument identification is made from the serial number located on the rear panel of the 5071A. Symmetricom uses a two-part serial number with the first part (prefix) identifying a series of instruments and the second part (suffix) identifying a particular instrument within a non-repeating series. A Symmetricom assigned alpha character within the serial number identifies the country in which the instrument was manufactured.

  • Page 16: Instruments Covered By This Manual

    Instruments having a higher serial prefix are covered when required by one or more manual-change sheets included with this manual. If a required change sheet is missing, contact Symmetricom by phone or email using the information provided at the back of this manual.

  • Page 17: Performance Tests - Verifying Specifications

    Symmetricom is provided in Chapter 5. This chapter provides procedures to test the electrical performance of the 5071A Primary Frequency Standard, using the specifications listed in Chapter 6, “Specifications.” Three types of tests are provided: •...

  • Page 18: Test Record

    1. Performance Tests – Verifying Specifications Test Record Test Record The results of the Operational Verification, complete Performance Tests, and RS-232 Verification can be recorded on a copy of the Performance Test Record, located at the end of this chapter. Equipment Required Equipment required for the performance tests in this chapter is listed in the following table.
  • Page 19 1. Performance Tests – Verifying Specifications Equipment Required Table 1-1. Recommended Test Equipment (Continued) Digital Multimeter HP/Agilent 34401A Input Resistance: 10 MΩ Accuracy: 0.04% at 1 Vdc 40kV ac/dc High HP/Agilent 34300A Range: >= 5KV dc, input Z= 1 GΩ, Voltage Probe Accuracy: 2%, 10 MΩ...
  • Page 20 1. Performance Tests – Verifying Specifications Equipment Required Table 1-1. Recommended Test Equipment (Continued) BNC Cables, 50 Ω, 1 M long, quantity 4 BNC, and Data- HP/Agilent 10503A communication cables 24542U RS-232 Cable, 9-pin (jack) to 9-pin (jack) 50 Ω BNC In-line Feed through Adapters HP/Agilent 10100C 0960-0496...

  • Page 21: 5071A Operational Verification

    5071A Operational Verification 5071A Operational Verification Power-On Self-Tests and Servo Lock Inspect the 5071A for any damage (see the section titled “Initial Inspection” in Chapter 7 of the 5071A Operating and Programming Manual for detailed inspection information). Ensure that the ac-power setting, ac-line fuse (rear panel), and supplied power cord are appropriate for your ac-power source.
  • Page 22 1. Performance Tests – Verifying Specifications 5071A Operational Verification NOTE The 5071A powers up at shipment receipt with the following configuration: Output Ports: Port 1 5 MHz output Port 2 10 MHz output RS-232C: Baud rate 2400 Data bits Parity...

  • Page 23: Rear-Panel Output Signal Checks

    4 minutes to conserve energy if no front-panel key is pressed. Press any key to turn the backplane light back on. Connect one of the 5071A outputs to an input channel of the HP/Agilent 54600A with a 50-Ω feed through termination and BNC cable as shown in Figure 1-1.

  • Page 24: Serial Port Verification

    RS-232 Serial Port Verification Ensure that the correct hardware connections exist between the 5071A and your terminal, personal computer, or workstation for your remote operation needs as shown in Figure 1-2. Ensure that the 5071A and your data communications equipment (terminal) are powered-up and have passed their own self-tests.
  • Page 25 1. Performance Tests – Verifying Specifications 5071A Operational Verification Figure 1-2. RS-232C Cabling Setups...

  • Page 26: 5071A Complete Performance Tests

    5071A Complete Performance Tests 5071A Complete Performance Tests Before performing the following tests, the 5071A under test must have been in operation for at least 30 minutes. If you are initially starting the 5071A, follow the instructions in the “Power-On Self Tests” procedure under the Operational Verification Test on page 7.
  • Page 27 Connect the 5071A Port 1 to the HP/Agilent 3585B analyzer as shown in Figure 1-3. Set the 3585B for 50Ω input impedance. On the 5071A, set output ports 1 and 2 to 10 MHz using the front panel controls. See the section titled “Setting the Output Port Frequency” in the 5071A Operating and Programming Manual for instructions on how to do this.
  • Page 28 1. Performance Tests – Verifying Specifications 5071A Complete Performance Tests On the 5071A, set output ports 1 and 2 to 5 MHz using the front panel controls. Repeat step 3. Connect 5071A Port 2 to the HP/Agilent 3585B Spectrum Analyzer and repeat steps 2 through 5 to test Port 2.
  • Page 29 Connect the 5071A Port 1 to the 3585B analyzer as shown in Figure 1-4. Set the 3585B for 50Ω input impedance. On the 5071A, set output ports 1 and 2 to 10 MHz using the front panel controls. See the section titled “Setting the Output Port Frequency”...
  • Page 30 No spurious signals are on or above the −80 dBc display line between 9 MHz and 11 MHz for the 10 MHz output. On the 5071A, set output ports 1 and 2 to 5 MHz using the front panel controls.
  • Page 31 Connect the 5071A 1 MHz output to the 3585B Spectrum Analyzer as shown in Figure 1-5. Set the 3585B for 50Ω input impedance. On the 3585B, perform the following steps: a.
  • Page 32 Connect the 5071A 100 kHz output to the 3585B Spectrum Analyzer as shown in Figure 1-6. Set the 3585B for 50Ω input impedance. On the 3585B, perform the following steps: a.
  • Page 33 1. Performance Tests – Verifying Specifications 5071A Complete Performance Tests d. Press the “PEAK SEARCH” button, then the “MKR->REF LVL” button. e. Set the resolution bandwidth (RES BW) to 300 Hz and the video bandwidth (VIDEO BW) to 1 kHz.

  • Page 34: Test 2 - Frequency Accuracy

    5071A 10 MHz output and another primary frequency standard (5071A Primary Frequency Standard or better). An HP/Agilent K34-59991A Linear Phase Comparator is used to measure the phase between the 5071A under test and the reference standard. In this test, the reference standard must be of known accuracy. The...
  • Page 35 (Long-Life). Be sure the accuracy of the reference standard is known with sufficient precision to make this measurement accurately. Procedure The 5071A must be on for at least 30 minutes and the green continuous operation LED must be on. Connect the HP/Agilent K34-59991A Phase Comparator OUTPUT terminals to the strip chart recorder as shown in Figure 1-7.
  • Page 36 This shows that frequency difference between the unit under test and the reference is 4.9 parts in ten to the 13th. This is only an example. The − measured frequency accuracy of a 5071A should be 1 x 10 or better for a −...

  • Page 37: Test 3 - Stability

    Measurement System, a highly specialized test system. In order to perform properly, this system must contain a reference oscillator with phase noise characteristics that are equal to or better than the 5071A. Instructions for performing frequency domain stability tests can be found in the HP/Agilent 3048A system documentation.

  • Page 38: Performance Test Record

    1. Performance Tests – Verifying Specifications 5071A Complete Performance Tests Performance Test Record Model 5071A Primary Frequency Standard Serial Number: Repair/Work Order No. Test Performed By: Temperature: Date: Relative Humidity: Notes: Test Test Results Number Operational Verification Pass Fail Power-On Self-Tests/Servo Lock...
  • Page 39 1. Performance Tests – Verifying Specifications 5071A Complete Performance Tests Test Actual Number Description Reading Limits Long-Life: Frequency Accuracy ____________ ± 1x10 - High-Performance: ± 2x10 - Stability See Specifications table in Chapter 6 of Time Domain ____________ this manual.
  • Page 40 1. Performance Tests – Verifying Specifications 5071A Complete Performance Tests...

  • Page 41: Service

    Symmetricom or any other vendors. An updated list of available replacement parts from Symmetricom is provided in Chapter 5. This chapter provides service information for your 5071A and is divided into three major sections: •...

  • Page 42: Returning The Instrument To Symmetricom For Service

    RMA and return address information. If you do not have the original shipping container for the 5071A it is STRONGLY recommended that you first order the packaging kit part number 59991-91105 from Symmetricom before returning for repair.

  • Page 43: Pre-Troubleshooting Information

    2. Service Pre-Troubleshooting Information Place four more polystyrene corner blocks on top of the instrument to secure it. Do not return the manuals with the instrument. Return an accessory only when it is a part of the failure symptoms. Seal the shipping container securely. Apply the appropriate shipping labels.

  • Page 44: Recommended Test Equipment

    Pre-Troubleshooting Information Recommended Test Equipment Test equipment recommended for testing and troubleshooting the 5071A is listed in Chapter 1, “Performance Tests.” Substitute equipment may be used if it meets or exceeds the required characteristics listed in Table 1-1. Repair Considerations...

  • Page 45: Service Accessories

    Service Accessories Service accessories for troubleshooting the 5071A are available from Symmetricom. Table 2-1 lists the items in the 5071A Service Accessories Kit. The list includes the name, the part number, and a brief description and use of each item.
  • Page 46 2. Service Pre-Troubleshooting Information Table 2-1. Service Accessories Kit (05071-67003) Contents Accessory Part Number Service Manual 05071-90040 Corrective maintenance Extender board for short PCAs 05071-60051 A4, 6, 7, 8 diagnosis Extender board for long PCAs 05071-60052 A2,3 diagnosis 100 nA Current Source (powered by A6) 05071-60274 A14 diagnosis SO-8 SMT Dip clip (#5250 ITT Pomona)

  • Page 47: Assembly Identification And Location

    2. Service Pre-Troubleshooting Information Assembly Identification and Location The assembly number, name and part number of the 5071A assemblies are listed in Table 2-2. Figures 2-1 and 5-2, illustrate the replaceable assemblies and cables in the 5071A. Table 2-2. 5071A Assembly Identification...
  • Page 48 2. Service Pre-Troubleshooting Information Figure 2-1. Instrument Top View...

  • Page 49: Diagnostic Trees And Procedures

    Component-level troubleshooting is NOT supported in this manual, except for the A1 motherboard. Troubleshooting on the 5071A requires disassembly for access. Refer to the “Disassembly and Reassembly” procedures in chapter 4 for that information. Assembly specific tests and probing frequently requires the use of either a long or short PCA extender board.

  • Page 50: 5071A Diagnostic Tree Organization

    2. Service Diagnostic Trees and Procedures 5071A Diagnostic Tree Organization • Diagnostic-Tree Section 1 - Top-level Diagnostics Trees: provides the beginning entry point for the troubleshooting process; organized around start-up events, front-panel operation/messages, and rear-panel output/input signals. • Diagnostic-Tree Section 2 - Functional-Group Diagnostic Trees:...

  • Page 51: Top-Level Diagnostic Tree Organization

    1.0.3 Power On Fatal Error Check 1.0.4 Instrument Self Tests 1.0.5 CBT Warm Up 1.0.6 Servo-Lock Warning State 1.0.7 User-Input/Output Checks 1.0.8 5071A Profiling 1.0.8.1 Profiling Results Interpretation 1.0.8.2 Conclusion of Diagnostic Procedure 1.0.9 Delayed Failures, Warnings, and Messages 1.0.9.1 Delayed Fatal Errors 1.0.9.2 Delayed Warnings...
  • Page 52 Warning Message Diagnostic Tree (Diagnostic Subsection 4) 1.4.1 Warning Message Interpretation 1.4.2 Signal Gain at Range Limit/CBT Signal Low 1.4.3 5071A Profiling (CBT Performance Evaluation) 1.4.4 Power Source is Batt (Ignore this for Opt 048) 1.4.4.1 Ac Line Operation - Battery Indicator On 1.4.4.2 Instrument Ac Power Absent...

  • Page 53: Top-Level Diagnostic Tree (Diagnostic Section 1)

    When the complete procedure is performed on a functional 5071A, it will end at section 1.0.8.2 with no errors or failures. The operational verification and...

  • Page 54: Dc Input 1 And 2 Power Steering Circuit Check

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) If Yes: Go to, 1.0.2. If No: Disconnect power immediately and check the appropriate rear panel power fuse. If fuse is intact, Go to, 1.0.1.1. (For Opt. 048 Go to 1.0.1.1.0.) If fuse is blown, Go to, 2.1.1.1.0 (Power supply diagnostic tree). 1.0.1.1.0 DC Input 1 and 2 Power Steering Circuit Check Use the DC Input 1 and 2 Power Steering Schematic (Figure 2-1.)

  • Page 55: Dc-Supply Test/Log-Record Examination

    If the INFO/STATUS menu selections display Warming up, use the CONFIG, MODE, and STANDBY menu selections to place the 5071A into STANDBY mode. (This will put the instrument into a stable state if it has not gone to Fatal Error mode.) Record all information in the log (LOG/BROWSE menu selections).

  • Page 56: Power On Fatal Error Check

    INC again. e) Press DEC to halt Self test execution. QUESTION: Did the 5071A pass all the Self tests? If Yes: Go to, 1.0.5 If No: Go to, 1.2.1 (Self-test diagnostic tree). 1.0.5 CBT Warm Up Change operating mode to NORMAL (press CONFIG, MODE, and NORMAL), the instrument state changes to Warming up.

  • Page 57: Servo-Lock Warning State

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) 1.0.6 Servo-Lock Warning State QUESTION: Is the amber LED flashing? If Yes: Go to, 1.4.1, Warning-Message diagnostic tree. (For delayed error/warnings go to 1.0.9.) If No: Go to, 1.0.7. 1.0.7 User-Input/Output Checks Check the performance of the following outputs/inputs: (Refer to chapter 1, page 1-8 to verify operation and page 1-7 in the Operating and Programming manual for checking the Sync...

  • Page 58: 5071A Profiling

    1.0.8 5071A Profiling Successful completion of the preceding tests indicate that all functional blocks of the 5071A under test are operational. This is confirmed by the instruments' ability to lock-up its servo loops successfully with no errors. These tests are however, not sufficiently detailed to predict the accuracy or stability of the instrument, which could be degraded by noise or instability in the CBT and the electronic circuits.
  • Page 59 1. If a 5071A has been successfully tested as described above and fails to meet specifications, you may need to return the instrument to the nearest qualified repair facility. Contact Symmetricom for further assistance.

  • Page 60: Delayed Failures, Warnings, And Messages

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) 1.0.9 Delayed Failures, Warnings, and Messages The error messages covered in sections 1.1.1, 1.2.1, 1.3.1, and 1.4.1 describe the error conditions which can occur respectively at power-up, during self-test, during servo lock-up, and immediately following servo lock- up.

  • Page 61: Power-On Fatal-Error Diagnostic Tree (Subsection 1)

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) Power-on Fatal-Error Diagnostic Tree (Subsection 1) This subsection describes the power-on fatal-error diagnostic tree. It assumes that the internal +5, +12, and -12 dc-supply voltages are all present and within specifications. 1.1.1 Fatal-Error Interpretation Observe the log contents for any of the following error messages.
  • Page 62 3.1.1.1.0.) QUESTION: Is there +5 V at pin 1 and a toggling signal present on pins 2 and 3 of A2J2? If Yes: CBT ROM may be defective: contact Symmetricom for assistance. If No: Remove power, replace A2, and retest.

  • Page 63: Self Test Diagnostic Tree (Subsection 2)

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) Self Test Diagnostic Tree (Subsection 2) This subsection describes what to do after a Self-test fails. 1.2.1 Self-Test Failure Interpretation QUESTION: Which test(s) failed? (If 13/14: Repair A7 and retest.) If TEST 13, Interface register test, Remove power, replace A7, and retest.
  • Page 64 XOPTJ1 pin 44. QUESTION: Is the waveform correct? If Yes: Remove power, replace A3, and retest. (If the problem persists: remove power, replace A1, and retest; or contact Symmetricom for further assistance.) If No: Remove power, replace A8, and retest.

  • Page 65: Warm-Up And Fatal Error Diagnostic Tree (Subsection 3)

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) Warm-up And Fatal Error Diagnostic Tree (Subsection 3) This subsection describes the warmup- and fatal-error diagnostic tree. 1.3.1 Warm-Up/Operating Error Examine the log (LOG/BROWSE). QUESTION: Is the last item in the log an error code that appears similar to this: Error code: 000000a0 20000000 If Yes:...
  • Page 66 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) FIRST WORD (Rightmost word): 0 ⇐ Hex digit / \ / \ / \ / \ / \ / \ / \ / \ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ⇐ Binary digit | | | | | | | | | | | | | | | \_1.
  • Page 67 If FATAL ERROR #19 or #22, Go to, 1.3.3. A non-zero total in the first field of the right-most word indicates that the 5071A was being steered at the time of shutdown: it has no diagnostic significance. NOTE Additional diagnostic information may be obtained from any warnings or messages indicated by data in the error codes.
  • Page 68 CBT Ion-Pump current is high. When caused by poor vacuum (for example, due to prolonged storage) the condition may correct itself if the unit is placed into STANDBY mode for 24 hours. If the condition persists after this time, remove power and contact Symmetricom for assistance.
  • Page 69 CBT parameters could not be compensated sufficiently to allow continued operation. Repair is likely necessary, however a re-start of the 5071A should first be attempted as a possible remedy. If the failure re-occurs with the same message, contact Symmetricom to arrange repair/replacement of the CBT.
  • Page 70 Retest the instrument by cycling ac power. QUESTION: Does the instrument fail to lock-up, then display one of the same errors? If Yes: A CBT fault is indicated, contact Symmetricom for further assistance. If No: Continue the diagnostic procedures.
  • Page 71 Check the RF-level control current as described at 1.3.8. When all tests complete satisfactorily, cycle power to the instrument. QUESTION: Did warm-up fail with the same error message? If Yes: CBT is probably defective, contact Symmetricom for further assistance. If No: Continue the diagnostic procedure.
  • Page 72 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) 1.3.8 RF-Level Control-Current Test The amplitude of the microwave probe signal is controlled by an amplitude modulator in A15 driven with current generated from a DAC on A7. If control current is absent, amplitude modulation is lost. Remove power and disconnect the cable from A1J19 to A15J1.

  • Page 73: Warning Message Diagnostic Tree (Subsection 4)

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) Warning Message Diagnostic Tree (Subsection 4) This subsection describes the warning-message diagnostic tree. 1.4.1 Warning Message Interpretation Examine the log for any of the following entries (LOG/BROWSE menu selections) (Assembly/Module trees are located in diagnostic tree section 3.) QUESTION: What is the warning message? If WARNING is:...
  • Page 74 Top-Level Diagnostic Tree (Diagnostic Section 1) 1.4.3 5071A Profiling (CBT Performance Evaluation) The errors observed suggest deteriorating CBT performance. Use the 5071A Profiling software as described at 1.6.0 to evaluate CBT performance. QUESTION: Did the CBT pass the profiling performance evaluation.
  • Page 75 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) 1.4.4.2 Instrument AC Power Absent Reconnect the internal standby batteries and reapply ac power. (For Opt. 048 reapply ac power). Measure the dc voltage between TP5 on A11 and a common test point (not chassis ground), such as TP6,9, or 12 on A11.

  • Page 76: I/O Diagnostic Tree (Subsection 5)

    2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) I/O Diagnostic Tree (Subsection 5) This subsection describes the Input/Output (I/O) diagnostic tree. 1.5.1 Input/Output Faults Use the following list to find a fault-isolation procedure associated with the observed I/O problem. (Assembly/Module diagnostic trees are located in diagnostic tree section 3.) QUESTION: Which I/O was found at fault?

  • Page 77: Cbt Performance Evaluation (Subsection 6)

    Set up serial data communications link hardware between the 5071A and the computer. (Refer to chapter 4 of the 5071A Operating and Programming manual to connect the 5071A to the computer's COM1 or COM2 serial port.) Ensure that the 5071A's Baud rate is set to 2400 or greater.
  • Page 78 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) If the 5071A should return a prompt other than “scpi >“ or “E-xxx>“, it will not be possible to monitor and control the instrument with SCPI commands as documented in the manual.
  • Page 79 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) 1.6.1 5071A Profiling Results Evaluation A 5071A Profiling report example appears on the next page. You can use the example along with the explanations below to interpret your instrument’s profiling results. VCXO Control Value...
  • Page 80 2. Service Top-Level Diagnostic Tree (Diagnostic Section 1) =============================================== Output file from program CK5071A (rev. A.00.01) =============================================== DOS System time: 1994-01-25 16:25:07 5071A Status: ============= Instrument time: 1994-01-25 16:25:07 (49377) CBT Serial number: 3112A00102(H) Tube Type: 10891A Instrument Status summary:...

  • Page 81: Advisory Messages (Subsection 7)

    Check the analog signal chain (2.2.1.0), and the Electron Multiplier supply (3.7.2.1). If no problems are found with A6, A14, or A16 with the above procedures, the CBT may be faulty. Contact Symmetricom for further assistance.

  • Page 82: Functional-Group-Diagnostic Trees (Diagnostic Section 2)

    2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) Functional-Group-Diagnostic Trees (Diagnostic Section 2) This section provides functional-group-level diagnostic trees for the 5071A Primary Frequency Standard. Functional-group diagnostic trees necessarily evaluate two or more assemblies/modules when such operation is interactive. The cumulative operation of the constituent parts is analyzed as a whole.

  • Page 83: Power-Supply Diagnostic Tree (Functional Group Subsection 1)

    2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) Power-Supply Diagnostic Tree (Functional Group Subsection 1) This subsection describes the Power-supply diagnostic tree and provides information for fault isolation to: • A1 Motherboard, • T1 Toroidal power transformer, • A11 Steering-logic assembly, •...
  • Page 84 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.1.1.1.2 A11/A11 Cable Test Use a DMM to measure the voltage from A11TP5 to A11TPs 6, 9, or 12. Verify that the voltage is between 32 and 38 Vdc (45 and 51 Vdc for Opt. 048) with no more than 1 Vrms ripple.
  • Page 85 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.1.1.2.0 AC-Line Fuse Fault Isolation, Rule Out A11 Ensure that proper line fuse and line-switch setting (for the available ac-input voltage) are used. (See operating manual for details.) Replace ac-line fuse. Disconnect A11P101 to isolate the problem. Apply ac-line voltage again.
  • Page 86 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.1.2.3.0 A1 Fault Remove power, ensure interconnecting cables are not shorted, then either troubleshoot or replace A1, and retest. The problem is on the motherboard (A1), in one or more of the following: •...
  • Page 87 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.1.3.0.0 A12 Module Test Power on the instrument. Use a DMM to measure the A12 output voltages at the module solder-lug connections. Verify that they are within the ranges shown below: +5V supply: at least +5.28 Vdc +12V supply: at least +12.08 Vdc -12V supply: at least -12.08 Vdc QUESTION:...
  • Page 88 2.1.4.0.0 Ext. DC Input Fuse Fault The Ext. DC Input fuse blows when powering-on or running the 5071A. The assumption here is that ONLY the dc fuse blows, with the instrument operating normally from the ac line or internal standby battery for non-Opt.
  • Page 89 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.1.5.1.0 Internal-Battery Charger Test If the 5071A operates for less time than specified, the fault is either the battery or that it is not being charged properly. Verify charger operation as follows: Apply ac power and observe the instrument complete warm-up.

  • Page 90: Analog-Signal Chain Diagnostic Tree (Functional-Group Subsection 2)

    2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) Analog-Signal Chain Diagnostic Tree (Functional-Group Subsection 2) This subsection describes the analog-signal chain diagnostic tree. The tree provides information to check both A14 Signal-Amplifier module and A6 Servo assembly. 2.2.1.0 A6 TP 5 and 6 Voltage Test 1 Remove instrument power.
  • Page 91 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.2.2.0 A6J7 Voltage Test Use the DMM or oscilloscope to measure the voltage at A6J7 and record the result. QUESTION: Is the voltage between 0.00 and 0.05 volts? If Yes: Go to, 2.2.3.0. If No: Go to, 2.2.2.1.
  • Page 92 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.2.5.0 Analog-Signal Chain Transimpedance Test Connect the 100-nA current source input lead to A6, J4, pin 9 (closest to J5 and J6). (This applies a -100 nA input signal to A14.) Measure the voltage at A6J7. QUESTION: Is the voltage difference between +6.9 and +7.5? If Yes:...

  • Page 93: Rf-Chain Diagnostic Tree (Functional-Group Subsection 3)

    RF-Chain Diagnostic Tree (Functional-Group Subsection 3) This subsection describes the RF-chain diagnostic tree for the 5071A Primary Frequency Standard and provides fault isolation of, or pointers to diagnostic trees for, constituent RF-chain assemblies or modules. 2.3.1.0 RF-Chain Test Start Up Remove power by disconnecting external ac and dc power.
  • Page 94 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.3.3.0 A19 Output Amplitude and Frequency Test Program frequency counter to use internal timebase. (The frequency counter timebase must be calibrated to ensure an accuracy of 1×10 - or better.) Disconnect the semi-rigid cable from A9J5. Use the adapter cable to connect it to the input of the oscilloscope with a 50 Ω...
  • Page 95 Verify presence of a sine-wave with at least 6.0 Vp-p amplitude. Disconnect A9J1 from the oscilloscope. Reprogram frequency counter to use 10 MHz external reference from 5071A output. Use the frequency counter to verify presence of a 320 MHz ±0.1 Hz signal at A9J1.
  • Page 96 2. Service Functional-Group-Diagnostic Trees (Diagnostic Section 2) 2.3.8.1 131.771 kHz. Frequency Test Disconnect coax from A5J2. Connect a spectrum analyzer (HP/Agilent 8566) to the free end of the coax (not to A5J2). Adjust the spectrum analyzer to a center frequency of 131.7 kHz and a 10 kHz span.

  • Page 97: C-Field Diagnostic Tree (Functional-Group Subsection 4)

    Functional-Group-Diagnostic Trees (Diagnostic Section 2) C-Field Diagnostic Tree (Functional-Group Subsection 4) This subsection describes the C-field diagnostic tree for the 5071A Primary Frequency Standard. (Refer to the A2 connector pinout diagram ahead of procedure 3.1.1.1.0 for pin number and location.) 2.4.1.0 C-Field Current Test...

  • Page 98: Assembly/Module Diagnostic Trees (Diagnostic Section 3)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) Assembly/Module Diagnostic Trees (Diagnostic Section 3) This section provides diagnostic trees for individual assemblies and modules. Assembly and tree numbers in bold designate the trees that are actually present in this section. The following assemblies and modules are covered or are referenced to other sections/diagnostic trees: Motherboard (See section 2, Power-supply diagnostic tree.) CBT Controller assembly, tree 1: 3.1.1.1.0...

  • Page 99: A2 Cbt Controller Diagnostic Tree (A/M Subsection 1)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A2 CBT Controller Diagnostic Tree (A/M Subsection 1) This subsection describes the A2 Assembly diagnostic tree. The tree is divided into four functional subsections as follows: A2 Hot-Wire Ionizer tree A2 Thermistor tree A2 Mass-Spectrometer tree A2 Cesium-Oven tree Each of the functional subsections is designed to isolate a fault to one of the...

  • Page 100: A2 Hot-Wire Ionizer Diagnostic Tree

    A2 Hot-Wire Ionizer Diagnostic Tree This functional subsection describes the A2 hot-wire ionizer diagnostic tree for the 5071A Primary Frequency Standard. Performance of these tests is indicated by the presence of either a self-test or fatal error that reports a hot- wire ionizer fault.
  • Page 101 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.1.1.1.3 Hot-Wire Monitor Test (Current On) Place a 10 kΩ resistor between the pins listed below before each of the voltage measurements in steps 3 through 6. Use the SCPI command syst:print? to read the HW-Ionizer voltage. (Terminal-to-instrument via RS-232C data communication required.) Measure pins 1 and 37: reading should be between 20.0 and 21.0V Measure pins 1 and 38: reading should be between -20.0 and -21.0V...

  • Page 102: A2 Thermistor Diagnostic Tree

    A2 Thermistor Diagnostic Tree This functional subsection describes the A2 thermistor diagnostic tree for the 5071A Primary Frequency Standard. Performance of these tests is indicated by the presence of either a self-test or fatal error that reports a thermistor fault.
  • Page 103 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.1.2.1.3 Thermistor Monitor Test 1 (Current On) Place a 10 kΩ resistor between pins 1 and 7 on connector XA2P2 (48-pin connector on extender card). Use SCPI command syst:print?. (Terminal-to-instrument via RS-232C data communication required.) QUESTION: Is thermistor between 9.35 and 9.75 C°? If Yes:...

  • Page 104: A2-Mass-Spectrometer Diagnostic Tree

    Assembly/Module Diagnostic Trees (Diagnostic Section 3) A2-Mass-Spectrometer Diagnostic Tree This functional subsection describes the A2 mass-spectrometer diagnostic tree for the 5071A Primary Frequency Standard. Performance of these tests is indicated by the presence of either a self-test or fatal error that reports a mass-spectrometer fault.
  • Page 105 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.1.3.1.4 Mass-Spectrometer Monitor Test (− Current On) Place a 10 kΩ resistor between pins 3 and 37 on connector XA2P2. Use SCPI command syst:print? (Terminal-to-instrument via RS-232C data communication required.) QUESTION: Is Mass spec: between -9.5 and -11V? If Yes: Remove power, replace A2, and retest.

  • Page 106: A2 Cesium-Oven Diagnostic Tree

    A2 Cesium-Oven Diagnostic Tree This functional subsection describes the A2 cesium-oven diagnostic tree for the 5071A Primary Frequency Standard. Performance of these tests is indicated by the presence of either a self-test or fatal error that reports a cesium-oven fault.
  • Page 107 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.1.4.1.3 Cesium Oven Monitor Test (+ Current On) Place a 10 kΩ resistor between pins 1 and 36 connector XA2P2 (48-pin connector on extender card). Use SCPI command syst:print?. (Terminal-to-instrument via RS-232C data communication required.) QUESTION: Is CBT Oven Err: between 20.0 and 21.0C°? If Yes:...

  • Page 108: A5 Diagnostic Tree (A/M Subsection 2)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A5 Diagnostic Tree (A/M Subsection 2) This subsection describes the A5 87 MHz PLL module diagnostic tree. Ensure that the instrument is in Fatal Error mode. This enables A4 to NOTE provide a 131.77 kHz output. 3.2.1.0 Power-Supply Tests Check the +5V, +12V and both -12V terminals on A5 with a DMM.
  • Page 109 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.2.2.1 A9J3 80-MHz Signal Cable Test Disconnect cable from A9J3. Connect A9J3 to the 50 Ω input of an oscilloscope. (If a 50 Ω input is absent, use the high-impedance input with a 50 Ω coaxial-feedthrough terminator at the scope end of the coax).
  • Page 110 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.2.5.0 A5J101 87.36823-MHz Signal Test Connect the HP/Agilent 8566 spectrum analyzer (or equiv.) to A5J101. Set center frequency to 87.368 MHz and span to 10 kHz. Verify presence of an 87.368 MHz (±1 kHz) signal with a 0 ±3 dBm amplitude.

  • Page 111: A8 Diagnostic Tree (A/M Subsection 3)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A8 Diagnostic Tree (A/M Subsection 3) This subsection describes the A8 1 PPS Assembly diagnostic tree. 3.3.0. A8 Test Setup Remove instrument power. Mount A8 on the short extender board (05071-60051). Disconnect the CBT cable from A2J2 (this ensures power up to Fatal Error mode).
  • Page 112 If Yes: Retain the replaced assembly and retest. If No: A1 may be defective, contact Symmetricom for further assistance. 3.3.2. Clock Increment Test Set the Instrument LCD display to the CLOCK/Set Menu. Verify that the time (hh:mm:ss) display increments at one-second intervals.
  • Page 113 If Yes: Retain new A3 and retest. If No: A1 may be defective, contact Symmetricom for further assistance. 3.3.3. 1 PPS Outputs Test Reapply instrument power if required. Use the oscilloscope with 50 Ω input termination to check for 20 microsecond pulses at a rate of 1 pulse per second at each of the three external 1 PPS output connectors.
  • Page 114 Reconnect the verified cables and BNC connectors. QUESTION: Are any of the five SMB-to-BNC cable assemblies open or shorted? If Yes: Replace the cable assembly as required, reinstall A8 and retest. If No: A1 may be defective, contact Symmetricom for further assistance.

  • Page 115: A9 Diagnostic Tree (A/M Subsection 4)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A9 Diagnostic Tree (A/M Subsection 4) This subsection describes the A9 Frequency Multiplier module diagnostic tree. 3.4.1.0 A9 Module Power Checks Check the -12V and +5V terminals on A9 with a DMM and verify that: -12V is between -12 and -12.5V to chassis Verify +5V is between 5.25 and 5.5V to chassis.
  • Page 116 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.4.2.1 A19 10-MHz Output Test Disconnect cable from A19 output connector. Connect A19 output connector to a scope with 50 Ω input impedance (If the scope doesn't have a 50 Ω input, use the high impedance input with a 50 Ω coaxial feedthrough terminator installed at the scope end of the coax).

  • Page 117: A10 Diagnostic Tree (A/M Subsection 5)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A10 Diagnostic Tree (A/M Subsection 5) This subsection describes the A10 Output Frequency Distribution Amplifier Module diagnostic tree. 3.5.1.0 A10 Module Power Checks Check the +12V and +5V terminals on A10 with a DMM and verify +12V is between +12 and +12.5V to chassis.
  • Page 118 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.5.2.1 A9J2-to-A10J5 Cable Test Disconnect cable from A9J2. Connect A9J2 to a scope with 50 Ω input impedance (If a 50 Ω input is absent, use the high impedance input with a 50 Ω coaxial feedthrough terminator at the scope end of the coax).
  • Page 119 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.5.3.1.1 A10 Port-1 Frequency-Selection Error Test Jumper the SEL-A terminal on A10 to chassis ground. Recheck port 1 with scope. Verify presence of 5-MHz signal. Remove clip lead. QUESTION: Is a 5-MHz signal present? If Yes: Remove power, replace A7, and retest.
  • Page 120 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.5.4.0 A10 Port-2 Test Connect port 2 on the rear panel to the 50 Ω input of a scope using coax. (If a 50 Ω input is absent, use the high impedance input with a 50 Ω coaxial feedthrough terminator at the scope end of the coax).
  • Page 121 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.5.4.2.1 A10 Port-2 Frequency Selection Error Test Check SEL A on A10 with a DMM. Verify that it is no greater than 2 volts. QUESTION: Is the SEL A voltage 2 or less? If Yes: Go to, 3.5.4.2.2.
  • Page 122 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.5.6.0 A10 100-kHz Output Test Connect the 100-kHz output connector on the rear panel to the 50 Ω input of a scope using coax. (If a 50 Ω input is absent, use the high impedance input with a 50 Ω...

  • Page 123: A15 Diagnostic Tree (A/M Subsection 6)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A15 Diagnostic Tree (A/M Subsection 6) This subsection describes the A15 9.2 GHz Microwave Generator Module diagnostic tree. 3.6.1.0 A15 Module Power Check Check the +4.5V terminal on A15 with a DMM. Verify +4.5V is between +4.4 and +4.6V to chassis.
  • Page 124 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.6.2.0 320-MHz Signal Test Adjust spectrum analyzer input attenuation for a +30 dBm. maximum signal. Disconnect cable from A15J4. Connect the free end of the cable to the spectrum analyzer. Verify the presence of a 320-MHz signal with at least +18 dBm amplitude. Reconnect cable to A15J4.
  • Page 125 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.6.4.0 A15J5 Signal Test Disconnect semi-rigid coax cable from CBT. Disconnect cable from A15J1. Connect semi-rigid coax cable to an HP/Agilent 8566B microwave spectrum analyzer using appropriate microwave coaxial test cable (GoreTex 32R01R01048.0). Verify the presence of a signal with no sidebands between 9180 and 9205 MHz, having an amplitude between -10 and -30 dBm.
  • Page 126 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.6.5.0 A15J1 Power-Level Check Connect A15J1 to a +2.5 Vdc power supply. Check spectrum analyzer again and verify that amplitude has increased to at least 0 dBm. Disconnect power supply from A15J1 and reconnect internal cable to A15J1. QUESTION: Did the amplitude on the spectrum analyzer increase to at least 0 dBm?

  • Page 127: A16 Diagnostic Tree (A/M Section 7)

    3.7.1.0 A16 Preliminary Set-Up Remove instrument power Mount the A2 CBT Controller on the long extender Disconnect A19 from A1 at A1J11, this will prevent the 5071A from leaving the warming up mode for 45 minutes after turn-on. Disconnect semi-rigid cable at A9J5.
  • Page 128 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) QUESTION: Is the measured voltage when multiplied by the high voltage probe calibration factor between 3.3 kV and 4.3 If Yes: Go to, 3.7.1.2 If No: Remove power, replace A16 and retest. 3.7.1.2 Ion Pump Return Current Test Use the INFO/PUMP menu selection to display the output of the Ion Pump current monitor circuit.
  • Page 129 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.7.1.3.1 Ion Pump Current Monitor Diagnosis Power down the instrument, and wait one minute for the A16 module voltages to bleed down. Disconnect the A16 module from A1 at A1J12. Re-power the instrument, wait 15 seconds, and use the INFO/PUMP menu selection to display the Output of the Ion Pump current monitor circuit on the LCD display.
  • Page 130 Ground the high voltage probe return to the 5071A chassis, and plug the probe output into the DMM. Set voltage mode and at least 10.0 Volts range. The input impedance of the DMM must equal that specified for the high- voltage probe.
  • Page 131 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.7.2.2 Electron Multiplier Supply Control Current Test Remove instrument power, and wait one minute for the A16 module voltages to bleed down. Power up and check that the instrument enters the warming up mode in about 10 seconds.

  • Page 132: A18 Diagnostic Tree (A/M Subsection 8)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A18 Diagnostic Tree (A/M Subsection 8) This subsection describes the A18 9.2 GHz PLL Module diagnostic tree. 3.8.1.0 A18 Module Power Check Check the +12V, -12V, and +5V terminals on A18 with a DMM. Verify +12V is between +12 and +12.5V to chassis.
  • Page 133 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.8.2.1 A5 87.368230-MHz Input Cable Test Disconnect cable from A5 output connector. Connect A5 output connector to a scope 50 Ω input (If a 50 Ω input is absent, use the high-impedance input with a 50 Ω coaxial-feedthrough terminator at the scope end of the coax).
  • Page 134 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.8.3.2 A15 +4.5V Test Measure the dc voltage on the +4.5V terminal on A15 (accessible on the underside of the instrument when the bottom cover is removed). Verify voltage between +4.4V and +4.6V. QUESTION: Is voltage correct? If Yes:...
  • Page 135 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.8.4.0 A18J4 Signal Input Test Disconnect cable from A18J4 and reconnect that cable to the input of a 2- way 3-dB. power splitter. Connect one of the power-splitter outputs to A18J4 and the other to a spectrum analyzer.

  • Page 136: A19 Diagnostic Tree (A/M Subsection 9)

    2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) A19 Diagnostic Tree (A/M Subsection 9) This subsection describes the diagnostic tree for the A19 module and associated circuits on A6. The A19 module is an ovenized voltage-controlled, quartz-crystal oscillator (VCXO), it receives oven and oscillator power from the A6 module.
  • Page 137 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.9.1.2 A19 Loaded Power-Supply Voltages Remove power and reconnect A19 by firmly seating the plug at A1J11. Reapply power. (Wait until LCD displays Fatal Error.) Measure A19 supply voltages with a DMM at test points TP9, TP8 and TP7 on A6 to verify compliance as follows: TP9, (+12 v nominal), more than 11.75 and less than 12.75 volts.
  • Page 138 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.9.1.3 A6J4.1 and A6J4.9. Reference Voltage Test Verify reference voltages on A6J4.1/A6J4.9. with a DMM: A6J4.1 (nominal 5.000) > 4.995 and < 5.005 volts A6J4.9 (nominal -5.000) > -5.005 and < -4.995 volts QUESTION: Are the voltages correct? If Yes:...
  • Page 139 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.9.1.4.1. EFC Voltage Test (2) Unplug the A19 oscillator from A1-J11 and repeat the measurement procedure described in 3.9.1.3. QUESTION: Do the measured and calculated EFC voltages agree to within 0.03 volts? If Yes: Remove power, replace A19, and retest.
  • Page 140 2. Service Assembly/Module Diagnostic Trees (Diagnostic Section 3) 3.9.1.7 A19 Signal-Frequency Test Connect the output of the semi-rigid cable to the frequency counter with a 50 Ω input terminator. Observe the A19 frequency with an accuracy of ±1Hz. (The counter timebase must be calibrated to an accuracy of better than 1×10 Calculate the nominal output frequency of the A19 from the EFC control percentage using the equation:...

  • Page 141: Theory Of Operation

    All references to internal-battery power, battery status or battery operation, do not apply for 5071A Option 048. Option 048 does not have an internal Note standby battery.

  • Page 142: Simplified Functional Description

    3. Theory of Operation Introduction Simplified Functional Description This section provides a simplified overview of the instrument's operation along with the function of each block (listed below) as shown in Figure 3-1. 1. Front panel and remote instrument control, 2. 10 MHz reference-source/microwave probe signal synthesis, 3.

  • Page 143: Simplified Functional Description

    3. Theory of Operation Simplified Functional Description Simplified Functional Description This section provides the simplified functional description of the 5071A Primary Frequency Standard. The 5071A provides extremely accurate and stable sine-wave outputs that are within five to ten parts in 10 of the internationally accepted definition of frequency.

  • Page 144: Instrument Control Block

    3. Theory of Operation Simplified Functional Description Instrument Control Block This block provides front panel and remote instrument management with a keypad-LCD/menu interface or via SCPI (Standard Commands for Programmable Instruments) commands transferred through the RS-232C serial port. The block consists of microprocessor, front panel, and interface assemblies, and the I-bus that, together facilitate control of all internal housekeeping, servo loop, diagnostic, and system status instrument functions.

  • Page 145: Analog Signal Chain Block

    3. Theory of Operation Simplified Functional Description Analog Signal Chain Block The CBT output signal is amplified by the analog signal chain and converted into digital samples that are fed to the microprocessor (via VFC/VFC clock lines) in the instrument control block. The microprocessor uses the samples to calculate corrections to the microwave probe signal frequency and amplitude.

  • Page 146: Functional Block Descriptions

    Figure 3-2 is an overall block diagram of the 5071A that shows all assemblies and modules within the six functional blocks. The blocks and their assembly/module components and connections are discussed and tabulated in approximate order of signal flow within each block.
  • Page 147 3. Theory of Operation Functional Block Descriptions Figure 3-2. 5071A Overall Block Diagram...
  • Page 148 3. Theory of Operation Functional Block Descriptions Figure 3-2. 5071A Overall Block Diagram (Continued)

  • Page 149: Instrument Control Block

    3. Theory of Operation Functional Block Descriptions Instrument Control Block The instrument control block consists of the A3 microprocessor, A7 Interface, A13 front panel assemblies, I-bus, and operating firmware. It has five inputs: a. front panel keypad entry, b. RS-232C, c.
  • Page 150 3. Theory of Operation Functional Block Descriptions The rear-panel Status Output provides a way to monitor instrument operation. In default mode it tells when the front-panel continuous-operation LED turns off. This output is SCPI command programmable via RS-232C port to go active with other combinations of internal instrument events.
  • Page 151 Operation, Warning, Standby, and Fatal Error. This subsection describes the instrument's behavior in each of these modes. Power On Mode: When power is applied, the 5071A starts operation in the Power On mode. The firmware checks the functions of the A3 board and determines if all other assemblies and modules are present (Power-on Self- tests).
  • Page 152 Warm Up or Normal Operation modes. This mode can be used to run diagnostic self tests or to store the 5071A while maintaining the CBT for ready use. The ion pump remains on, preserving the CBT vacuum.

  • Page 153: Reference Oscillator/Rf Chain Block

    3. Theory of Operation Functional Block Descriptions Reference Oscillator/RF chain Block The Reference Oscillator/RF chain Block consists of the A19 reference oscillator module, A9 frequency multiplier, A5 87 MHz PLL module, A4 digital synthesizer, A18 9.2 GHz PLL module, and A15 9.2 GHz Microwave Generator module.
  • Page 154 3. Theory of Operation Functional Block Descriptions Table 3-2. Reference Oscillator/RF Chain Block Interconnections Source Destination Module or From Path To Path Module or Assembly Connectors Signal Name Connectors Assembly A6J5 EFC Control A19J108xx A19J1 10 MHz Reference A9J5 A9J4 80 MHz A8J3 A9J2...

  • Page 155: Cesium Beam Tube Block

    3. Theory of Operation Functional Block Descriptions Cesium Beam Tube Block The Cesium Beam Tube block consists of the A2 CBT Controller, A16 High Voltage Supply module, and A17 CBT. It has three inputs and one output. A2 receives command input from the I-bus to generate five functional signals: a.
  • Page 156 3. Theory of Operation Functional Block Descriptions Table 3-3. Cesium Beam Tube Block Interconnections Source From Path To Path Destination Module or Connectors Connectors Module or Assembly Pin # in italics Signal Name Pin # in italics Assembly XA2J1 Control/Monitor (3) A1J12 28/29/30 Long White...

  • Page 157: Analog Signal Chain Block

    3. Theory of Operation Functional Block Descriptions Analog Signal Chain Block The analog signal chain block consists of the A14 signal-amplifier module and A6 servo assembly. This block has three inputs and three outputs providing a means of converting the CBT error-signal output into the EFC voltage signal required by the A19 module EFC input.
  • Page 158 3. Theory of Operation Functional Block Descriptions Table 3-4. Analog Signal Chain Block Interconnections Source From Path To Path Destination Module or Connectors Connectors Module or Assembly Pin # in italics Signal Name Pin # in italics Assembly A17P1 CBT Output A14J1 A14J2 A14 Vout...

  • Page 159: Input/Output Block

    3. Theory of Operation Functional Block Descriptions Input/Output Block The input/output block consists of the A8 1PPS assembly and A10 Output Frequency Distribution Amplifier module. This block has five inputs and nine outputs. A10 receives an 80-MHz sine-wave signal from A9, SEL-A, and SEL-B select inputs from A7 via the I-bus which are used to create the 5/10-MHz programmable outputs for ports 1 and 2 along with fixed 1-MHz, and 100-kHz outputs routed to the appropriate rear panel connectors.

  • Page 160: Power Supply Block

    Functional Block Descriptions Power Supply Block All references to internal-battery power, battery status or battery operation, do not apply for 5071A Option 048. Option 048 does not Note have an internal standby battery. The Power Supply Block consists of LF1 line filter/cable assembly, T1...
  • Page 161 3. Theory of Operation Functional Block Descriptions Table 3-6 . Power Supply Block Interconnections Source Destination Module or From Path To Path Module or Assembly Connectors Signal Name Connectors Assembly LF1 Cable 100-240 Volts AC Power, T1 Cable-In T1 Xfmr (voltage selected on LF1) T1 Xfmr T1 Cable-Out...

  • Page 162: A1 Motherboard Circuit Description

    3. Theory of Operation Functional Block Descriptions A1 Motherboard Circuit Description A1 routes signals and power within the instrument via interconnect lines and buses. A1 has seven slots for plug-in boards (each plug-in board has two connections to A1), and a power supply section. A1 also has jacks for power/control/monitor functions for all the modules in the instrument.

  • Page 163: A11 Power Steering Logic Assembly

    3. Theory of Operation Functional Block Descriptions This current opens the ac-line fuse before the energy flowing through the above mentioned components can damage them. Resistor A1R6 pulls the gate of the SCR (A1CR1) to ground so it cannot float - causing a false crowbar trip.
  • Page 164 3. Theory of Operation Functional Block Descriptions Figure 3-3. A1 Power Supply/Distribution Schematic Diagram...
  • Page 165 3. Theory of Operation Functional Block Descriptions Figure 3-3. A1 Power Supply/Distribution Schematic Diagram (Continued)
  • Page 166 3. Theory of Operation Functional Block Descriptions Figure 3-4. A1 Slot/Module Interconnect Diagram...
  • Page 167 3. Theory of Operation Functional Block Descriptions Figure 3-4. A1 Slot/Module Interconnect Diagram (continued). This schematic also applies for Opt. 048...
  • Page 168 3. Theory of Operation Functional Block Descriptions Figure 3-5. Power Supply Block Diagram...
  • Page 169 3. Theory of Operation Functional Block Descriptions Option 048 Schematic Block Diagrams The following figures 3-6 to 3-8 are the corresponding schematics for an option 048 instrument. Figure 3-6. Opt. 048, A1 Power Supply/Distribution Schematic Diagram...
  • Page 170 3. Theory of Operation Functional Block Descriptions Figure 3-6. Opt. 048, A1 Power Supply/Distribution Schematic Diagram (Continued)
  • Page 171 3. Theory of Operation Functional Block Descriptions Figure 3-7. Opt. 048, A1 Slot/Module Interconnect Diagram...

  • Page 172: Figure 3-8. Opt. 048, Power Supply Block Diagram

    3. Theory of Operation Functional Block Descriptions Figure 3-8. Opt. 048, Power Supply Block Diagram...

  • Page 174: A12 Dc-Dc Power Converter Module

    3. Theory of Operation Functional Block Descriptions A12 Dc-Dc Power Converter Module The primary components on A12 module are three resonant zero-current switching Dc-Dc converter modules (A12U1-U3). There is a converter module for each power supply voltage (+5V, +12V, and -12V). Both the input and output ports of each module are heavily filtered.
  • Page 175 3. Theory of Operation Functional Block Descriptions Figure 3-9. A1 Component Locator Diagram...

  • Page 176: Replacing Assemblies - Disassembly And Reassembly

    Disassembly and Reassembly Introduction This chapter contains the instructions for removing major assemblies in the 5071A. To install an assembly, reverse the removal instructions (except for A17 CBT). HAZARDOUS VOLTAGES ARE ON THE A16 POWER SUPPLY MODULE. WAIT AT LEAST THREE MINUTES FOR THE...

  • Page 177: Do This First

    Do This First Do This First Before performing any of the removal and replacement procedures, turn off the 5071A by removing the ac-line power cord from the rear-panel ac line socket, disconnecting both internal- standby batteries, and external-dc power input if present.

  • Page 178: To Remove The A2 Cbt Control Assembly

    Due to the cost and complexity of the process, the A1 Motherboard Assembly is no longer available for repair and replacement by the user. Contact Symmetricom Customer Assistance for repairs and service. No parts are available for the A1 Motherboard.

  • Page 179: To Remove A10 Output Frequency Distribution Amplifier Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A10 Output Frequency Distribution Amplifier Module To Remove A10 Output Frequency Distribution Amplifier Module Ensure that the top, bottom, right-side, and inner-RF shield covers are removed. Disconnect all SMA, SMB, and module-to-A1 cable assembly connections for A9, A10, and A18.

  • Page 180: To Remove A12 Dc-Dc Power Converter Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A12 Dc-Dc Power Converter Module To Remove A12 Dc-Dc Power Converter Module Ensure that the top, bottom, and left-side covers are removed. Remove 3 screws from the plate that holds A16 in place, attached at the top of A12 (1 screw) and the Toroid power transformer T1 (2 screws).

  • Page 181: To Remove A13 Front Panel Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A13 Front Panel Module To Remove A13 Front Panel Module Use the following procedure to remove the entire A13 front-panel assembly and the PCB contained. No other lower-level parts are available for replacement on this assembly.

  • Page 182: To Remove A14 Signal Amplifier Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A14 Signal Amplifier Module To Remove A14 Signal Amplifier Module Ensure that the top cover and inner-RF (top) shield are removed. Clip the wire tie that bundles the A19 input/output SMA connector cable assemblies.

  • Page 183: To Remove A15 9.2 Ghz Microwave Generator Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A15 9.2 GHz Microwave Generator Module To Remove A15 9.2 GHz Microwave Generator Module Follow the instructions as described in “To Remove the Covers”. Place the instrument on its side. On the bottom side of the instrument, loosen all SMA connectors from A15 J1 through J5.

  • Page 184: To Remove A17 Cbt Assembly

    VCXO set-point. Refer to procedure 3.9.1.8 in chapter 2. Preparation If any questions about operation and programming arise while performing the procedures in this section, refer to the 5071A Operating and Programming Manual (part number 05071-90041). With power still applied to the instrument do the following:...

  • Page 185: Cbt Installation

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A17 CBT Assembly Look for the black coax cable that comes from the left side of the CBT and enters under a perforated RF cover. This is held in place with a tie wrap in a bundle with other wires.
  • Page 186 4. Replacing Assemblies - Disassembly and Reassembly To Remove A17 CBT Assembly 14 Affix snugly, but DO NOT TIGHTEN the brackets to hold the CBT in place, allowing for rotation of the CBT. 15 Rotate the CBT so that the SMA nut and rigid coax are aligned as straight as possible with the connector on the Microwave Adapter.

  • Page 187: Operation Verification

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A17 CBT Assembly Operation Verification Be sure the printer/terminal is on and that there will be a hard copy of the information captured. Connect power to the instrument, noting the time. If the message “Cs Oven is Up”...

  • Page 188: Disposal Procedure For Symmetricom Cesium Beam Tubes

    Beam Tubes Both the Long-Life (10890A) and High Performance (10891A) Cesium Beam Tubes contain non-radioactive cesium. After a defective cesium beam tube has been removed from the 5071A chassis, it must be disposed of properly, applying to all 5071A customers.

  • Page 189: To Remove A19 Reference Oscillator Module

    4. Replacing Assemblies - Disassembly and Reassembly To Remove A19 Reference Oscillator Module To Remove A19 Reference Oscillator Module Refer to the A14 removal and replacement procedure near the middle of this section. Use the appropriate steps to remove and replace A19. Reverse the order of steps used to install a new/functional module...

  • Page 190: Replaceable Parts

    Parts List are the Part Number and the quantity of the part you want. If the part you want is NOT identified in the manual, then it is not available for replacement and the 5071A must be sent to Symmetricom for servicing. Table 5-1 lists those parts that can currently be purchased.

  • Page 191: Contacting Symmetricom

    5. Replaceable Parts How To Order A Part Contacting Symmetricom When ordering parts, contact your Symmetricom sales representative or distributor. They can assist in placing your order. To arrange for service and repair, contact Symmetricom Customer Assistance.
  • Page 192 5. Replaceable Parts How To Order A Part Table 5-1. 5071A Replaceable Parts Reference Part Number Description Designation Not Available Motherboard 05071-60202 CBT Controller 05071-60003 Microprocessor 05071-60004 Digital Synthesizer 05071-60272 87 MHz PLL Module 05071-60006 Servo 05071-60007 Interface 05071-60008 1 PPS...
  • Page 193 5. Replaceable Parts How To Order A Part Table 5-1. 5071A Replaceable Parts (Continued Reference Part Number Description Designation MP27 5062-3977 Rack Kit - No Front Handle 0510-0182 Door Latch 1251-0126 External DC Mating Connector, 5-pin Circular 1400-3290 Rack Slide Hardware Kit Rack Slide (One pair).
  • Page 194 5. Replaceable Parts How To Order A Part...

  • Page 195: Specifications

    Specifications 6. Specifications Introduction The information in this chapter is identical to that found in the 5071A Operating and Programming manual P/N 05071-90041. Please refer to Chapter 6 in that document for any references to specifications in this manual.

  • Page 196: Service And Support

    Service and Support 7. Service and Support Symmetricom's Customer Assistance Centers are a centralized resource to handle all of your customer needs. Customer Assistance Center Telephone Numbers: • Worldwide (Main Number): 1-408-428-7907 • USA, Canada, Latin America including Caribbean, Pacific Rim including asia, Australia and New Zealand: 1-408-428-7907 •...

  • Page 198: Index

    Harmonic distortion check for 5 and 10 MHz outputs 10 Cable interconnections analog-signal chain block Harmonic distortion test setup cesium beam tube block HP 5071A diagnostic tree organization input/output block Input/output block 129, 143 instrument control block Input/output block interconnections...
  • Page 199 Index Instrument control block 128, 133 A19 reference oscillator module Instrument control block interconnections covers, top, bottom, and side Repair strategy, HP 5071A xiii Instrument top view Insulation resistance test Repair tools Internal-standby batteries Replacing assemblies Returning the instrument to HP...
  • Page 200 Index overall block diagram A16/CBT excess ion-pump current test overvoltage protection circuit A18 mon voltage test A18 average mon voltage test power supply block reference oscillator rf-chain block A18 mon signal ac-content test simplified functional description 126, 127 A18 power check A18, A15 +4.5V test analog-signal chain block cesium beam tube block...
  • Page 201 A9 10 MHz signal test ground continuity test A9 80 MHz signal test HP 5071A profiling (CBT performance evaluation) A9 J1 320 MHz signal test A9 module power checks HP 5071A profiling results evaluation A9, A19 10 MHz output test...
  • Page 202 Index sequencer error test VCXO control value 43, 63 service accessories visual inspection servo-lock warning state warm up and fatal error diagnostic tree signal gain at range limit/CBT signal low warm up error interpretation signal to noise ratio warning message diagnostic tree tools, special warning message interpretation top-level diagnostic tree...

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