HP 181A 150

Chapter 3 Replacing Assemblies

Introduction

3

WARNING

CAUTION

Introduction

This chapter contains the instructions for removing major assemblies in the HP 53131A/132A/181A. To install an assembly, reverse the removal instructions.

This chapter provides the following disassembly and reassembly procedures:

HAZARDOUS VOLTAGES ARE ON THE POWER SUPPLY ASSEMBLY. UNPLUG THE INSTRUMENT, THEN WAIT AT LEAST SIX MINUTES FOR THE CAPACITORS ON THE POWER SUPPLY ASSEMBLY TO DISCHARGE BEFORE WORKING ON THIS INSTRUMENT.

Do not replace assemblies with the instrument turned on. Damage to components can occur.

Refer to Chapter 5, “Replaceable Parts,” for the part number of the assemblies.

3-2	Assembly-Level Service Guide

Contents

Assembly-Level Service Guide Page Assembly-LevelService Guide Page Contents Preface How to Use This Guide Description of the 225 MHz Counters Options HP 53131A/132A Complete Performance Tests Test 1: Time Interval (HP 53131A/132A Only) Test 2: Trigger Level (HP 53131A/132A Only) Test 3: Channels 1 and 2 Frequency Sensitivity (HP 53131A/132A Only) Test 5: Option 030/050/124 Channel 3 Frequency Sensitivity (HP 53131A/132A Only) Test 6: Option 030/050/124 Channel 3 Frequency Accuracy (HP 53131A/132A Only) Test 7: Peak Volts, Channels 1 and 2 (HP 53131A/132A HP 53181A Complete Performance Tests Test 1: Trigger Level (HP 53181A Only) Test 2: Channel 1 Frequency Sensitivity (HP 53181A Test 3: Channel 1 Frequency Accuracy (HP 53181A Test 4: Option 015/030/050/124 Channel 2 Frequency Service Returning the Instrument to Hewlett-Packardfor Service About the HP 53131A/132A Calibration Menu The HP 53131A/132A Calibration Procedures About the HP 53181A Calibration Menu The HP 53181A Calibration Procedures Pre-TroubleshootingInformation Troubleshooting the Counter 3 Replacing Assemblies Tools Required Do This First To Remove the Cover To Remove the Front Bezel Retrofitting Options To Retrofit A3 1.5/3.0/5.0/12.4 GHz Channel Assembly (Option 015/030/050/124) To Retrofit A5 DC Power Input Assembly (Option To Retrofit A6 High Stability Timebase Assembly To Retrofit the Rear Terminals (Option 060) Backdating Manual Changes Older Instruments Backdating Hardware Backdating Firmware Page Preface Instruments Covered by this Guide Assembly-LevelService Guide Organization How to Order Guides HP 53131A HP 53132A HP 53181A Page NOTE Hardware Support Accessories Supplied Accessories Available Page Page Introduction Operational Verification Complete Performance Tests Optional HP-IBVerification For HP 53131A/132A Counters For HP 53181A Equipment Required Table 1-1.Recommended Test Equipment HP 53131A/132A/181A Operational Verification Power-OnSelf Tests 1 Inspect the Counter for any damage 2 Make sure no cables are connected to the input channels (rear and front panels) of the Counter 5Verify that the following happens: •SELFTST: PASS is displayed HP-IB AT n Freq Page Run Self Test 1Disconnect the input signals from the Counter Power down (turn off the Counter), press and hold Recall (Utility) 3Press Recall key until TEST: ALL ? is displayed Page External Arm Test (HP 53131A/132A Only) 1 Set the Pulse Generator to the following: 2 Connect the equipment as shown in Figure Pulse Generator Figure 1-3.External Arm Test Setup (HP 53131A/132A Only) Set the HP 8663A to output a 200 MHz, 100 mV sine wave signal to Channel On the Counter, Press Run key Send a single pulse by pressing the MAN key on the HP 8130A, and observe that with each press the Gate annunciator flashes 1 MHz External Timebase Input (HP 53131A and HP 53181A Only) 1 Connect the equipment as shown in Figure Figure 1-4.External Timebase Test Setup 2Cycle the POWER key to preset the Counter Set Synthesizer #1 (i.e., the HP 3325B connected to the 5 MHz External Timebase Input (HP 53131A and HP 53181A Only) Change the frequency of Synthesizer # 1, which is connected to the Counter’s 2On the Counter, press Run key 10 MHz External Timebase Input (HP 53131A and HP 53181A Only) Change the frequency of Synthesizer #1, which is connected to the Counter’s 10 MHz External Timebase Input for the HP 53132A 1Connect the equipment as shown in Figure Set Synthesizer #1 (i.e., the HP 3325B that is connected to the Mark Pass or Fail in the HP 53131A/132A Performance Test Record on 5Disconnect the test setup HP 53131A/132A Complete Performance Tests The specifications of the HP 53131A/132A Universal Counter can be Record the results of the performance tests in the appropriate place on HP 53131A/132A Performance Test Record, which starts on page Page Connect the pulse generator signal to Channel 1 of the Counter as shown in HP53131A/132Pulse Generator Figure 1-5.Time Interval (Channel 1 TO 2) Test Setup 2 Set the Pulse Generator to the following: 3On the Counter, Press Single/Stop key Test 2: Trigger Level (HP 53131A/132A Only) 2Set CHANNEL 1 input conditions to: Trigger/Sensitivity, LEVEL: 0.000V 50Ω/1MΩ, 50Ω 3Set CHANNEL 2 input conditions to: Connect the output of the HP 3325B to Channel 1 of the Counter as shown in HP 53131A/132A Synthesizer Figure 1-6.Trigger Level Test Setup 2Set the HP 3325B to output a 1 MHz, 80 mVp-psquare wave signal 3Set the HP 3325B DC OFFSET to −60 mV Page Page 100 kHz to 100 MHz Sensitivity for HP 53131A/132A Figure 1-7.Channels 1 and 2 Frequency Sensitivity Test Setup 2Set the HP 8663A Signal Generator to output a 100 MHz −35.0 dBm sine wave signal (−20.0 dBm for Option 060 Rear Terminals) to the Counter’s Channel 1 input 3On the Counter, press Run key In 0.1 dB steps, increase the power level until the Counter displays a 100 MHz to 200 MHz Sensitivity for HP 53131A/132A Increase the power level by 0.1 dB steps until the Counter displays a 4Sweep the signal generator frequency from 200 MHz to 100 MHz 5Record the actual reading in the Performance Test Record (Test 3, Line 3) 6Connect the signal generator to Channel 8Repeat steps 1 through 4 for Channel 9Record the actual reading in the Performance Test Record (Test 3, Line 4) 200 MHz to 225 MHz Sensitivity for HP 53131A/132A 4Sweep the signal generator frequency from 225 MHz to 200 MHz 5Record the actual reading in the Performance Test Record (Test 3, Line 5) Test 4: Channels 1 and 2 Frequency Accuracy (HP 53131A/132A Only) 2Using the Gate & ExtArm key, set the gate time to TIME 1.000 s Figure 1-8.Channels 1 and 2 Frequency Accuracy Test Setup 2Set the Signal Generator to output 1 MHz at −7 dBm Change the signal generator frequency to 100 MHz Change the signal generator frequency to 200 MHz Change the signal generator frequency to 225 MHz 11Connect the signal generator to Channel 12On the Counter, press Freq & Ratio key until Frequency 1 is displayed Test 5: Option 030/050/124 Channel 3 Frequency Sensitivity (HP 53131A/132A Only) 2Set the Counter as follows: Freq & Ratio, FREQUENCY 100 MHz to 2.5 GHz Sensitivity for HP 53131A/132A Option 030 only 2.7 to 3.0 GHz Sensitivity for Option 030 only 200 MHz to 5.0 GHz Sensitivity for HP 53131A/132A (Option 050 only) 200 MHz to 12.4 GHz Sensitivity for HP 53131A/132A (Option 124 only) Test 6: Option 030/050/124 Channel 3 Frequency Accuracy Freq & Ratio, FREQUENCY Gate & ExtArm, TIME: TIME 1.000 s 1Connect equipment as shown in Figure (NOTE: For Options 050 and 124, skip steps 2 through 5. Proceed to step 6.) Set the HP 8340B to output 3.0 GHz at Set the HP 8340B to output 5.0 GHz at 10Set the HP 8340B to output 12.4 GHz at −17 dBm. (This step is for Option 124 only.) Test 7: Peak Volts, Channels 1 and 2 (HP 53131A/132A Only) 2Press Other Meas key until VOLT PEAKS 1 is displayed 3Set CHANNEL 1 input to: 50Ω/1MΩ, 50Ω 4Set CHANNEL 2 input to: HP 53131A/132ASynthesizer Figure 1-10.Peak Volts Test Setup 2Set the HP 3325B to output a 2 MHz, 2 Vp-psine wave Record the actual reading in the Performance Test Record (Test 7, Line 1a) Record the actual reading in the Performance Test Record (Test 7, Line 1b) Remove the signal from Channel 1 of the Counter and connect it to Channel Press Other Meas key until VOLT PEAK 2 is displayed (Test 7, Line 2a) (Test 7, Line 2b) HP 53131A/132A HP-IBVerification Program (Optional) Load “VER31” RUN 2Follow the instructions displayed in the computer’s screen After running this program, record the result (Pass or Fail) on the last page HP 53131A/132A Performance Test Record (Page 1 of 6) HP 53131A/132A Performance Test Record (Page 2 of 6) HP 53131A/132A Performance Test Record (Page 3 of 6) HP 53131A/132A Performance Test Record (Page 4 of 6) HP 53131A/132A Performance Test Record (Page 5 of 6) HP 53131A/132A Performance Test Record (Page 6 of 6) HP 53181A Complete Performance Tests HP 53181A Frequency Counter place on HP 53181A Performance Test Record, which starts on page Table 1-3.The HP 53181A Performance Tests Test 1: Trigger Level (HP 53181A Only) 2Set CHANNEL 1 input condition to: HP 53181ASynthesizer Figure 1-11.Trigger Level Test Setup Page Test 2: Channel 1 Frequency Sensitivity (HP 53181A Only) 100 kHz to 100 MHz Sensitivity for HP 53181A Figure 1-12.Channels 1 Frequency Sensitivity Test Setup Set the HP 8663A Signal Generator to output a 100 kHz Channel 1 input Sweep the frequency from 100 kHz to 100 MHz For Option 060, sweep frequencies from 100 kHz to 225 MHz 5Record the actual reading in the Performance Test Record (Test 2, Line 1) 100 MHz to 200 MHz Sensitivity for HP 53181A 1Change the signal generator settings to 110 MHz at −30 dBm 3Sweep the signal generator frequency from 100 MHz to 200 MHz 4Record the actual reading in the Performance Test Record (Test 2, Line 2) 200 MHz to 225 MHz Sensitivity for HP 53181A Test 3: Channel 1 Frequency Accuracy (HP 53181A Only) 2Using the Gate & ExtArm key, set gate time to TIME 1.000 s Page Page Test 4: Option 015/030/050/124 Channel 2 Frequency Sensitivity 100 MHz to 1.5 GHz Sensitivity for Option 015 Only Increase the power level in 1 dB steps until the Counter reads 500 MHz Sweep the frequencies from 100 MHz to 1.5 GHz (Test 4, Line 1) 100 MHz to 2.7 GHz Sensitivity for Option 030 Only 2.8to 3.0 GHz Sensitivity for Option 030 Only 200 MHz to 5.0 GHz Sensitivity for Option 050 only 200 MHz to 12.4 GHz Sensitivity for Option 124 only Test 5: Option 015/030/050/124 Channel 2 Frequency Accuracy (HP 53181A Only) 100 MHz to 1.5 GHz Accuracy Test for Option MEASURE/Freq & Ratio, FREQUENCY Page Test 5: Option 015/030/050/124 Channel 2 Frequency Accuracy (HP 53181A Only) Change the synthesized signal generator’s frequency to 1.5 GHz Record the actual reading in the Performance Test (Test 5, Line 2) Minimum to Maximum Accuracy Test for Options 030/050/124 Page Page Page Figure 1-16.Peak Volts Test Setup Record the actual readings in the Performance Test Record (Test 6, Line a) Record the actual readings in the Performance Test Record (Test 6, Line b) 3Disconnect the test setup HP 53181A HP-IBVerification Program (Optional) Load “VER81” HP 53181A Performance Test Record (Page 1 of 4) HP 53181A Performance Test Record (Page 2 of 4) HP 53181A Performance Test Record (Page 3 of 4) HP 53181A Performance Test Record (Page 4 of 4) Page Returning the Instrument to About the HP 53131A/132A Calibration Menu The HP 53131A/132A Calibration Procedures About the HP 53181A Calibration Menu The HP 53181A Calibration Procedures Returning the Instrument to Hewlett-Packardfor Service To Provide Repair Information 1Write the following information on a tag: 2Attach the tag to the instrument 3Pack the instrument To Pack in the Original Packaging Materials 3Make sure one of the polystyrene block is in its proper position in the box 4Place the instrument, front panel end first, on the polystyrene block 7Seal the shipping container securely To Pack in the Commercially Available Materials Wrap the instrument in heavy paper or plastic Place the instrument in a strong shipping container Protect the control panel with cardboard Add a layer of shock-absorbingmaterial About the HP 53131A/132A Calibration Menu Overview of the HP 53131A/132A Calibration Menu Scale & Offset CAL SECURE CAL UNSECURE) CAL: OFFS 1 / 2 GAIN 1 / 2 CAL: TI QUIK The HP 53131A/132A Calibration Menu Tree key to access this menu. This menu does not exist in early versions (firmware revisions 3317, 3335, and 3402) of the HP 53131A/132A In the early versions of the Counter, the CAL: menu item resides in the Utility menu, and there is no calibration security CAL UNSECURE 1Press and hold Scale & Offset key, then cycle POWER key 2Press Scale & Offset key until CODE: is displayed Press the appropriate arrow keys to enter the security code “ CAL UNSECURE is displayed Press any one of the arrow keys until your calibration choice (that is CAL: OFFS2 CAL: GAIN 1 CAL: GAIN 2 CAL: TI QUIK Notes Pertaining to CAL: TI QUIK Advantage: Disadvantage: Input signal: Timebase: Equipment and Counter Setup: See Figure Figure 2-1.Calibration Setup for CAL: TI FINE Out of HP 8130A, into HP 59992A J06 Calibrator Signal: Press and hold Scale & Offset key, then cycle POWER key Press Scale & Offset key until CODE: is displayed Press the appropriate arrow keys to enter the security code, then press Enter key To Change to a New Security Code 2Press Scale & Offset key until CAL COUNT? is displayed Press any one of the entry keys (arrow 2Press Scale & Offset key until HELP: CAL? is displayed 3Press any one of the arrow keys until your help choice (that is HELP: CAL?, HELP: SECURE?, HELP: CODE?) is displayed The HP 53131A/132A Calibration Procedures Press and hold Recall (Utility) key, then cycle POWER key REV: n then perform the calibration procedures in Chapter 6, “Backdating.” 3 Press the appropriate arrow keys to enter the security code Press g key four times Press d key five times Press g key once, and then press d key three times Press g key once, and then press d key once display OFFS 1 PASS To calibrate Channel 2, press any one of the arrow keys until CAL: OFFS 2 ? is displayed is displayed display OFFS 2 PASS To Calibrate the Gain for Channels 1 and 1Press any one of the arrow keys until CAL: GAIN 1 ? is displayed 2Press Enter key 3Connect a BNC tee connector to Channel 1 of the Counter Connect the Counter, dc power supply, and digital multimeter as shown in To calibrate the gain for Channel 2, connect the input or the BNC Tee to Channel 2 of the Counter Press any one of the arrow keys until CAL: GAIN 2 ? is displayed Press Enter key again display GAIN 2 PASS CAL: TI QUIK? Calibration 1Press any one of the arrow keys until CAL: TI QUIK? is displayed HP53131A/132A Pulse Generator Figure 2-3.Calibration Setup for CAL: TI QUIK 4Set the HP 8130A as follows: PERIOD: 100 ns TI CAL PASS 6Disconnect the calibration setup CAL: TI FINE? Calibration Figure 2-4.Calibration Setup for CAL: TI FINE 2 Set the HP 8130A as follows: 3 Press any one of the arrow keys until CAL: TI FINE? is displayed Note the Counter display message prompts you to press buttons on the HP 59992A J06 Calibrator for each part of a four-part calibration House Standard 10 MHz Reference Figure 2-5.Standard Timebase Calibration Setup With an insulated tuning tool, turn the OSC Adjust To Calibrate the High Stability Timebase Option (Medium, High, or Ultra-High) Allow the Counter to warm up for approximately 24 hours before performing this calibration 1 Connect the output of a 10 MHz house standard to Channel 1 of About the HP 53181A Calibration Menu Overview of the HP 53181A Calibration Menu CAL: OFFS 1?, GAIN 1 Page The HP 53181A Calibration Menu Tree BAD CODE Press the appropriate arrow keys to enter the security code, then press To Change to New the Security Code The HP 53181A Calibration Procedures To Calibrate the Offset for Channel 3Press the appropriate arrow keys to enter the security code a.Press key four times b.Press key five times key once, and then press key three times key once key eight times 4Press Scale & Offset key until CAL: OFFS 1 ? is displayed To Calibrate the Gain for Channel 2Press Enter key key 3Connect a BNC tee connector to Channel 1 of the HP 53181A 4Connect the Counter, dc power supply, and digital multimeter shown in Figure 8Disconnect the calibration setup Figure 2-7.Standard Timebase Calibration Setup Page Pre-TroubleshootingInformation Safety Considerations Recommended Test Equipment Repair Considerations Electrostatic Discharge ENSURE that DO NOT wear clothing subject to 4DO NOT handle components or assemblies in carpeted areas After Service Considerations Product Safety Checks RESISTANCE CHECKS DESCRIBED IN THE FOLLOWING TEXT REQUIRE THAT THE POWER CORD BE CONNECTED TO THE INSTRUMENT AND THAT AC POWER BE DISCONNECTED Assembly Identification and Location Table 2-1.HP 53131A Assembly Identification Table 2-2.HP 53132A Assembly Identification Table 2-3.HP 53181A Assembly Identification Figure 2-8A.Instrument Top Internal View Figure 2-8B.Instrument Top Internal View (Option 002) Troubleshooting the Counter Power Supply Check HAZARDOUS VOLTAGES ARE ON THE POWER SUPPLY ASSEMBLY. ONLY SERVICE TRAINED AND QUALIFIED PERSONNEL SHOULD PERFORM THE FOLLOWING OPTIONS Table 2-4.A4 AC Power Supply Voltages Overview of the Self-TestRoutines TEST LOOP: ON OFF TST PRINT: ON ALL DISP TEST LOOP: CPU INTERP KEYPAD PRINT Diagnosing the Faulty Assembly by Using the Self Tests To Run the Individual Self Tests Press Recall (Utility) key until TEST LOOP: is displayed Ensure that TEST LOOP:OFF is displayed TEST LOOP: is ON TEST LOOP to OFF 8Repeat steps 2 through 5 for each of the self tests Figure 2-11A.HP 53131A/132A Self Test Troubleshooting Setup Figure 2-11B.HP 53181A Self Test Troubleshooting Setup FAIL Table 2-5.Troubleshooting Page Page Tools Required 1Turn Counter off 2Remove ac line power cord from the rear ac line socket To Remove the Cover WHEN THE COVER IS REMOVED FROM THE INSTRUMENT LINE VOLTAGES ARE EXPOSED WHICH ARE DANGEROUS AND MAY CAUSE SERIOUS INJURY IF TOUCHED. DISCONNECT POWER Page Page Page Page Page Page Page 6Remove A2 Display Assembly from the front bezel Now, remove the POWER key cap by gripping and pulling it As shown in Figure 3-7, the rubber keypads (MP6) are now free Just pull them out of the bezel Remove the window (MP5), shown in Figure 3-7,by pressing down Page Page Page Page Page Page Page Page To Remove the Rear Terminals (Option 060) 2 Unsolder the lead-endof the cables from their appropriate ground and input pads on the A1 Motherboard Assembly (J16, J17) as shown in Figure INPUTS Figure 3-13.Rear Terminals (Option 060) Removal Page Page Page Page To Retrofit A3 1.5/3.0/5.0/12.4 GHz Channel Assembly (Option To Retrofit A5 DC Power Input Assembly (Option 002) Option 002 DC Power Input Assembly Parts Item Qty Preliminary Procedure Retrofitting Procedure Page Page Page Figure 4-1D.DC Power Input Assembly Retrofitting Page To Retrofit A6 High Stability Timebase Assembly (Options 001, 010, and Option 001 Medium Stability Timebase Assembly Parts *Option 010 High Stability Timebase Assembly Parts *Option 012 Ultra-HighStability Timebase Assembly Parts Page Page Option 060 Rear Terminals Parts rear terminals only front terminals only Figure 4-3A.Plug Removal for Rear Terminals Retrofitting 2 for HP 53181A) as shown in Figure 4-3B Figure 4-3B.Rear Terminals Retrofitting Insert the connector-endof the W1, with the washers (H6) in place on the connector, through the appropriate rear INPUTS opening Insert and tighten the BNC nuts (H3) to secure the coaxial cables to the rear of the chassis Solder the lead-endof the cables to their appropriate ground and Page Page Table 5-1.Exchange Assemblies Reference Designations How To Order A Part Parts Identification Contacting Hewlett-Packard By telephone: For mail correspondence, use the address below: Cabinet Parts and Hardware Table 5-2.Reference Designation Table 5-3.HP 53131A/132A/181A Replaceable Parts Table 5-3.HP 53131A/132A/181A Replaceable Parts (continued) Figure 5-1.HP 53131A/132A/181A Exploded View (Chassis Parts and Assemblies) Table 5-3.HP 53131A/132A/181A Replaceable Parts (Continued) Table 5-4.Manufacturer’s Code List Page Table 6-1.Instrument this Guide Directly Applies To Backdating Hardware CHANGE 1 (Below Series Prefix 3711A) CHANGE 2 (New A3 5/12.4 GHz Prescaler Assembly) CHANGE 3 (New TCXO boards) b.Connect the negative lead of a voltmeter to the white wire CHANGE 4 (Series 3710A to 3705A) CHANGE 5 (Series 3705A to 3546A, 3548A) CHANGE 6 (Below Series Prefix 3416A) CHANGE 7 (Below Serial Number 3349A01906) CHANGE 8 (Below Serial Prefix 3404A) Backdating Firmware CHANGE 1 (Firmware Revisions 3317, 3335, 3402, 3427) Replace Recall (CAL: OFFS 1 / 2 ?, GAIN 1 / 2 ?, TIMEBAS ?, and TI 1⊕2?) About the HP 53131A Calibration Menu (Continued) The HP 53131A Utility/Calibration Menu Tree Utility The HP 53131A Calibration Procedures CHANGE 1 (Firmware Revisions 3317, 3335, 3402, 3427) (Continued) To access the Utility menu, power down, and press and hold the 2Press Recall (Utility) key until CAL: OFFS 1 ? is displayed 3Press Enter key 4Connect the Counter, dc power supply, and multimeter as shown in Figure Figure 2-1.Gain Calibration Setup 5Adjust the power supply until the multimeter displays + 5.000 V ± 0.001 9Press any one of the arrow keys until CAL: GAIN 2 ? is displayed 10Press Enter key 11Press Enter key again GAIN 2 PASS 12Disconnect the calibration setup Equipment HP53131APulse Generator Figure 2-3.TI Calibration Setup 4 Set the HP 8130A as follows: 6 Disconnect the calibration setup Figure 2-4.Standard Timebase Calibration Setup (Medium or High) Allow the Counter to warm up for approximately 30 minutes before performing this calibration 2Press any one of the arrow keys until CAL: TIMEBAS? is displayed 4Press Enter key after each instruction Backdating Specifications CHANGE 1 (53131A, Serial Prefix 3710A and Below) CHANGE 2 (53132A, Serial Prefix 3546A and Below) CHANGE 3 (53181A, Serial Prefix 3711A02841 and Below) Page Page Page Instrument Inputs (Continued) Time Base Measurement Specifications Measurement Specifications (Continued) Page Frequency Measurement Example: Page Page Page Measurement Definitions Measurement Definitions (Continued) Measurement Definitions (Continued) Measurement Arming and Processing Measurement Arming and Processing (Continued) Measurement Arming and Processing (Continued) General Information Page Page Page Page Page Page Page Page Page Page Page Page Index NUMERICS

• To Remove the Cover		page 3-4
• To Remove the Front Bezel		page 3-6
• To Remove A1 Motherboard Assembly		page 3-9
• To Remove the A2 Display Board, Keypads, and Window		page 3-11
• To Remove A3	1.5/3.0/5.0/12.4 GHz Channel Assembly	page 3-13
(Option 015/030/050/124)
• To Remove A4 AC Power Supply Assembly		page 3-15
• To Remove A5	DC Power Input Assembly (Option 002)	page 3-17
• To Remove A6	High Stability Timebase Assembly	page 3-19
(Options 001, 010, and 012)
• To Remove the Rear Terminals (Option 060)		page 3-21