LAT Integration and Test

1
MRB NCR 562 Bay 0 and 4 TPS Removal and
Replacement

• LAT Integration and Test
• and Systems Engineering

2
Recommendation

• Option 3 TPS Removal
• Allows repair of TPS
• Minimizes risk of damage to Flight Hardware
• ELX has recalibration method for TEM/TPS
  telemetry
• Accurate shim determination requires TPS or
  TPS/TEM/CAL measurement
• TPS height and flatness data will be used to
  determine offset
• TPS selection determined by best fit for shim,
  then ELX criteria
• TEM or TEM/CAL could be removed if TPS data fails
  to meet criteria

3
Options

• Options 1 through 5 are discussed in subsequent
  charts
• Option 1 Use As Is
• Option 2 TPS Removal and Rework
• Option 3 TPS Removal
• Option 4 TEM/TPS Removal
• Option 5 CAL/TEM/TPS Removal

4
Option 1 Use-As-Is

• IT Mechanical Pros
• No demate of flight connections
• No change to accurately measured CAL/TEM/TPS
  stack height
• IT Mechanical Cons
• None
• IT Electrical Pros
• No additional testing required
• IT Electrical Cons
• None
• ELX Pros
• No immediate change to TEM/TPS calibration or
  performance
• ELX Cons
• Power supply circuit design is marginally stable
  with temperature
• 2 different TPS configurations within the LAT
• Potential Risks
• Power supply oscillation could negatively impact
  detector performance
• Power supply oscillation could worsen over
  temperature and time
• Rework later in the program could increase risk.
• Discussion

5
Option 2 TPS Removal and Rework

• IT Mechanical Pros
• Demate TPS/TEM connection in Grid Low Risk
• Demate TPS/PDU connection in Grid Low Risk, but
  connector jack screw may loosen
• Maintains CAL/TEM/TPS stack height
• IT Mechanical Cons
• None
• IT Electrical Pros
• Maintains TEM/TPS telemetry calibration
• Maintains calibration of Tracker and Calorimeter
  detectors
• IT Electrical Cons
• Need regression test definition to validate
  re-assembled TEM/TPS in the grid
• ELX Pros
• Permits rework of TPS for power supply
  oscillation
• Maintains TEM/TPS telemetry accuracy
• Maintains TEM/TPS Performance
• ELX Cons
• Testing of removed TPS required
• Potential Risks
• Impact to IT schedule while TPS is reworked and
  retested

6
Option 3 TPS Removal

• IT Mechanical Pros
• Good access to the interface between TEM and TPS
• Shimming may not be required if TPS box height
  meets criteria
• Demate TPS/TEM connection in Grid Low Risk
• Demate TPS/PDU connection in Grid Low Risk, but
  connector jack screw may loosen
• IT Mechanical Cons
• Stack height measurement is invalidated and
  becomes inferred
• If shimming is required it is a more complex
  operation to loosen and shim at the CAL interface
• IT Electrical Pros
• None
• IT Electrical Cons
• Requires recalibration of TEM/TPS telemetry
• Need regression test definition to validate new
  TEM/TPS Assembly in the grid
• Requires recalibration of Tracker and Calorimeter
  detectors
• ELX Pros
• Permits rework of TPS for power supply
  oscillation
• ELX Cons
• Degradation in TEM/TPS telemetry accuracy
• TEM/TPS measured performance becomes inferred

7
Option 3 TPS Removal (contd)

• Potential Risks
• Unknown where or how shimming will be performed,
  if required
• Shimming in the Grid has not been demonstrated.
• Discussion
• 18 TPS units have measured flatness variation
  within 1 mil
• 17 TPS units have measured height variation
  within 4 mils
• Height was not measured for TPS units currently
  installed in Bays 0 GLAT1749 sn 22 and 4
  GLAT1750 sn 03
• GLAT1749 and GLAT1750 height and flatness would
  be measured after removal
• GLAT1813 sn 11 and GLAT1828 sn 02 height and
  flatness would be measured prior to installation
• Height variance of measured TPS chassis is 0.004
• Flatness variance of TPS measured chassis is 0.001

8
Option 3 TPS Removal (contd)

• Discussion (contd)
• Suggested re-calibration method for new assembled
  units
• CAL and TKR HV Bias Currents
• Maintain the slope constants for both CAL and TRK
  Bias currents.
• Re-calibrate the intercept constants by taking
  current average of one thousand measurements
  before and after TPS replacement, and then adjust
  the new average measurement to old reading with
  new value of Intercept point.
• For Total TEM/TPS current
• Re-calibrate the slope and intercept constants by
  taking the average of one thousand measurements
  before and after replacement of TPS in
  conditions    - no TRK or CAL FE is powered   
  - CAL FE is powered and TRK FE is not    - TRK
  FE is powered and CAL FE is not    - TRK and CAL
  FE is poweredThese four points allow make it
  easy to make fit and find new calibration
  constants for new assembly.Telemetry points can
  be verified by recording external PS current
  reading for all 4 points before and after
  replacement.

9
Option 3 TPS Removal (contd)

• RR of TPS Basic Steps
• Measure relative height of TEM/TPS assembly to
  CAL base plate in the GRID.
• Remove TPS from TEM on CAL in GRID.
• Measure height of TPS removed from GRID on
  granite table.
• Measure new power supply on granite table.
• Determine new shim thickness.
• Install new shims.
• Install new TPS.
• Verify relative height obtained in step 1.

10
Option 3 TPS Removal (contd)

• TPS Replacement IT Risk Summary

Risk Description Weight Factor (1-5) Risk (1-3) Score Mitigation Plan
Demate and mate of new TPS to TEM connector. 4 2 8 Dry run assembly procedure
If shimming is required it is a more complex operation to loosen and shim at the CAL interface 4 3 12 Demonstrate with EM units in 1x4.
Regression Testing to Validate 2 2 4 Utilize existing single tower tests
Total 24
If shimming is not required the overall risk
score is reduced by 12 pts.
11
Option 4 TEM/TPS Removal

• IT Mechanical Pros
• Demate TPS/TEM connection outside Grid Low Risk
• Demate TPS/PDU connection in Grid Low Risk, but
  connector jack screw may loosen
• Exposes existing shimming interface between
  TEM/CAL
• Shimming operation is cleaner and consistent with
  technique used in the metrology bay. Needs
  pathfinding.
• Installation of thermistor cable is simplified
  with the box removed.
• IT Mechanical Cons
• Re-shimming required
• Requires new in Grid shimming procedure
• Demate 8 TEM/TKR flex cables in Grid Elevated
  Risk, EXTREMELY LOW Risk Tolerance
• Demate 4 Calorimeter flex cables in Grid
  Elevated Risk
• IT Electrical Pros
• None
• IT Electrical Cons
• Need regression test definition to validate new
  TEM/TPS Assembly in the grid
• Requires recalibration of Tracker and Calorimeter
  detectors

12
Option 4 TEM/TPS Removal (contd)

• ELX Pros
• Permits rework of TPS for power supply
  oscillation
• No degradation in TEM/TPS telemetry accuracy
• TEM/TPS performance is based on measurements
• ELX Cons
• None
• Potential Risks
• Shimming in the Grid has not been demonstrated
• Requires demate of TEM/TKR flex cables that could
  require extensive TKR rework if damaged. There
  are no spares.
• Requires demate of TEM/CAL cables.

13
Option 4 TEM/TPS Removal (contd)

• RR of TEM/TPS - Basic Steps
• Measure relative height to CAL base plate of
  TEM/TPS assembly in GRID.
• De-mate CAL, TKR, TEM to GASU, and TPS to PDU
  cables from TEM/PSU assembly.
• Remove TEM/TPS from CAL in GRID.
• Measure height of TEM/TPS removed from GRID on
  granite table.
• Measure new TEM/TPS on granite table.
• Determine new shim thickness based on the height
  differences between the removed and replacement
  assemblies.
• Install new TEM/TPS with shim stack up determined
  in previous step.
• Verify relative height obtained in step 1.
• Install thermistor cable.
• Mate CAL, TKR, TEM to GASU, and TPS to PDU
  cables to the newly installed TEM/TPS assembly

14
Option 4 TEM/TPS Removal (contd)

• TEM/TPS Replacement IT Risk Summary

Risk Description Weight Factor (1-5) Risk (1-3) Score Mitigation Plan
Requires breaking flight connections to CAL, TKR, GASU and PDU connections (13 Connectors). 5 3 15 Proceed cautiously. Do not use excessive force for mate or demate.
Re-shimming Required 4 2 8 Demonstrate with EM units in 1x4.
Regression Testing to Validate 2 1 2 Utilize existing single tower tests
Total 25
15
Option 5 CAL/TEM/TPS Removal

• IT Mechanical Pros
• Demate TPS/TEM connection outside Grid Low Risk
• Demate TPS/PDU connection in Grid Low Risk, but
  connector jack screw may loosen
• Permits accurate CAL/TEM/TPS shimming in
  metrology bay
• IT Mechanical Cons
• Demate 8 TEM/TKR flex cables in Grid Elevated
  Risk, EXTREMELY LOW Risk Tolerance
• Demate 4 Calorimeter flex cables outside Grid
• Removal of installed shear plates for Bays 0 and
  4 may not be desirable with existing nut failure
  (NCR 579)
• IT Electrical Pros
• TEM/TPS regression testing could be performed
  outside of Grid
• Permits TEM/CAL re-calibration in metrology bay
• IT Electrical Cons
• Requires re-calibration of TKR detector in Grid
• ELX Pros
• Permits rework of TPS for power supply
  oscillation
• No degradation in TEM/TPS telemetry accuracy
• TEM/TPS performance is based on measurements
• ELX Cons
• None

16
Reference

• Completed Action Items From Previous MRB
• COMPLETE - QA identify which TPS chassis s/n are
  installed and to be installed.
• TPS TPS/TEM ASSY TPS CHASSIS Height
• GLAT1749 GLAT1752 LAT-DS-00995-51-22 Not
  measured
• GLAT1750 GLAT1753 LAT-DS-00995-51-03 N
  ot measured
• GLAT1813 GLAT1832 LAT-DS-00995-51-11 3
  .0618
• GLAT1828 GLAT1845 LAT-DS-00995-51-02
  3.0597
• COMPLETE - SE Assess impact of TPS swap based on
  chassis dimensions with inputs from IT and M.
  Nordby.
• See Recommendation
• Only 19 of the 23 TPS chassis were measured.
• Flatness data variance of 19 boxes is .001
• Height data variance of 18 boxes is .004
• IT and M. Nordby will attend MRB.
• COMPLETE QA How were TPS chassis heights
  measured?
• The measured TPS units were measured on the CMM
  (Coordinate Measurement Machine). The height
  measurement of 3.060 0.005 was measured by the
  CMM's gaussian best fit plane. The part was
  constrained to the granite table per drawing
  instructions for parallelism. The TPS units were
  measured for a 0.010" parallelism free state
  condition, there were a few close to the limit,
  but not out of tolerance. The parallelism
  measurement was performed with an indicator and
  height gage.
• COMPLETE (See presentation) - IT assess
  feasibility of performing height measurements in
  Grid for all options.
• COMPLETE (See presentation) - IT assess
  shimming in Grid shimming for all options.
• COMPLETE - ELX identify candidate TPS for
  installation in to Bays 0 and 4
• Suggestion is to use for TPS  replacement on 
  tower A and B the following units1. GLAT1813
  TPS from Assembly GLAT1832 should replace TPS 
  GLAT1749 from  assembly GLAT1752 2. GLAT1828 TPS
  from Assembly GLAT1845 should replace TPS 
  GLAT1750 from  assembly GLAT1753.

17
Reference

• COMPLETE - ELX identify candidate TPS for
  installation in to Bays 0 and 4
• Suggestion is to use for TPS  replacement on 
  tower A and B the following units
• 1. GLAT1813 TPS from Assembly GLAT1832 should
  replace TPS  GLAT1749 from  assembly GLAT1752
• 2. GLAT1828 TPS from Assembly GLAT1845 should
  replace TPS  GLAT1750 from  assembly
  GLAT1753.Selection of these units are based on
  similarity of HV calibration constants

18
Reference

• Bay 0 GLAT1813 -gt GLAT17491752 (TPS GLAT1749)

Calibration Date Slope Intercept
CAL Bias Current 2/2/05 0.930382662178 -0.0014032780581
TKR Bias Current 2/2/05 0.935558213381 0.00234355041672
TEM/TPS Current 2/2/05 66.973583 -1.518328

• 1832 (TPS GLAT1813)

Calibration Date Slope Intercept
CAL Bias Current 5/9/05 0.917697111398 0.000884641517652
TKR Bias Current 5/9/05 0.937436903933 0.0211388061165
TEM/TPS Current 5/9/05 66.993715 -0.837730
19
Reference

• Bay 4 GLAT1828 -gt GLAT1750 
• 1753 (TPS GLAT1750)

Calibration Date Slope Intercept
CAL Bias Current 1/31/05 1.05784628111 0.00439458111717
TKR Bias Current 1/31/05 0.930910460477 -0.0122075240151
TEM/TPS Current 1/31/05 66.510847 0.064750

• 1845  (TPS GLAT1828)

Calibration Date Slope Intercept
CAL Bias Current 5/9/05 1.00367085354         -0.00551484961688
TKR Bias Current 5/9/05 0.956402741661 0.00380408724678
TEM/TPS Current 5/9/05 66.388597 0.089839
20
Reference

• NCR 562 - TPS CCAs on GLAT 1752 and GLAT 1753
  TEM/TPS assys have not been reworked per NCR 397
  to correct observed oscillation of CAL 3.3V
  digital. Assemblies were integrated onto the
  Grid before the problem was observed in TEM/TPS
  test data
• From Parent NCR 397
• Description of Non Conformance
• Oscillation of CAL-3.3V Digital when TEM/TPS
  tester board is connected. Amplitude was found
  around 100mV, 1-2 KHz frequency.
• Oscillation is triggered at power-on of
  calorimeter and sustained. No oscillation is
  present when turning the power on at cold
  temperatures (-40C). At room-temperature
  oscillation might or might not be triggered by
  power-on. At hot temperatures (50C) oscillation
  was always triggered at power-on. Whether or not
  the oscillation is triggered at power-up, is
  dependant of the temperature at power-up. If the
  temperature of the module is changed after power
  up, the presence of oscillation (or not) is
  maintained and is independent of whether the
  temperature is changed.
• Test showed that the supply only oscillates with
  loads drawing around/more than 1.2A. It does not
  oscillate at loads of around 600mA (the CAL has
  lt1A). In addition it appears to only oscillate
  when capacitive loads are added in parallel to
  the resistive loads.
• No oscillation was observed at the TPS-only test.
  That tester includes tests at 150 of the cal
  nominal load, but does not have capacitive loads
  in parallel. It is not clear whether the problem
  is present when CAL AFEE boards are connected. It
  is known that on tower A and B the TPS system is
  stable at room-temperature.
• Dispositions
• (Cullinan, 4/5/05) Per MRB discussion 4/1/05 and
  4/4/05, the following rework on the qual TPS
  board is underway on AIDS 974 to resolve the
  oscillation issue observed
• 1. Conformal coating on board in areas adjacent
  to CAL resistors R53, R58, TKR resistors R122,
  R142, R61, TEM resistor R20, R50 has been removed
  using wooden stick in preparation for attaching
  capacitors to be connected in parallel with these
  resistors, per direction from G. Haller. Caps
  will use 30 gauge wire pigtails to connect to on
  board resistors. Caps CDR33BX473AKUS will be
  used in this application. Caps will be bonded to
  board using Hysol EA9394.

21
Reference

• NCR 562 (contd)
• 2. On board CAL resistors R28, R25, R51, R52
  will be removed and replaced with 2.74KOhm
  resistors M55342K06B2E74R per G. Haller
  direction.
• 3. On board Compensation Capacitors C531, C532
  (CAL bias) and C631, C632, C633 (TKR bias) have
  present value of 10pF. Remove and replace these
  caps with 100pF caps (on TPS CCA parts list), P/N
  CDR31BP101BKUS.
• Dispo 2 (Cullinan, 4/7/05) Rework was completed
  4/6/05 and the qual TPS board was tested on the
  TPS tester and connected to the AFEE/MCMs and
  tested up to 75 deg. C. Per G. Haller,
  oscillation was not observed with simulated load
  of greater than 150 of expected TKR load.
  Oscillations were noted on high voltage when
  simulated load was approx. 250 of expected TKR
  load. MRB was held 4/7/05. In attendance were
  Haller, Sapozhnikov, Hascall, Bright, Klaisner,
  Cullinan, Bloom, J. Lohr, B. Graf, N. Johnson to
  discuss test results. MRB concurred that testing
  performed to date was sufficient to validate new
  qual TPS board configuration and the elimination
  of the oscillation within TPS performance
  requirements.
• Additional TPS board testing will be completed
  4/7/05. All testing will be performed to AIDS
  974, with data packages attached to this AIDS.
  Qual TPS board will be reinstalled into TPS base.
  Thermal compound CV-2946 will not be used (SLAC
  does not have material on hand) between board and
  TPS base. Analysis by DAQ showed temperature
  rise of TPS board was approximately 3-4 deg C
  without the thermal compound. Also, areas where
  conformal coating was removed and newly added
  pigtailed capacitors will not be covered with
  Arathane conformal coating at this time. In
  addition, all screws securing the TPS board into
  the TPS base, securing the TPS lid, and securing
  the TPS to the TEM will not be staked with Hysol
  0151. These materials are not immediately
  available at SLAC. Need for qual TEM/TPS for
  testing at NRL is urgent and the qual TPS board
  can be used for NRL testing in this
  configuration. When Qual TEM/TPS is returned to
  SLAC, the TPS will be reassembled to include
  these materials to return the unit to meet the
  assembly drawing.
• MRB also discussed the plan to document these
  configuration changes. Relevant TPS assembly
  drawings, schematics and BOMs will need to be
  revised. Report list of documents that will be
  revised to this NCR once list is compiled.

22
Reference

• NCR 562 (contd)
• MRB also concurred to rework remaining TPS boards
  at SLAC prior to pre-conformal coat performance
  testing and thermal cycle testing. The CCAs will
  arrive from General Technology and will be
  reworked per this NCR and AIDS 994. The
  redlined schematic used to document configuration
  changes for the qual TPS CCA will be used for
  reworking the other TPS boards. The TPS CCA
  schematic diagram, assembly drawing and BOM/parts
  list will be revised to capture redline changes.
  GSFC inspection of reworked CCAs will be
  performed by Tracy Shepherd. Following rework,
  TPS CCAs will complete performance and thermal
  cycle testing and returned to General Technology
  for final assembly.
• Dispo 3 (Cullinan, 4/12/05) Rework (including
  capacitor/jumper wire staking with EA9394),
  inspection and Performance testing has been
  completed on TPS CCAs GT104, 105, 106, 108, 109,
  110. GT104, 105, 106 and 108 to be shipped to
  GT GT109, 110 still require performance and
  thermal cycle testing following rework.
  Photographs of individually staked
  capacitors/jumper wires and overall board views
  were taken for all boards and are stored on V
  drive under Ancillary file in Electronics folder
  (under GLAST folder on V drive).
• All remaining boards received from GT will be
  reworked per this NCR and AIDS 994.
• Dispo 4 (cullinan, 4/20/05) TPS boards GT109
  and GT110 successfully completed EICIT
  (LAT-TD-04850-1), SVT (LAT-TD-04849-1),
  performance testing (LAT-TD-01652-4), thermal
  cycling (5 cycles) and post thermal cycle
  performance testing (LAT-TD-01652-4) on AIDS 872
  following rework.
• All test results have been retained in the work
  order binders generated for each CCA and archived
  in bonded stores.
• The following drawings have been revised to
  document this TPS CCA rework and are currently in
  sign off cycle
• 1. TPS CCA assembly LAT-DS-02388, update to rev.
  58
• 2. TPS CCA Schematic, LAT-DS-02390, updated to
  rev. 57
• 3. TPS CCA BOM, LAT-DS-02391, updated to rev. 57
• Per MRB 4/14/05, DAQ Electronics group to provide
  an advisory memo to Systems Engineering
  documenting this anomaly and directing test and
  service operations of the TEM/TPS to avoid any
  condition that would risk initiating oscillation.

23
Reference

• NCR 562 (contd)
• MRB concluded that no additional EMI/EMC testing
  or workmanship vibration testing is required for
  the reworked qual TEM/TPS module.
• Plan is to close this NCR with MRB approval, and
  open new NCR to document required rework for TPS
  CCAs currently installed in TPS boxes of GLAT
  1752 and GLAT 1753 flight modules currently
  integrated onto Towers 1 and 2. Plan is to
  remove these TPS boxes and rework/replace with
  reworked TPS CCAs.
• (Cullinan, 7-14-05) NCR 562 created per MRB to
  direct disposition of GLAT 1752 and GLAT 1753
  TEM/TPS for reworking the TPS CCAs of these two
  assemblies.