Barrel Harness Status

1
Barrel Harness Status

• Problems with DORIC4A.
• Tolerances and fibre layout.
• Harness status in Taiwan.
• Harness testing at RAL.

2
DORIC4A problems

• DORIC4As tested on wafer and only good die were
  given to Taiwan.
• Yield of DORIC4As when mounted on doglegs was
  50. ESD precautions were used at Radiantech
  butclear evidence of ESD damage seen (? photos).

3
DORIC4A Solutions

• Process changed to avoid sharp pointers and use
  automatic die bonding.
• 122 DORIC4As now mounted on doglegs and all
  tested to work.
• Dont want to use DORIC4As mounted on doglegs
  before procedure was changed because of worries
  about long term reliability.
• Difficult to re-work doglegs because of cover.

4
Harness Lengths

• Better definition of tolerances and which lengths
  are the critical ones to measure.
• i/f PCB to PPB1 -0 20 mm
• i/f PCB to MT connectors -0 20 mm
• Position of MT splice /- 10mm or up to -50mm if
  splice needs to be redone.
• Detailed harness engineering drawings showing
  fibre layout and check lengths (? figure).

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7
Fibre Layout

• Jigs produced in order to ensure correct fibre
  loops for fibres leaving doglegs before harness
  clip.
• Photo shows prototype jig.

8
Schedule

• Batch process so many steps well advanced
• Opto-packages for 55 harnesses.
• Doglegs assembled for 23 harnesses.
• 4 Harness completed May 5th
• 20 Harness completed May 13th
• 36 Harness completed May 15th
• 64 Harnesses (all B3) by May 31st
• Complete all barrel harnesses by August 25th.
• See schedule on web
• http//www-pnp.physics.ox.ac.uk/weidberg/producti
  on/Barrel_Harness_Schedule.xls

9
Harness Testing at RAL

• Complete system for bench testing barrel
  harnesses is working at RAL and was used to test
  the first two barrel harnesses. Software ok.
• Current system requires temporary cables to be
  connected to PPB1.
• Upgrade test system to use TPPs and TIs. The TPPs
  and TIs would then stay with the harness during
  subsequent assembly of harness to barrel.
• Minimise number of connections made to PPB1.
• TIs and TPPs should be available in 1 week.
• System for testing harness on barrels still being
  developed.
• Loop back PCBs (send TTC ? data links)
• Simple cheap BER test system being made by
  Minglee (end May).
• Allows for BER testing of 4 harnesses in parallel
  (could be done overnight).
• Testing Harnesses on receipt of barrels at
  Oxford.
• Simple loop back PCB tested and works.
• Requires ROD software to use this (Peter
  Phillips).