Leach Backplate and Connector MountCritical Design Review

Iain Marcuson12/03/2013

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Instructions: Goals

1. The goal of the CDR is to ensure that the design is ready for fabrication, assembly, and validation.

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Instructions: Required Elements

1. Goal of Review2. Goal of system3. Requirements 4. Constraints5. Functional block diagram6. System block diagram7. Analysis showing that system satisfies requirements8. Parts list, with costs and availability9. Sequence of tasks10. Schedule of tasks with identified resources11. Budget12. Risks and mitigations13. Monitoring plan

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Instructions: Review Success Criteria

1. There is an explicit demonstration that each requirement is satisfied by the design.

2. >80% of drawings are ready to be submitted for fabrication.

3. All quotes have been obtained, including costs and lead times.

4. The proposed budget is less than the available budget.5. The final need date has been identified from an

existing project schedule.6. The system will be delivered by the need date.7. Lead times are compatible with the schedule.

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Goal of Review

1. The goal of this review is to validate the drawings for the back plate and new mounting scheme of the new Leach assembly.

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Goal of System

1. Connect internal clock and video boards to external connectors.

2. Maintain compatibility with current external connectors.

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Requirements

1. The new back panel must be compatible with the current external Leach connectors.

2. It must be possible to connect the internal connectors to the back panel from the outside, with little internal manipulation.

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Constraints

1. The backplate must be of a thickness that only requires cutouts and counter-boring.

2. The backplate must accommodate available solder-cup connectors.

3. The design must not put stress on the board connectors.

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Functional Block Diagram

Card

Connector x9

BackplateExternal Cable to Dewar

Card x5

There are five cards. Four cards have two connectors and one card has a single connector. The connectors are rear-mounted to the backplate, with an aperture for each connector.

System Diagram

Dewar

Leach

Power Supply

Computer

Leach Backplate

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Detailed Designs

Air Intake Outer

Dimensions Air Intake

DB-37

DB-25

DB-15

0.5"

0.75

"

0.5" 1.563"

1

.563

"

.359

2.211"

2.747"

0.506"

.355

2.101"1.555"

1.56"1.02"

2.5"

1.852"1.312"

0.281"

1.25"

Black circles are 0.125" and drilled through. Hollow circles are 0.237" counter-bored to a depth of 1/16". Back panel is 1/8" thick.

There is a vertical spacing of 0.02" between DB-25 and DB-15 connectors

2.375"

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Drawings

Air Intake Outer

Dimensions Air Intake

DB-37

DB-25

DB-15

0.5"

0.75

"

0.5" 1.563"

1

.563

"

.359

2.211"

2.747"

0.506"

.355

2.101"1.555"

1.56"1.02"

2.5"

1.852"1.312"

0.281"

1.25"

Black circles are 0.125" and drilled through. Hollow circles are 0.237" counter-bored to a depth of 1/16". Back panel is 1/8" thick.

There is a vertical spacing of 0.02" between DB-25 and DB-15 connectors

2.375"

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Drawings

Video BoardMale DB25Digikey5125MEA-ND

Male DB15Digikey5115MEA-ND

Cable manufactured

by Arc

DB

50

JackscrewGlenair 289-016-D or equivalent

Back Plate

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Drawings

ARC32 BoardMale DB37Digikey 1237MA-ND

Cable manufactured

by Arc

DB

37

JackscrewGlenair 289-016-D or equivalent

Back Plate

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Drawings

Female 50 Pin Male DB-15 Male DB-25 Function

1 14 Input -A

2

3 3 Input -B

4 17 Input -C

5

6 6 Input -D

7 20 Input -E8

9 9 Input -F

10 23 Input -G

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12 12 Input -H

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14 7 Bias out 7

15 5 Bias out 5

16 3 Bias out 3

17 1 Bias out 1

18 1 Input +A

19 15 Input +B

20

21 4 Input +C

22 18 Input +D

23

24 7 Input +E

25 21 Input +F

26

27 10 Input +G

28 24 Input +H

29

30

31 6 Bias out 6

32 4 Bias out 4

33 2 Bias out 2

34 2 Ground

35 5 Ground

36 8 Ground

37 11 Ground

38 13 Ground

39 16 Ground

40 19 Ground

41 22 Ground42 25 Ground

43 11 Ground

44 10 Ground

45 9 Ground

46 8 Ground

47 12 +16.5 V

48 13 -16.5 V

49 14 +6.5 V

50 15 -6.5 V

Arc 32 DB37 Pin Back Panel DB37 Pin Function1 1 CLK02 2 CLK13 3 CLK24 4 CLK35 5 CLK46 6 CLK5

7 7 CLK68 8 CLK79 9 CLK8

10 10 CLK911 11 CLK1012 12 CLK1113 13 CLK1214 14 CLK1315 15 CLK1416 16 CLK1517 17 CLK1618 18 CLK1719 19 CLK1820 20 +15V21 21 -15V22 22 GND23 23 GND24 24 GND25 25 GND26 26 GND27 27 GND28 28 GND29 29 GND30 30 GND31 31 GND32 32 GND33 33 CLK1934 34 CLK2035 35 CLK2136 36 CLK2237 37 CLK23

Green lines from pinout chart. Yellow lines from other experiments. All others assumed.

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Analysis/Results

0.0625"

0.168"

Chassis

Jackscrew

0.1055"

We have 0.1055" to grab the jackscrew with the driver.

We must be able to drive the jackscrew externally, ideally without needing a large counterbored hole to provide room for the driver. The below diagram shows that we have enough length of jackscrew to drive.

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Analysis/Results

0.125"

0.0625"

0.168"

0.2305"

Rear P

ane l Connec tor

External Connector

0.234375"

Jackscrew

The Rear Panel Connector envelopes the external connector, but is shown behind it for clarity.

Rear Panel Mounting Scheme and Fit Check

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Parts List, Costs, and Lead Times

Part Number

Part Description

Vendor Cost Each

Quantity Needed

Quantity Available

Total Cost

5115MEA-ND

Male DB-15 Digi-Key

3.37 4 511 13.48

5125MEA-ND

Male DB-25 Digi-Key

3.79 4 305 15.16

1237ME-ND

Male DB-37 Digi-Key

2.85 1 458 2.85

289-016-D Low Profile Jackposts

Glenair 34.57 9 >=25 311.13

MD50F20000

Female DB-50

Arc 4

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Risks

1. Panel connectors could be inline with board connectors, leading to undesired stresses and broken connections.

2. Jackscrews may not hold in place due to lack of lockwasher.

3. Bob Leach may discover the price of the jackscrews to be excessively high.

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Mitigation

1. Connectors in linea. We can collaborate with Leach to ensure that

cutouts are such that connectors are not in line.b. It may be the in line connectors are not a problem.c. Extra wire could be added to the internal cables to

prevent stress transfer.

2. Jackscrews looseninga. Threading tape may be used to increase adhesion

and provide expedient removal.b. Thread-locking compound may be used to ensure

adhesion at the cost of ease of removal.

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Mitigation (continued)

3. High Cost of Jackscrewa. We can provide additional funds for the jackscrews.b. We have successfully machined such jackscrews

ourselves in the past, and could supply the jackscrews separately.

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Schedule

1. Design will be submitted to Bob Leach. It is presumed that the back panel will be ready by the end of the Leach system fabrication time.

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Sequence of Tasks

1. Fabrications will be performed by Mr. Leach. He will conduct fabrication along with the Leach system.

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Budget

1. This project is included in the budget for Leach.

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Monitoring/Verification Plan

1. A one-to-one drawing has been made to test fit components.

2. If all nine connectors can fit into the back plate and be attached, the mechanical design will be verified.

3. If successful Leach gain experiments can be conducted, we have evidence of preliminary correct cable construction and operation.

4. Dark current data, compared with similar experiments from the previous Leach system, will provide confirmation of cable correctness.