20-40-11
ALL ú ú 01 Page 204 ú Nov 15/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 737-300/400/500MAINTENANCE MANUAL
WHEEL WELL TORQUE BOX VERTICAL SUPPORT
SEE A
VERTICAL SUPPORT
GROUNDING STUD
MAIN GEAR WHEEL WELL GROUNDING STUD LOCATION A Static Grounding Point Location Figure 201
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20-40-11
ALL ú ú 01 Page 205 ú Nov 15/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
ELECTROSTATIC DISCHARGE SENSITIVE DEVICES - MAINTENANCE PRACTICES
_________________________________________________________________
1. General (Fig. 201)_______
A. This procedure contains these tasks:
(1)
ESDS Printed Circuit Boards Removal
(2)
ESDS Printed Circuit Boards Installation
(3)
ESDS Metal Encased Units Removal
(4)
ESDS Metal Encased Units Installation
B. Many electronic line replaceable units (referred to as LRUs) contain micro-circuits and other sensitive devices which can be damaged internally by electrostatic discharges. These LRUs are identified as Electrostatic Discharge Sensitive (referred to as ESDS). The placards installed on the ESDS LRUs show that you must be careful. The persons who remove, install, and move the ESDS LRUs must know about static electricity and the protection from static discharges that is necessary.
C. Electrostatic charges can be caused by these: human bodies, hair, clothing, floors, equipment racks, and equipment units. An electrostatic discharge is electrostatic energy transmitted between materials of different electrical potentials. Electrostatic discharges from nylon clothing or human hair onto polyethylene or steel can cause damage to ESDS components. Damage to the internal components of an ESDS LRU can cause failure with one static discharge. System properties can change with time because of many static discharges.
D. The function of these procedures is to show the maintenance persons how to know and touch the ESDS LRUs. These procedures contain the precautions that are necessary to safely touch the units that are identified by the ESDS placard. Three types of decals are in used to identify the units with ESDS sensitive circuits. The military and commercial symbols are used on some units, while the international (JEDEC) symbol is used on most ESDS placards (Fig. 201). The ESDS printed circuit boards that are LRU's are identified with a "STATIC SENSITIVE" placard (Fig. 201).
TASK 20-40-12-002-001
2. ESDS Printed Circuit Boards Removal___________________________________
A. Equipment
(1) Conductive Bags - 3M type 2100
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20-40-12
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 737-300/400/500MAINTENANCE MANUAL
STATIC SENSITIVE
TYPICAL BOEING ESDS DECALS
Static Discharge Sensitive Devices Identifiers
Figure 201
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20-40-12
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
(2)
Conductive Plastic Carrier - Electrical Insulation Suppliers PCC-700
(3)
Ohmeter
(4)
Wrist Straps - 3M 2066 or 2067
(5)
100% Cotton Twine - Commercially Available
(6)
ESDS Labels
(a)
JEDEC International Label - multi-source
(b)
3M - No. 7102
B. Remove the Printed Circuit Boards with the STATIC SENSITIVE placards
NOTE: The placards on the outer area of the card files show the cards
____ that contain the ESDS printed circuit boards that are LRU's.
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