INSTALLATION AND OPERATION LOAD SHARING MODULE Appendix B. - Guide for Handling and Protection of Electronic Controls, Printed Circuit Boards, & Modules Caterpillar

Appendix B. - Guide for Handling and Protection of Electronic Controls, Printed Circuit Boards, & Modules
1.1. Introduction
2.1. Preventing Electrostatic Damage
3.1. Reduce Static Generation
4.1. Dissipate Built-Up Charges
5.1. Handle Equipment Correctly
6.1. Protective Devices
7.1. Preventing Physical Damage
8.1. Preventing Electrical Damage
9.2. Installation
10.2. Testing and Servicing
11.2. Shipping
12.2. Storage


[Appendix B reproduces Woodward manual 82715.]

All electronic equipment contains components that can be damaged, or suffer reduced reliability, from improper handling or incorrect wiring. This manual describes methods of handling electronic equipment and techniques for connecting and checking system wiring. These methods and techniques, if used, will substantially reduce handling damage and in-service failures. Although some types of electronic equipment are more easily damaged by mishandling or incorrect wiring than other types, regular use of these methods and techniques will result in fewer damaged components and increased reliability for all types of electronic equipment.

Improper handling (installation, removal, storage, etc.) can cause two types of component failure: immediate failure or eventual failure (decreased reliability). Both of these types of failure, in turn, can be caused by electrostatic discharge, physical damage, or electrical damage.

An electrostatic discharge across a device which is sensitive to static electricity usually punctures an insulating layer, causing the device to fail immediately. However, an electrostatic discharge can also weaken an insulating layer without puncturing it, causing eventual premature failure with no immediate malfunction or sign of damage.

Rough handling or improper protection during installation, removal, shipping or storage can cause physical damage to a module, a printed circuit board (PCB), or a complete control. Again, the damage may not be apparent immediately, but may cause eventual premature failure.

Incorrect system wiring or improper test procedures can electrically damage a control or can cause temporary incorrect operation without actual damage.

In order to prevent these types of unnecessary damage to a control, module, or PCB, the following instructions must be followed.

Preventing Electrostatic Damage

To effectively reduce damage from electrostatic discharge, all four of the following precautions must be taken:

* Reduce the generation of static electricity
* Dissipate safely any charges that have built up
* Handle equipment correctly
* Use protective devices

The first of these four is the most important because, if no static electricity were generated, the other three precautions would not be necessary. However, since the generation of static electricity is impossible to completely eliminate, all four precautions must be taken to prevent damage from electrostatic discharge.

Reduce Static Generation

* Do not wear clothing that readily generates static electricity (synthetic materials generate large amounts of static electricity). Cotton or cotton-blend fabrics, for example, are good because they are not as likely to store electrostatic charges.
* Keep all plastic items away from any area where electronic devices are handled. Any plastic item is a potential static generator. This includes candy-wrappers, foam cups, synthetic carpet, foam cushions, etc.
* Avoid activities that produce static such as wiping feet or putting on smocks, when in the vicinity of static-sensitive devices.
* Maintain as high a humidity as is comfortable and practical.

Dissipate Built-Up Charges

* Always discharge any static charge your body might have built up before touching any electronic module, PCB, or control. To do this, touch and hold a grounded metal object for a minimum of two seconds.
* When connecting a cable to a control, discharge any charge the cable may have. Touch the cable connector to the receptacle before removing the protective cover from the receptacle. Then, remove the protective cover from the receptacle and connect the cable.

Handle Equipment Correctly

* Do not touch components, solder runs, or connectors on a PCB. Hold PCBs only by the edge and modules only by the handle (if provided) or by the front panel.
* When disconnecting a module from a cardcage-type control during testing or service, do not remove the module completely from the control. Pull it out only about 10-15 mm (about 1/2 inch) to disconnect it.

Protective Devices

* Controls are sent from the factory with protective covers on cable receptacles. Leave the cover on any receptacle that has no cable connected to it. Always install covers on all receptacles when a control is in storage.
* Install a Conductive PCB Shunt Bar on any PCB or module that is not installed in a control. Install PCB Shut Bars on all modules as soon as the module is removed from the control and keep the shunt bars on the modules during storage or shipment.
* When a module or PCB is removed from a control, insert it into an Antistatic Protective Bag.

Preventing Physical Damage

* Do not force a module when installing it into a control. If a module does not go into a control easily, check that the module is in the correct slot (each type of module is keyed to fit only into the correct slot), and that it is not upside down. Be sure that the module is being inserted straight, and that there are no bent pins or obstructions. Insert the module all the way in by hand before tightening the locking screws.
* Do not force a cable connector into its receptacle. Use only your hands, not pliers or other tools. If a connector doesn't easily go into its receptacle, check for bent pins or obstructions.

Preventing Electrical Damage


* When installing a control, double-check to be sure that all system wiring is correct. Do not connect the control until all wiring is correct.
* Do not use the control to check the system wiring; make sure that the wiring is correct before connecting it to the control.
* Do not make any connections with the power on. Doing so may damage the control and/or cause injury to personnel.

Testing and Servicing

* Do not make connections with power on.
* Double-check all test equipment connections before applying power.
* Use battery-operated test equipment whenever possible.
* Make sure that all test equipment is isolated from ground.
* Do not remove or install modules or PCBs with power on.


* Unless otherwise stated in a product manual, preparing a device for shipment should be as follows:
* When a module or PCB is shipped separately, use a conductive PCB Shunt Bar on it (if applicable) and put it into an Antistatic Protective Bag.
* Pack each module that is not installed in a control individually, each with a Conductive PCB Shunt Bar (if applicable) and each in its own Antistatic Protective Bag.
* Use a non-abrasive material to protect all surfaces of the unit.
* Pack a complete control, a module, or a PCB so that it has at least 100 mm (four inches) of tightly packed, industrial approved shock-absorbing material on all sides.
* Pack a complete control in a double-walled carton made of minimum 1500 N (340 pound) test material.
* Pack each module to be shipped in its own heavy cardboard box. Do not ship modules or PCBs in padded envelopes.


* Leave all controls, modules, and PCBs that are to be stored, in their shipping boxes, with all protective devices in place.
* Store electronic equipment in a cool, dry place.
* Long-term stored units may require operational power prior to installation and setup. Apply power to controls as described in the manual or unit wiring diagram. Modules either can be installed in an operating control, or in a special powered storage rack available from Woodward. This will ensure that the stored unit is functional.