Safety Pre­cau­tions before per­form­ing any instal­la­tion, dis­as­sem­bly or reassembly

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Observe the fol­low­ing safety pre­cau­tions before per­form­ing any instal­la­tion or break/fix pro­ce­dures involv­ing dis­as­sem­bly or reassembly:

•Turn off the sys­tem and any attached periph­er­als.
•Dis­con­nect the sys­tem and any attached periph­er­als from AC power, and then remove the bat­tery.
•Dis­con­nect any tele­phone or telecom­mu­ni­ca­tions lines from the sys­tem.
•Use a wrist ground­ing strap and mat when work­ing inside any com­puter sys­tem to avoid elec­tro­sta­tic dis­charge (ESD) dam­age.
•After remov­ing any sys­tem com­po­nent, care­fully place the removed com­po­nent on an anti-static mat.
•Wear shoes with non-conductive rub­ber soles to help reduce the chance of being shocked or seri­ously injured in an elec­tri­cal accident.

Standby Power
Prod­ucts with standby power must be com­pletely unplugged before open­ing the case. Sys­tems that incor­po­rate standby power are essen­tially pow­ered while turned off. The inter­nal power enables the sys­tem to be remotely turned on (wake on LAN), sus­pended into a sleep mode, and have other advanced power man­age­ment fea­tures. After unplug­ging the sys­tem, allow the charge to drain from the cir­cuits by wait­ing approx­i­mately 30 to 45 sec­onds before remov­ing components.

Electro-Static Dis­charge (ESD) Pro­tec­tion
ESD is a major con­cern when han­dling elec­tronic com­po­nents, espe­cially sen­si­tive devices such as expan­sion cards, proces­sors, mem­ory DIMMs, and sys­tem boards. Very slight charges can dam­age cir­cuits in ways that may not be obvi­ous, such as inter­mit­tent prob­lems or a short­ened prod­uct lifes­pan. As the indus­try pushes for lower power require­ments and increased den­sity, ESD pro­tec­tion is an increas­ing concern.

Due to the increased den­sity of semi­con­duc­tors used in recent elec­tronic prod­ucts the sen­si­tiv­ity to sta­tic dam­age is now higher than in pre­vi­ous prod­ucts, for this rea­son some pre­vi­ously approved meth­ods of han­dling parts are no longer applicable.

WARNING:
Do not use an ESD ground­ing strap when work­ing on the inter­nal parts of a mon­i­tor, like the CRT, because the stored volt­age is extremely harmful.

There are two rec­og­nized types of ESD dam­age, “cat­a­strophic” and “Inter­mit­tent” fail­ures.

Cat­a­strophic - The dam­age causes an imme­di­ate and com­plete loss of device func­tion­al­ity. An exam­ple of cat­a­strophic fail­ure is a mem­ory DIM which has received a sta­tic shock and imme­di­ately gen­er­ates a “No POST/No Video” symp­tom with a beep code emit­ted for a miss­ing or non-functional memory.

NOTE:
Cat­a­strophic fail­ures only rep­re­sent roughly 20% of ESD related failures.

Inter­mit­tent - The DIMM receives a sta­tic shock, but the trac­ing is merely weak­ened and does not imme­di­ately pro­duce out­ward symp­toms related to the dam­age. The weak­ened trace might take weeks or months to melt, and in the mean­time may cause degra­da­tion of mem­ory integrity, inter­mit­tent mem­ory errors, etc.

NOTE:
Inter­mit­tent fail­ures rep­re­sent almost 80% of ESD related fail­ures. This means that the major­ity of the time when the dam­age occurs, it is not imme­di­ately recognizable.

Of these two types, the more dif­fi­cult to rec­og­nize and trou­bleshoot is the “Inter­mit­tent” (also called Latent or “walk­ing wounded”) fail­ure. The image below is an exam­ple of an “Inter­mit­tent” dam­age to a mem­ory DIMM trace. As you can see, the dam­age is done although the symp­toms may not become an issue or cause per­ma­nent fail­ure symp­toms for some time after the dam­age occurs.

Inter­mit­tent (Latent) dam­age to a wiring trace

To pre­vent sta­tic dam­age, do the following:

•Use a Wired (not wire­less) ESD wrist strap that is prop­erly grounded. The use of wire­less anti-static straps in no longer allowed, as they do not give ade­quate protection.

Wired ESD Strap (Acceptable)

Wire­less ESD Strap (Unacceptable)

•Fur­ther­more, sim­ply touch­ing the chas­sis before han­dling parts is no longer allowed because this method does not ensure ade­quate ESD pro­tec­tion on parts with increased sen­si­tiv­ity to ESD damage.

Chas­sis “Bare metal” Ground­ing (Unacceptable)

•Han­dle all static-sensitive com­po­nents in a static-safe area. If pos­si­ble, use anti-static floor pads and work­bench pads.
•When han­dling static-sensitive com­po­nents, grab them by the sides, not the top. Avoid touch­ing pins and cir­cuit boards.
•When unpack­ing a static-sensitive com­po­nent from its ship­ping car­ton, do not remove the com­po­nent from the anti-static pack­ing mate­r­ial until you are ready to install the com­po­nent. Before unwrap­ping the anti-static pack­ag­ing, be sure to dis­charge sta­tic elec­tric­ity from your body.
•Before trans­port­ing a static-sensitive com­po­nent, place it in an anti-static con­tainer or packaging.

Insu­la­tor Ele­ments
It is crit­i­cal to keep ESD sen­si­tive devices away from inter­nal parts which are insu­la­tors and are often highly charged. These are ele­ments such as plas­tic heat sink casings.

DIMM lying on an insu­la­tor part (plas­tic heat sink shroud) – Unacceptable

DIMM kept sep­a­rate from the insu­la­tor part – Acceptable

Trans­port­ing Sen­si­tive Com­po­nents
When trans­port­ing ESD sen­si­tive com­po­nents, it is crit­i­cal to place these parts in anti-static bags for safe transport.

ESD Pro­tec­tion Sum­mary
It is strongly sug­gested that all field ser­vice engi­neers use the tra­di­tional “wired” ESD ground­ing wrist strap and pro­tec­tive anti-static mat at all times when ser­vic­ing prod­ucts. In addi­tion, it is crit­i­cal that the engi­neer keep sen­si­tive parts sep­a­rate from all “insu­la­tor” parts while per­form­ing ser­vice and use anti-static bags for trans­port of sen­si­tive components.

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