global Laptop and motherboard repair tutorial | Page 83

will fail but rarely will…BIOS chipsets will fail too, they will get blow outs in the center area of the
chips surface and is usually visible.
IMPORTANT Addition
A lot of motherboard failures are not a direct result of ―mother Natureǁ or the mis-use or even
thermal or mechanical breakdown. There are other Not Well Known ways a motherboard component
can fail. Packaging and Storage is one. The moisture content and chemical exposure in the packing
materials can greatly affect the longevity and stability of the Motherboard and Components thereof.
This can cause ―motherboard Warpǁ, it can also deteriorate certain affected components on the
board, even damaging the contacts. It will deteriorate the wires and cables making them brittle and
fragile, it can cause a lot of harm.
Another hidden cause left undiagnosed can be an incorrectly covered trace or land (manufacturer
defect). This can cause shorts, it can cause trail blow-outs because the heat generated from the PCBs
components will further wear away at the fault areas, causing that component to fail, which for
example can throw dc voltage through a path requiring no dc.
Another hidden cause left undiagnosed is a solder chip or ball that was left on the board after the
manufacturer completed build on the board. This piece might have stuck to an area on the board
having a ―negativeǁ contact, then at some point that chip or ball was knocked loose being knocked
around inside the laptop until eventually touching a voltage regulator positive pin arm or similar
components power contact. Which; in turn, would blow that; or any related component, leaving no
suspect to the cause of the failure upon inspection.
THE POWER CHOKE COIL, Power Inductors & Chokes
A choke is a coil of insulated wire, often wound on a magnetic core, used as a passive inductor
which blocks higher-frequency alternating current (ac) in an electrical circuit while passing signals of
much lower frequency and direct current by having an impedance largely determined by reactance,
which is proportional to frequency (see Inductor and Inductance). Chokes are typically used as the
inductive components in electronic filters.
The name comes from blocking—"choking"—high frequencies while passing low frequencies. It
is a functional name; the same inductor is often called a "choke" if used to block higher frequencies,
but a "coil" or "inductor" if, say, part of a tuned circuit.
SMD shielding power inductor
1.Size:8.3x8.3x4.0
2.Inductance:1.8-100uH
3.Current:1.05-7A
Power Chip Inductor
Characteristics:
* Compact multilayer type
* Suitable for applications with high currents up to 2.5 A * DCR values below 0.2 Ω
* Magnetically shielded construction: No crosstalk
* Operating temperature: – 40 °C to 125 °C
* Recommended soldering profile: Reflow
* Available in two different types
Applications: