Philips 32PHS5505/12, Руководство по обслуживанию

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2. Precautions, Notes, and
Abbreviation List
2.1 Safety Instructions
Safety regulations require the following during a repair:
•
Connect the set to the Mains/AC Power via an isolation
transformer (> 800 VA).
•
Replace safety components, indicated by the symbol
△
!
, only by components identical to the original ones.
Any other component substitution (other than original
type) may increase risk of fire or electrical shock hazard.
Safety regulations require that after a repair, the set must
be returned in its original condition. Pay in particular
attention to the following points:
•
Route the wire trees correctly and fix them with the
mounted cable clamps.
•
Check the insulation of the Mains/AC Power lead for
external damage.
•
Check the strain relief of the Mains/AC Power cord for
proper function.
•
Check the electrical DC resistance between the
Mains/AC Power plug and the secondary side (only for
sets that have a Mains/AC Power isolated power
supply):
1. Unplug the Mains/AC Power cord and connect a wire
between the two pins of the Mains/AC Power plug.
2. Set the Mains/AC Power switch to the “on” position
(keep the Mains/AC Power cord unplugged!).
3. Measure the resistance value between the pins of the
Mains/AC Power plug and the metal shielding of the
tuner or the aerial connection on the set. The reading
should be between 4.5 MΩ and 12 MΩ.
4. Switch “off” the set, and remove the wire between the
two pins of the Mains/AC Power plug.
•
Check the cabinet for defects, to prevent touching of any
inner parts by the customer.
2.2 Warnings
•
All ICs and many other semiconductors are susceptible
to electrostatic discharges (ESD
). Careless handling
during repair can reduce life drastically. Make sure that,
during repair, you are connected with the same potential
as the mass of the set by a wristband with resistance.
Keep components and tools also at this same potential.
•
Be careful during measurements in the high voltage
section.
•
Never replace modules or other components while the
unit is switched “on”.
•
When you align the set, use plastic rather than metal
tools. This will prevent any short circuits and the danger
of a circuit becoming unstable.
2.3 Notes
2.3.1 General
• Measure the voltages and waveforms with regard to the
chassis (= tuner) ground ( ), or hot ground ( ),
depending on the tested area of circuitry. The voltages
and waveforms shown in the diagrams are indicative.
Measure them in the Service Default Mode with a colour
bar signal and stereo sound (L: 3 kHz, R: 1 kHz unless
stated otherwise) and picture carrier at 475.25 MHz for
PAL, or 61.25 MHz for NTSC (channel 3).
•
Where necessary, measure the waveforms and voltages
with ( ) and without ( ) aerial signal. Measure the
voltages in the power supply section both in normal
operation ( ) and in stand-by ( ). These values are
indicated by means of the appropriate symbols.
2.3.2 Schematic Notes
•
All resistor values are in ohms, and the value multiplier
is often used to indicate the decimal point location (e.g.
2K2 indicates 2.2 kΩ).
•
Resistor values with no multiplier may be indicated with
either an “E” or an “R” (e.g. 220E or 220R indicates 220
Ω).
• All capacitor values are given in micro-farads (
µ
= x10 -6 ),
nano-farads (n = x10 -9 ), or pico-farads (p = x10 -12 ).
• Capacitor values may also use the value multiplier as
the decimal point indication (e.g. 2p2 indicates 2.2 pF).
•
An “asterisk” (*) indicates component usage varies.
Refer to the diversity tables for the correct values.
•
The correct component values are listed on the Philips
Spare Parts Web Portal.
2.3.3 Spare parts
For the latest spare part overview, consult your Philips
Spare Part web portal.
2.3.4 BGA (Ball Grid Array) ICs
Introduction
For more information on how to handle BGA devices, visit
this URL:
http://www.atyourservice-magazine.com. Select
“Magazine”, then go to “Repair downloads”. Here you will
find Information on how to deal with BGA-ICs.
BGA Temperature Profiles
For BGA-ICs, you must use the correct temperature-
!