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3.1 SAFETY INSTRUCTIONS
- Safety regulations demand that the set be restored to
its original condition and that components identical
wi t h the original types be used.
Safety components are marked by the symbol
A.
- ESD
~
~
Al l IC' s and many other semi-conductors are
susceptible to electrostatic discharges (ESD).
Careless handling during repair can reduce life
drastically.
When repairing, make sure that you are connected
with the same potential as the mass of the set via a
wrist wrap with resistance.
Keep components and tools also at this potential.
For detailed information see "Handling ESD-sensitive
components".
- A set to be repaired should always be connected to
the mains vi a a suitable isolating transformer.
- never replace any modules or any other parts while
the set i s switched on.
- Use plastic instead of metal alignment tools. This i n
order to prelude short-circuit or to prevent a specific
circuit form being rendered unstable.
3.2 SERVICING OF SMDs (Surface Mounted Devices)
3.2.1 General cautions on handling and storage
a. Oxidation on the SMDs terminals results i n poor
soldering. Do not handle SMDs with bare hand.
b. Avoid for storage places that are sensitive to
oxidation such as places with sulfur or chlorine gas,
direct sunlight, high temperatures or a high degree of
humidity.
As a result the capacitance or resistance value of the
SMDs may be affected.
c. Rough handling of circuit boards containing SMDs
may cause damage to the components as well as the
circuit boards. Circuit boards containing SMDs should
never be bent or flexed. Different circuit board
materials expand and contract at different rates when
heated or cooled and the components and/or solder
connections may be damaged due to the stress.
Never rub or scrape chip components as this may
cause the value of the component to change. Similary,
do not slide the circuit board across any surface.
3.2.2 Removal of SMDs
a. Heat the solder (for 2-3 seconds) at each terminal of
the chip. Small components can, by means of litz wire
and a limited horizontal force, be removed with the
soldering iron. They can also be removed with a
solder sucker (see Fig.
1
a) or
b. Whi l e holding the SMD with a pair of tweezers take i t
off gently using th soldering iron' s heat applied to
each terminal
(see
Fi g . 1 b).
c. Remove the excess solder on the solder lands by
means of litz wire or a solder sucker (see Fig. 1 c).
3.2.2.1 Caution on removal:
a. When handling the soldering iron, use suitable
pressure and be careful.
b. When removing the chip, do not use undue force with
the pair of tweezers.
c. The soldering iron to be used (approx. 30 W), must
preferably be provided with a thermal control
(soldering temperature about 225 to 250°C).
d The chip, once removed, must never be used again.
PCS 71 674
DISMOUNTING
VACUUM PISTON
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SOLDERING IRON
SOLDER WICK~ CLEANING
Fi g .
1
3.2.3 Attachment of SMDs
,1 761 All
C
a. Locate the SMD on the solder lands by means of
tweezers and solder the component at one side.
Ensure that the component i s positioned well on the
solder lands (see Fig. 2a).
b. Next complete te soldering of the terminals of the
component (see Fig. 2b).
MOUNTING
e
9
A
PAIR OF -wt:EZERS
a4?i
SOLDER
:J05-08mm
SOLDERING\.\ PRESSURE
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IFION
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EXAMPLES
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3
3.2.3.1 Caution on attachment:
a. When soldering the SMD terminals, do not touch them
directly with the soldering iron. The soldering must be
as quick as possible; care must be taken to avoid
damage to the terminals and the body itself.
b. Keep the SMD' s body i n contact with the printed
board when soldering.
c. The soldering iron to be used (approx. 30 W) must
preferably be provided with a thermal control
(soldering temperature about 225 to 250°C).
d. Soldering should not be done outside the solder land.
e. Soldering flux (of rosin) may be used but should not
be acidic.
f.
After soldering, let the SMD cool down gradually at
room temperature.
g. The quantity of solder must be proportional with the
size of the solder land. If the quantity is too great, th€
SMD might crack or the solder lands might be torn
loose from the printed board (see Fig. 3).
3.3 HANDLING ESD-SENSITIVE COMPONENTS
3.3.1 Personal safety
The testing, handling and replacing of ESD-sensitve
components requires special attention for personal
safety. A person dealing with ESD-sensitive
components should, normally speaking, be connected
vi a a resistance to the same potential as the chassis
of the set to protect him against direct contact with
the supply voltage.
Thi s resistance i s often applied i n the connection lead
of wrist wraps. If necessary, make use of an isolating
transformer.
3.3.2 Storage and transport
Transport and store the circuits and PCBs i n their
original packages.
As an alternative to the original package one may use
a conductive material or special IC package which
short-circuits al l the pins of the component with one
another.
Always discharge the package before opening it.
3.3.3 Testing or handling
Work on a conductive surface when testing loose
circuits and components or when transferring
components and circuits from one package to
another.
Use a conductive wrist wrap with lead to make an
electrical connection between the conductive surface
and yourself vi a a resistance i n the connection lead of
the wrist wrap.
Connect equipment and tools also with this conductive
surface.
Do not connect any signals to inputs as long as the
power supply of the set to be tested is off.
Al l the inputs that are not used should be connected
either to ground or to the supply voltage. When
testing, do not use any freon sprays for under-cooling
of sensitive components.
3.3.4 Mounting ESD-sensitive components
Mount ESD-sensitive components only after all other
components have been mounted.
Make sure that the components themselves, the metal
parts of the PCB, mounting equipment and mounting
operator are at the same potential level as the chassis
of the set.
If i t i s impossible to ground the PCB, the mounting
operator should pick the PCB up before bringing it
into contact with the components to be replaced.
Conducti v e sheet
Bi t
3.3.5 Soldering
Soldering iron tips, also those of low-voltage soldering
stations. should be kept at the same potential as the
components and the PCB.
It i s better to use solder-removing braid than solder
suckers.
3.3.6 Electrostatic charges
One should stick to the precautionary measures also
after the ESD-sensitive components have been
mounted on the PCB. Until the sub-PCBs have been
incorporated into a complete system on which the
correct supply voltages are connected, the PCB i s
nothing more than an extension of the conductors of
the components on this PCB. To prevent electrostatic
discharges from passing to the components vi a the
terminals, we recommend that you apply conductive
clips or conductive tape on the terminals of the PCB.
3.3.7 Transients (switch-on phenomena)
To prevent permanent damages as a result of
switch-on phenomena, no ESD-sensitive components,
or PCBs populated with these components, should be
inserted i n or removed from test-sockets or systems
with the supply voltage on.
Prevent switching peeks on the mains as a
consequence of switching electric equipment, relay
and DC lines on and off.
3.3.8 Working environment
The work bench for the service technician should look
like the one shown i n the figure.
3.3.9 Replacement of the Flat Pack IC's
For replacing a component see Fi g . 6 Dismounting
and Mounting. Also a number of precautions and
examples i s given.
When replacing a flat pack, rosin flux applied to the
device leads will ensure a good soldered joint.
Since rosin flux, when not properly heated by the
soldering process, i s sticky, it will attract dust which
will result i n component degeneration over a period of
time.
The removal of excess flux with a cleaner will not
solve this problem because the flux i s then even
spread over a greater area by the cleaner. Drying of
the flux can be accomplished by blowing the area with
a common hair dryer for
1
or
2
minutes at a distance
of approx. 10 centimeters.
Sol d eri n g i r on
Special attention should be paid i n regions having a
dry atmosphere and when the floor i s covered with a
nylon carpet or such.
Safety i s ol a ti n g transformer
Mi n
200
kil Pl u g/socket
Max.
1
Mil
WriSt
wrap
PHILIPS SAFETY GUIDELINES FOR THE PROFESSIONAL SERVICE TECHNICIAN
Important
Fire and Shock Hazard (Continued)
Proper service and repair Is Important to the safe, reliable operation 9.
of al l Phi l l p s equipment. The service procedures recommended by
Phi l i p s and described In this service manual are effective methods of
performing service operations. Some of these service operations
require the use of tools specially designed for the purpose. The
speclal tools shoul d be used when and as recommended.
After reassembly of the unit, al w ays perform an ac l e akage
test or resistance test from the l i n e cord to al l exposed metal
parts of the cabinet. Also, check al l metal control shafts (wi t h
knobs removed). antenna terminals, handles, screws, etc. to
be sure the unit i s safe to operate without danger of electrical
shock.
It Is Important to note that this manual contains various CAUTIONS
and NOTICES whi c h shoul d be carefully read i n order to mi n i m i z e the
*
Broken line:
-•-
•- •- •-
•
Leakage
Current Cold Check
ri s k of personal Injury to service personnel. The possibility exists
that Improper service methods may damage the equipment. It al s o 1
Is Important to understand that these CAUTIONS and NOTICES '
ARE NOT EXHAUSTIVE. Phi l l p s coul d not possi b l y know, evaluate
2 _
and advi s e the service trade of al l conceivable ways In whi c h service
3 .
might be done or of the possible hazardous consequences of each
way. Consequently, Phl l l p s has not undertaken any such broad
evaluation. Accordingly, a servicer who uses a service procedure or
tool whi c h Is not recommended by Phi l l p s must first .satisfy himself
thoroughly that neither hi s safety nor the safe operation of the
equipment wi l l be jeopardized by the service method selected.
Safety Checks
After the original service problem has been corrected, a complete
safety check shoul d be made. Be sure to check over the entire set.
not Just the areas where you have worked. Some previous servicer
may have left an unsafe condition, whi c h could be unknowi n gl y
passed on to your customer. Be sure to check al l of the following:
Fire and Shock Hazard
1. Be sure al l components are positioned i n such a way as to avoi d
Unpl u g the ac l i n e cord and connect a jumper between the two
prongs of the plug.
Turn on the power switch.
Measure the resistance val u e between the Jumpered ac pl u g
and al l exposed cabinet parts of the receiver, such as screw
heads, antennas, and control shafts. When the exposed
metallic part has a return path to the chassis, the readi n g
shoul d be between 1 megohm and 5.2 megohms. When the
exposed metal does not have a return path to the chassi s the
reading must be infinity. Remove the jumper from the a~ l i n e
cord.
TO
INSTRUMENTS
EXPOSED
METAL PARTS
0.15µF
WATER
PIPE
(EARTH
GROUND)
the possiblllty of adjacent component shorts. Thi s i s especially
Important on those units whi c h are transported to and from the
service shop.
Leakage
Current Hot Check
2. Never release a repaired unit unl e ss al l protective devices such 1 .
as Insulators, barriers, covers, strain reliefs, and other
hardware have been Installed according to the original design. 2.
Soldering and wi r i n g must be Inspected to locate possible cold
solder Joi n ts, solder splashes, sharp solder points, frayed
leads, pinched leads, or damaged Insulation (i n cl u di n g the ac 3.
cord
I,
Be certain to remove loose solder bal l s and al l other
Do not use an Isolation transformer for this test. Pl u g the
completely reassembled unit directly Into the ac outlet.
Connect a 1 . Sk, 1 OW resistor paralleled by a 0. 1 SuF. capacitor
between each exposed metallic cabinet part and a good earth
ground such as a water pipe, as shown above.
3.
4.
5.
6.
7.
8.
loose foreign particles.
4.
Check across-the-line components and other components for
physical evidence of damage or deterioration and replace If
necessary. Fol l o w original layout, l e ad length, and dress.
No lead or component shoul d touch a resistor rated at
1
watt or
more. Lead tension around protruding metal surfaces or edges
must be avoided.
5.
Use an ac voltmeter wi t h at least 5000 ohms/volt sensitivity to
measure the potential across the resistor.
The potential at
any
point shoul d not exceed O. 75 volts. A
l e akage current tester
may
be used to make thi s test: l e akage
current must not exceed 0.5 milliamps. If a measurement i s
outside of the specified limits, there Is a possibility of shock
hazard. The receiver shoul d be repaired and rechecked before
returning It to the customer.
Repeat the above procedure wi t h the ac pl u g reversed. (Note:
An ac adapter ts necessary when a polarized pl u g Is used. Do
not defeat the polarizing feature of the plug.)
Crltlcal components havi n g special safety characteristics are
Identified with a
A
by the Ref. No. In the parts 11st and enclosed
within a broken line• (where several crltlcal components are
grouped In one area) al o ng with the safety symbol
A
on the schematic diagrams and/or exploded vi e ws.
Parts Replacement
Replacement parts without the same safety characteristics
may create shock, fire, or other hazards.
When servicing any unit, al w ays use a separate Isolation
transformer for the chassis. Failure to use a separate Isolation
transformer may expose you to possible shock hazard, and
may cause damage to servicing Instruments.
Many electronic products use a polarized ac l i n e cord ( one wi d e
pi n ·on the plug). Defeating this safety feature may create a
potential hazard to the servicer and the user. Extension cords
whi c h do not Incorporate the polarizing feature shoul d never be
used.
LASER NOTE:
1 .
2.
Many electrical and mechanical parts In Phi l l p s equi p ment have
special safety related characteristics. These characteristics
are often not evident from vtsual inspection nor can the
protection afforded by them necessarily be obtained by usi n g
replacement components rated for hi g her voltage, wattage,
etc. The use of a substitute part whi c h does not have the same
safety characteristics as the Phi l i p s recommended
replacement part shown In this service manual may create
shock, fire, or other hazards. Under no circumstances shoul d
the orl g tnal desi g n be modified or altered without written
per1:1l s sl o n from Phi l l p s. Phi l l p s assumes no llablllty. express or
Implied, arising out of any unauthorized modification of desi g n.
Servicer assumes al l liability.
Al l l C s and many other semiconductor parts are susceptlble to
electrostatic discharges (ESD). Careless handl i n g duri n g
repair can reduce the life of the part drastically.
DANGER - lnvlslble laser radiation when open. AVOID DIRECT EXPOSURE TO BEAM.
CAUTION - Use of controls or adjustments or performance of procedures other than those specified herei n may result In hazardous
radiation exposure.
CAUTION - The use of optical Instruments wi t h this product wi l l Increase eye hazard.
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