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11AK10 /VESTEL 5559/5419 CHASSIS SERVICE NOTES
#G This Chassis is fairly conventional with no nasty suprises.
It is software controlled via an I2C bus system,modular
construction making servicing easy if extension cards are used,
difficult if not. A switch mode power supply isolates the Mains
input from the user electronics.
#1 AUDIO STAGES
NO AUDIO OUTPUT
Check supply lines to all devices +28V to IC309 and +12V to
others. Check with scope signal path. If audio into IC308 and
not coming out, check the I2C bus. It is possible that an I2C bus
contention not connected with IC308 has happened and the fault
could be else where.
NO AUDIO OUTPUT IC309 DESTROYED OR GETTING HOT.
Check for oscillation on the output pins, if both channels are
oscillating check C373, if one channel is oscillating check Zobel
components on faulty channel ie C361 & R338/ C360 & R339.
LOW LEVEL MONO SOUND (Nicam ok).
Check alignment if YL302.
ONE CHANNEL MISSING (Probably Nicam).
Check signal paths with scope.
#2 COLOUR DECODER (CHROMA PATH).
NO CHROMA. (OSD & TEXT OK).
#3 CRT BASE
#4 HORIZONTAL OUTPUT
#5 I.F JUNGLE
This circuit has become totally integrated with various other
sections inside IC401 (TDA8962A).
#6 KEYPAD/IR MODULE
#7 LUMA PATH
IC401 (TDA8962A)
NO LUMA OR INTERMITTENT.
Check pin 21 it should be at 0V, if it is around +2V check that
pin 19 of IC101 (Text IC) is pulled down, if not check X101
(27Mhz).
#8 MICROCONTROLLER
#9 NICAM MODULE
#10 POWER SUPPLY.
This psu is a conventional switched mode type using a
#11 TELETEXT
There are two versions of the Text models, one Fast Text using
an additional Personality module and the other Single page Text,
without the personality module and extra memory IC102.
NO TEXT (Also normal video may intermittently blank, and sound
mute).
X102 (27Mhz) crystal faulty.
#12 TUNER & BANDSWITCH
#13 SCART SOCKET
#14 VERTICAL OUTPUT