NEI 11ak10 free download

File name 11ak10.txt

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