VESTEL AK33 TECHNICAL CHANGE BULLETIN change111

: 111

ELEKTRONİK A.Ş.

TECHNICAL CHANGE BULLETIN

CHANGE NO
REF NO :
DATE :15.03.2002

AFFECTED MODELS: ALL MODELS WITH 11AK33 CHASSIS

START DATE : 22.03.2002
REASONS OF CHANGE:

Subject : Sound from speaker in stand-by from TV Sets with AK33 chassis .

Problem : When TV is switched in stand-by always sound is coming from the speaker .

Reason : Because of tolerances from SMPS Transformer the Audio supply Voltages are slightly different and in

this case the Audio Amplifier is unbalanced and produce a sound , which is hereble from the speaker .

Solution : The Audio Amplifier is going to be muted during stand-by mode . With the following modification

Transistor Q715 is switched on during stand-by , voltage of mute pin of Audio Amplifier is higher than
supply voltage , in that case Audio Amplifier is going to switch off .

+5V / st-by

BA159Res 1k

R721

C866

R724

D703

+14V-A

OUT

NO PCB

VESTEL CODE COMPONENT NAME POSITION NUMBER QUANTITY

CODE

1

2

IN

NO PCB

VESTEL CODE COMPONENT NAME POSITION NUMBER QUANTITY

CODE
1
2
3

30012657 RES SMD 1/16W 1K J (0603) NOT1 1

30001318 DIODE BA159 1A/800V 20A NOT2 1

30011744 CABLE 0.6MM (8 CM) NOT3 1

4
5

Q715

Mute / Pin 5 of Audio Amplifier

R748

CUSTOMER SUPPORT

ENGINEER

S.DEMIRKAYA

Form Rev.No:00 Form No: 10.KALT.68

QUALITY

MANAGER

ALI TUNC CAN

Katod of D703

Cable between Katod of BA159
and Katod of D703 ( note 3 )

Smd 1k
(note 1 )

Diode BA159
(note 2 )