Sony DTV-01, Manual

Page: 64 / 132

67
Overall Protection Block
Protection
The protection circuitry on the G and D boards monitor the following
items and shuts the TV off if there is a problem:
G Board:
=
Vertical deflection loss (self diagnostics - light indication)
=
+5V OCP monitored (self diagnostics - light indication)
=
+5V OVP monitored (self diagnostics - light indication)
= +135V OCP monitored (self diagnostics - light indication)
=
+135V OVP monitored (self diagnostics - light indication)
=
+15V OVP
= Surge relay RY5502 not energized.
D Board:
=
Driver supply voltage OVP
=
H. Output OVP
=
H. Output OCP
= FBT Output OVP
=
H Centering IC4003 OCP
Four general failure detectors on the G board not only shut down the
TV set but also inform the Main Micro IC3251 of the failure. The Main
Micro IC3251 provides a blinking light indication of the failure. This
micro routine is called the self-diagnostic program and found in many
Sony Trinitron TV sets made since late 1997.
Self Diagnostics
This TV also has self-diagnostics circuitry that is connected to five
sensing circuits. A failure detected by one of these circuits is regis-
tered by the Main Micro IC3251 and permits it to blink the front panel
standby light a number of times to identify the problem area.
S ta n d b y L ig h t In d ic a t io n
# tim e s
lig h t
b lin k s
S h u td o w n c a u s e /
S y m p to m
P o s s ib le d e f e c tiv e c ir c u it
2 B + O C P / T V S h u t d o w n H o r iz o n t a l d r iv e r , h o r iz o n ta l
o u t p u t, F B T , o r P W M .
D y n a m ic fo c u s c ir c u it &
P in c u s h io n c o r r e c t io n c ir c u it.
3 B + O V P / T V S h u t d o w n C o n v e r t e r 1 :
•
r e g u la t io n fa ilu r e
•
o s c illa t o r o ff f r e q u e n c y
4 S e r ia l D a ta s h u t d o w n
in s tr u c tio n fr o m D e f le c tio n
C o n tr o l IC 1 3 0 5 to M a in
M ic r o I C 3 2 5 1 .
/ T V S h u td o w n
V e r t ic a l fa ilu r e
H o r iz o n t a l s c a n ( F B T ) d e r iv e d
v o lta g e fa ilu r e ( n o H o r iz o n ta l)
L o w c o n v e rt e r 1 o r 2 v o lt a g e s
( c a u s in g lo w s c a n v o lt a g e s )
5 S ta n d b y lig h t b lin k s 5
t im e s a n d r e p e a ts .
W h it e s in t h e p ix a r e n o t
w h it e . S o u n d O K / V id e o
P r o c e s s o r IC 3 0 0 5 c a n ’t
W h it e b a la n c e ( IK fa ilu r e ) .
T h is f a ilu r e w ill n o t s h u t
d o w n t h e T V s e t.
S c r e e n c o n t r o l s e tt in g to o lo w .
V id e o p r o c e s s o r o r v id e o
o u t p u t s ta g e fa ilu r e . S e e v id e o
p r o c e s s .
I n c o rr e c t C r o r C b d a t a in th e
s e r v ic e m o d e .
6 + 5 V O V P , O C P /
T V S h u t d o w n
C o n v e r t e r 2 r e g u la tio n .
S h o r t o n + 5 V lin e .
Further details about the self-diagnostics circuitry and its OSD for inter-
mittent problems are explained in the service manual.
Repair Strategy
The strategy for identifying the cause of the TV shutdown is the same as it
would be for a projection TV or even a camcorder:
1. Note the symptoms like # relays clicked, frying noise, blinking lights,
station sound, OSD, etc.*
2. Check power handling devices or common failures such as the Hori-
zontal, Vertical, Audio, and Video output ICs for shorts.
3. Narrow the problem to a board
4. Isolate the problem to the circuit using the descriptions in the protec-
tion circuitry diagrams that follow.