Sony XBR-55X850D Service Manual page 23

FLOW
1-2-1. NO POWER U-COM FAILURE
Case: BMFW2 structure
START
no
Check C9117 Voltage.
Is the voltage >3.0V?
yes
no
Check C9129 Voltage.
Is the voltage >3.0V?
yes
Check OPWRSB no
R9179 Voltage.
Is the voltage 0V?
yes
Check POWER_ON no
IC9017 #pin19
Is the voltage >3.0V?
yes
Check P_ON_LNB no
IC9017 #pin15
Is the voltage >3.0V?
yes
XBR-55X850D/855D/857D, 65X850D/855D/857D, 75X850D/855D/857D
Check +3.3V_STBY
C9006, CN9000 #24pin
Check DC_OFF_DET
IC9000
SOC
Muffin
problem
Try AC Off and On after few minutes.
If #pin19 keep Low, change IC9017.
If #pin19 goes High few seconds and downs to Low,
Check 12.5V Line (G board, LD or IC9007).
Change IC9017
no
Check MAIN_VCC
R9175 Voltage.
Is the voltage >1.6V?
yes
no
Check P_ON_VBUS
IC9017 #pin11
is >3.0V?
yes
no
Check P_ON_#1
IC9017 #pin13
is >3.0V?
yes
no
Check PGOOD_1
R9173 Voltage.
Is the voltage >3.0V?
yes
Continue next page...
TROUBLE SHOOTING
Check 12.5V Line
(G board, LD or IC9007).
Change IC9017
Change IC9017
1-3 No POWER - DDCON/LDO
Check 1.0V DDCON (IC9008)
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