Bang & Olufsen BeoLab 12-3, Service Manual

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2.14 Fault flow chart
Fault symptom:
No sound from any speaker
Green LED indication
Possible causes:
Line switch settings
Defective PCB04, SMPS
Defective PCB41*, V.CON
Defective PCB30, Digital Sound Engine
Confirm -20V_
Vdrive at PCB35, P3
pin 1 (x3)
OK?
Confirm -20V_
Vdrive at PCB41*,
P1 pin 1
OK?
**
Connect the cable
for ServiceTool to
the service
connector. Any
useful information?
No
Yes
C3V V.drive
control at PCB41,
P3 pin 1
OK?
Replace defective
PCB41, V.CON
Replace defective
PCB04, SMPS
Disconnect W4
from PCB41 P3.
C3V V.drive
control at PCB30,
P8 pin 12
OK?
Replace defective
PCB41, V.CON
Replace defective
PCB30, Digital
Sound Engine
Replace the
suspected module
related to the error
log
Confirm that line
switch settings is
correct
OK?
Set line switch
settings
Confirm:
+33V at PCB04, P3
pin 4
-33V at PCB04, P3
pin 2
OK?
Replace defective
PCB30, DSE
Disconnect W3
from PCB04, P3.
C33V at
PCB04, P3 pin 4
-33V at PCB04, P3
pin 2
OK?
Replace defective
PCB04, SMPS
Fault in one of the
three PCB35,
ICEpower
amplifiers.
Disconnect one by
one and replace the
defective module
PCB04, P4, pin information - see next page
PCB30, P8, pin information - see next page
** PCB41 - Not present in all versions.
In this case follow the dashed line.
* PCB41 - Not present in all versions.