Bang & Olufsen BeoLab 12-3, Service Manual

Page: 18 / 60

2.12 Fault flow chart
Fault symptom:
The product is in protection
LED indicator is flashing orange
Possible causes:
Defective PCB35, ICEpower amplifier
Defective PCB48, NTC
Missing or faulty speaker calibration
Missing product ID
No
Yes
Disconnect the
product from the
mains
Disconnect W12
from PCB30, P9.
Confirm 500K
Ω
* at
W12 pin 1-2, pin
3-4 and pin 5-6
OK?
Measure the
temperature of the
two woofers/
midrange speaker
unit.
Seems similar/
normal ?
* Approximately 500K
Ω
at 22°C (72°F)
Defective PCB48,
NTC.
Follow W12,
measure/discover
and replace the
defective NTC unit
Replace defective
speaker unit.
Use ServiceTool to
calibrate the new
speaker unit
Defective PCB35,
ICEpower amplifier.
Replace and use
ServiceTool to
calibrate the new
module
Locate the overheated speaker unit and measure
the resistance (wires disconnected):
Woofer = 6.5
Ω
+/-
Midrange = 3.6
Ω
Tweeter = 6.5
Ω
OK?
Reconnect the
product to the
mains and connect
ServiceTool. Read
out product ID. Is all
product ID data
OK?
Type in all product
ID data from the
product label
Measure the
temperature of the
three amplifier
modules.
Seems similar/
normal?
Locate and replace
the overheated
amplifier module
Confirm voltages at
PCB04, P2:
pin 6 = 1V
pin 7 = 0V
pin 8 = 5V
OK?
One or more defective PCB35, ICEpower
amplifier. Disconnect, one at the time, PCB35 P1
to discover the defective module.
Replace and use ServiceTool to calibrate the new
module
Confirm voltages at
each PCB35, P1:
pin 10/11 = 0V
OK?
Defective PCB35,
ICEpower amplifier.
Replace and use
ServiceTool to
calibrate the new
module
Defective PCB30,
Digital Sound
Engine
Use ServiceTool to
perform a
calibration of all
amplifiers
OK?
PCB04, P4, pin information - see next page
PCB35, P1, pin information - see next page