Bang & Olufsen BeoLab 12-3, Service Manual

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Troubleshooting 2.5
Speaker unit check
Measure the impedance of the speaker unit to determine if the fault is caused by a
defective speaker unit.
It is recommended to measure on the terminals on the speaker unit. The speaker
unit must be disconnected from the product.
! Pay special attention to the gasket on the speaker unit.
Speaker unit Nominal value Limits
Tweeter 6.6 ohm 5.6 - 6.7 ohm
Midrange 3.6 ohm 2.6 - 4.7 ohm
Woofers 6.7 ohm 5.6 - 6.7 ohm
If the speaker unit is outside the limits, it is defective and must be replaced.
Under normal conditions it is not necessary to replace the gaskets on the speaker
unit, unless they have been damaged by accident.
NTC module test
Measure the resistance of the NTC module to determine if the fault is caused by a
defective speaker unit or the NTC module.
It is recommended to measure on the terminals on the back of the speaker unit.
The NTC module must be disconnected from the product.
! Pay special attention to the gasket on the speaker unit.
The resistance of the NTC module at 22ºC (72ºF) is approximately 470K ohm (the
NTC resistor must be disconnected from the wire).
If the NTC module is outside the limits, it is defective and must be replaced.
Under normal conditions it is not necessary to replace the gaskets on the speaker
unit, unless they have been damaged by accident.
! The shown speaker is
only an example
! The shown speaker is only an example