Bang & Olufsen BeoLab 5 6881, Service Manual

Page: 15 / 38

The main chassis in the back-up suitcase, is setup as a EU version. If it should be
used in a JPN or US product, it will need to be converted. See page 6.4.
Service tips
Symptom:
The loudspeaker does not switch on, and the stand-by diode is always red.
Cause:
The amplifier is in protection-mode. The cause can be to high a load due to for
instance a disconnected/broken loudspeaker unit or NTC-PCB. The cause can also
be an internal fault in the main chassis.
Solution:
Check the load from the unit (b.m.o. an Ohm-meter) and replace the loudspeaker
unit, NTC-PCB or main chassis by using the back-up suitcase which contains all
necessary parts for On-site service. (Does not contain lower woofer or transformer).
Bring the main chassis into service position, and mount the complete lens again,
this way you can check the connection all the way through the lens. When the
chassis is in service position disconnect P3 on PCB6. On this plug you will be able
to check the tweeter and midrange unit, with a digital multimeter.
Service tips, English 5.1
Between red and orange there should be 5.7 ohm (midrange)
Between green and yellow there should be 3.0 ohm (tweeter)
The LB and UB can be measured directly on the units, after disconnecting the plugs.
The LB should measure 3.1 ohm
The UB should measure 5.0 ohm
All four NTC resistors should measure 470Kohm.
Note!
A thermal overload shuts down the BeoLab 5. Disconnect the mains for a few
seconds to reset BeoLab 5.