Bang & Olufsen BeoLink User Manual page 37

Trouble
No sound and no operation
No sound but operation OK
Play only at half volume
MASTER LINK
Possible cause
The product is connected to the mains and the stand-by diode is on.
If the above is OK, do as follows:
- Meter data+ (pin 2) relative to ground
- Meter data- (pin 1) relative to ground
- Where no transmission, +/- 200 to 300 mV should be metered.
- When data is being transmitted, 0V should be metered.
Measurement with oscilloscope.
Meter the following:
No transmission ———————————— + 0.25
———————————— 0
———————————— -0.25
Transmission
If data- and data+ are not as shown at "No transmission" and are unable
to transmit, the fault may be in the main room's BeoVision or BeoSound,
since it is one of these two units that supplies this voltage.
Please note that in setups with a BeoLink Converter it is always the
Master Link driver that supplies the voltage. If there are two Master Link
drivers, one of them will, when connected, configure itself as being the
one that supplies the data voltage.
The fault is found by applying the method of exclusion. If the fault is not
in one of the Master Link drivers, there is another product that pulls data
low or high respectively. Alternatively there could be a cable fault or a
connection fault. Data errors can also be displayed in service mode; see
the section on service mode.
If data is OK, proceed with the measurement of the supply voltage which
should be as stated under the specifications. If the voltage is not OK,
apply the method of exclusion until the faulty product or the faulty
connection has been found.
The data and supply voltages are in this case OK. Meter the signal levels
at pins 13 to 16 in relation to the stated specifications. If the signal levels
are OK, the fault is in the link room product, perhaps in the converter
box, or it may be a faulty cable or connection.
One of the balanced audio signals has dropped out.
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