Repair Tips - Bang & Olufsen BeoSound 4 2851 Service Manual

4.

Repair tips

Repair tips
CD
Exchange of the microprocessor and PCB2
Exchange of software EEPROM on PCB6
Replacing of both PCB6 and EEPROM 6IC6
The diodes and the laser are very sensitive to static electricity. Damaging the diodes
or laser may reduce their lives dramatically. So be sure, that the workstation is
protected against static electricity.
The product may not be connected to the mains, when the CD mechanism or
96Module is removed.
Normally, the CD will find focus first, and when that has been found, it will start
the turntable motor. This means that if the motor cannot start, the reason may be
that focus has not been found.
When replacing the PCB6 remember to move the EEPROM 6IC6 from the
defective PCB6 to the new PCB6, because it contains valuable data (serial no. and
PIN code etc). The data is not transferred to the new module until you have been
in contact with the PIN-code protection or after  hours of connection to the
mains. This means that you can try out a new PCB6 without transferring the
product's serial no. etc.
Note!
When the serial number has been transferred to the microprocessor, it can only be
used for this specific product; it must go back to Bang & Olufsen's module repair
department as an exchange module to be erased again. If the product functions
are OK, and the PIN-code protection is also OK; there is no need to test the
functionality of the PIN-code protection.
When exchanging the EEPROM on PCB6, the data from the microprocessor will be
written into the EEPROM, when selecting any source e.g. RADIO.
It is possible to borrow an EEPROM from another BeoSound 4 to test, if there is
suspicion of a fault in the original EEPROM. The EEPROM will always adopt the
data from the main microprocessor.
If both PCB6 and the EEPROM 6IC6 need to be replaced it is necessary to have
them pre-programmed from Bang & Olufsen with the correct serial no., otherwise
they will not work. Please contact Bang & Olufsen.