Bang & Olufsen BeoSound 9000 MKIII, Service Manual

Page: 10 / 97

Explanation of diagram 2.1
Explanation of diagram
Type numbers of transistors and ICs are indicated on the diagrams. If the position
is followed by an asterisk the spare part number must always be used because the
component in question has been specially selected, e.g. IC4*.
Component print and coordinate system
The largest PCBs have component prints and a coordinate system on both the
primary and the secondary side.
On the diagrams every component has a coordinate number.
This indicates in which coordinate on the PCB the component is situated. The
coordinate numbers are written in smaller print types than the position numbers.
= C27 is placed on the primary side in coordinate 1A.
= R10 is placed on the secondary side in coordinate 2B.
Control circuit
In certain control circuits the active mode is indicated by a function term or by an
abbreviation. This may be e.g. ST.BY. = low in the stand-by mode or ST.BY. = high
in the stand-by mode.
Wiring connections
The wiring connections on the diagrams are assembled in ‘bundles’.
The individual wires are provided with one of the following codes:
INTERNAL CONNECTION ON
ONE DIAGRAM PAGE
Internal connections on a diagram page are indicated by a number.
The bend of the wire indicates in which direction the other end of the wire is
found.
CONNECTION TO ANOTHER
DIAGRAM PAGE
A connection to another diagram page is indicated by a number as well as by a
letter of the diagram to which the connection leads.
Ground symbols
Three different ground symbols are used in the set.
= Ground
= Chassis
= Coarse ground
Symbol of safety components
When replacing components with this symbol, components with identical part
numbers must be used. The new component must be mounted in the same way
as the one replaced.
DIAGRAM A DIAGRAM C