Sequential prophet 5 - Page 51

Component designators include three items of information:
COMPONENT CLASS
PCB or ASSEMBLY NUMBER
COMPONENT NUMBER
COMPONENT CLASS is symbolized by standard letters, for example. U for integrated circuit, RT
for temperature-sensitive resistor, and DS for indicator.
PCB or ASSEMBLY NUMBERS are:
1 RIGHT CONTROL PANEL
2 LEFT CONTROL PANEL
3 COMPUTER BOARD
4 VOICE BOARD
COMPONENT NUMBERS are either sequenced according to their position on a PCB. or according
to the position of its designator (callout) on the pictorials (PA documents).
Generally, the schematics (SD documents) group together components electrically feliledio one
another, even though they may actually be located on different PCBs. For example, the POT MUX
circuitry is implemented across PCBs 1 and 2 but is drawn on a single sheet (SD211). In such cases
you can rely on its designator to indicate the PCB on which a component is located. You may then
easily find it from the pictorials.
PCB 4 components are designated somewhat differently from the rest This PCB holds five essen¬
tially identical, parallel circuits. So. parallel passive components are given the same designator. For
example, there are five R4122s — one per voice. Individual active components are still individually
designated.
For clarity, power supply decouplers are not identified on each voice pictorial. Instead they will
be found on PA 410, with other (non-voice) PCB 4 components.
A note on our rendering of bus lines and continued signals: We bus lines together to prevent long,
confusing parallel runs. For example, DATA BUS lines are drawn as a single line, with individual lines
symbolized DBO. DB1, DB2... where the bus "fans-in" or “fans-out" at a device. If there are no DB
(or A. ADDRESS BUS) symbols, the bus lines are assumed to connect according to the device pm
names.
Although bussing wires reduces the number of interrupted signals, some breaking of lines on a
page or continuation of signals between pages cannot be avoided. At these points you will find
a symbol such as:
5 none
6 POWER SUPPLY BOARD (PSB)
7 CHASSIS ASSEMBLY
B IAS 1A C V-Q^> R499
This example means that the BIAS 1A control voltage signal goes to R499 on sheet F (SD411). The
sheet letter symbol is found in its margin.
Power and ground connections for multi-device packages have been shown on the first device in
the package, except where the first device is not presently used.
Unless otherwise indicated resistances are in ohms and capacitances are m microfarads.
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