Pioneer SX-6 Servicehandleiding - Pagina 12
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r Function Selector Control
The computer operation command input key
matrix for function selector control is outlined in
Fig. 1-6.
Key description
PHONO : Pin 10 of the IC (M74LS42P) refened
to above (*5) is switched to L level (*7), and
volume steps are displayed (00 - 31) in the
LED numeric display.
AUX : Pin 11 of IC (M74LS42P) switched to L
level (x8), and volume step also displayed in
LED numeric display.
FM: Pin 16 of IC (M54922P) switched to L level
as described above (x9).
AM: Pin 16 of IC (M54922P) switched to H level
as described above (x9).
LW/MW (PD6004) : AM band switching.
CLOCK (PD6007) : Time displayed in
LED
numeric display when pressed 1x19;. Display-
ed time is adjusted by TUNING
UP and
DOWN keys while the CLOCK key is depress-
ed. In the SX-7, time is displayed as long as
the POWER switch is left in the STD-BY
position.
(*7)
L
leuel here results in PHONO
indicator
being
turned on, and the PHONO channel of the elec-
tronic switch (PA4008) used by the FUNCTION
selector aleo being turned on.
(*8)
L leuel here results in the AUX indicator plus the
IC (PA4008) AUX channel being turned on.
(*9)
Depending on whether pin 16 of IC (M54922P) is
at L leuel or H leuel, and the leuel of pin 10 (L
leuel for PHONO) and, pin 11 (L level for AUX) of
IC (M74LS42P),
the AM-FM
switching
circuit is
actiuated, the AM or FM indicator tumed on, and
the IC (PA4008) AM or FM channel switched ON.
(*10)
A
500H2 pulse signal obtained by diuiding the
crystal oscillator signal (source of the synthesizer
reference signal) appears at pin 17 of IC (M54922P),
and is applied to the TC pin of PD6007 to actiuate
the cloch functions.
r
Volume Control (SX-7 and SX-61
Models SX-7 and SX-6 have been equipped with
an electronic volume control IC (PA5004). This IC
has the following 4 functions.
1. The gain is changed from -90d8
to OdB by
changing the voltage on the VOL terminal
(pin 12) from 0 to 3.2V.
2. The balance is changed continuously from right
channel only (-bV)
to center (0V) and left
channel only (+5V) by changing the voltage on
the BAL terminal (pin 9) from -bV to +5V.
3. Audio muting of approximately -25dB
is
applied when the MUTE terminal (pin 11) is
switched to L level.
Fig. 1-6
Switch key matrix for function selector
Fis. 1-7
Switch key matrix for volume control