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ALPHA 7/8/9 CD SERVICE MANUAL
ALPHA 7/8/9 CD SERVICE MANUAL
Test Points Marked on Circuit Diagram Only
Test Points
Clock Output to mother board. 16.9344MHz +/- 40ppm, 4V to 5V peak to peak square wave.
17MHz
Analogue ground point.
AGND
Digital audio mute input on SK203. 0V=off, 5V=Mute.
AMUTE
Serial Data clock input on SK203. Sony format.
CK
DA
Serial Data data input on SK203. Sony format.
Crystal clock override. A 16.9344MHz HCMOS clock can be injected from an external source.
CLKSYNC
De-emphasis select input on SK203. 0V=off, 5V=On.
DEEM
Digital ground point.
DGND
Left channel audio output at SK1. Measure d.c. offset at switch-on and after 1 minute, see specifications.
LOUT
Serial Data LR input on SK203. Sony format.
LR
MUTERLY
Mute Relay Voltage. Equal to RLYPWR voltage when output is muted and 0V d.c. +0.5V,-0.0V when
output is un-muted.
N15
Regulated analogue supply. -15V d.c. +/- 0.6V.
-18.45V d.c. +/- 0.5V supply input on SK204 for analogue.
N18V
+5V d.c. +/- 0.3V digital filter supply input on SK204.
P5V(0)
+5V d.c. +/- 0.3V PWM noise shaper supply input on SK204.
P5V(1)
Regulated clock supply. +5V d.c. +/- 0.3V.
P5VCLK
Regulated analogue supply. +15V d.c. +/- 0.6V.
P15
P18V(0)
+18.45V d.c. +/- 0.5V supply input on SK204 for analogue.
+18.45V d.c. +/- 0.5V supply input on SK204 for clock and latch.
P18V(1)
Power ground point. Used by mute relay only.
PWRGND
Mute relay control from PIC micro on SK203.
RA0
Control lines from PIC micro on SK203.
RB0-RB7
DAC reference voltage, left channel. +5V +/- 0.3V.
REFL
REFR
DAC reference voltage, right channel.
+12V d.c. +/- 1V supply input for mute relay on SK204.
RLYPWR
Right channel audio output at SK1. Measure d.c. offset at switch-on and after 1 minute, see
ROUT
specifications.
Left d.c. servo voltage. -10 to +10V d.c.
SRVL
Right d.c. servo voltage.
SRVR
Clock used by latches. 4V to 5V peak to peak square wave at 16.9344MHz.
SYSCLK
Measurement Information
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