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