Cambridge Audio 540A V2 - Input PCB Schematic (Protection Circuitry)

Cambridge Audio Azur 540A V2.0 Amplifier
AP17649/5 Input PCB Schematic (Protection Circuitry)
+5Volts
R66
1k
For 1mA
R64
10k
R67
100R
R65
2R7
DGND
3
2
1
84
U8:A
LM393
D7
1N4148
+5V
Speaker short circuit tester
R69
4k7
(Open Collector Output)
Senses a DC resistance of 2 ohms or less
D6
1N4004
PIC VI/Short
C43
100N 50V X7R
Speaker Test
DGND
+5V
SW1:B
SW-DPDT
TAPE
SPEAKER B SWITCHING (for relay)
Speaker Test
Speaker A Relay
Unreg for Relays
1
2
3
4
5
6
CN11
2,5MM 6W ST HEADER
To Speaker PCB CN1
PIC Standby Relay
Unreg for Relays
DGND
1
2
3
CN7
2,5MM 3W ST HEADER
R57
220R 2W Carbon
R108
220R 2W Carbon
PIC VI/Short
PIC DC
PIC CLIP
PIC Temp
Speaker A Relay
PIC Standby Relay
1
2
3
4
5
6
7
8
CN6
2,5MM 8W ST HEADER
To PIC
GENERAL NOTES
1.
2.
3.
4.
5.
Mains󰼿PCB󰼿Control
Speaker󰼿PCB󰼿Control
PIC󰼿Protection󰼿signals
Speaker󰼿Cable󰼿Short󰼿Circuit󰼿Detector
LK103
LK10MM
LK14
LK10MM
LK15
LK10MM
5
6
7
U8:B
LM393
LK102
LK10
LINK15MM
LK46
LK11
LINK15MM
LK45
LK10MM
1
2
3
4
5
CN4
2,5MM 5W ST HEADER
DGND
PIC VI/Short
PIC DC
PIC CLIP
Temp Sense
R116
10k
R115
10k
DGND
+5V
PIC Temp
R63
910R
910 / (910 + 10k) with ZP221A501E
voltage gives 100deg C cutout
+5Volts
Temp Sense
R71
4k7
R70
10k
R117
4k7
Open Collector Output
Q8
BC337
LK39
LK10MM
LK38
R68
100k
R62
no stuff
C108
100N 50V X7R
C107
100U 16V EL
DGND
+5V
Rev3:󰼿R65󰼿Changed󰼿from󰼿10R󰼿to󰼿8R2
Rev4:󰼿R65󰼿Changed󰼿from󰼿8R2󰼿to󰼿4R7
Rev5:󰼿R65󰼿Changed󰼿from󰼿4R7󰼿to󰼿2R7
86-756-8687998
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