Input Pcb Schematic (Protection Circuitry) - Cambridge Audio 540A V2 Service Manual

Speaker Cable Shor t Circuit Detector
LK14 LK103
+5V
LK10MM LK10MM
Speaker Test
D6
1N4004
Mains PCB Control
CN7
PIC Standby Relay
3
R108
Unreg for Relays
2
1
220R 2W Carbon
2,5MM 3W ST HEADER
DGND
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Cambridge Audio Azur 540A V2.0 Amplifier
Speaker short circuit tester
Senses a DC resistance of 2 ohms or less
+5Volts
C43
R66 R64
100N 50V X7R
1k 10k
U8:A
For 1mA
3 LM393
1
2
R67 R65
100R 2R7
R62
no stuff
+5Volts
R71 R70
4k7 10k
U8:B
LM393
5
7
PIC Temp
6
R68
100k
R63
910R
910 / (910 + 10k) with ZP221A501E
voltage gives 100deg C cutout
AP17649/5 Input PCB Schematic (Protection Circuitry)
Speaker PCB Contr ol
R69
4k7 SPEAKER B SWITCHING (for relay)
(Open Collector Output)
SW1:B
D7
PIC VI/Short
SW-DPDT
1N4148
TAPE
Unreg for Relays
LK11
LINK15MM
LK102
CN4
1
2 LK38
Temp Sense
3
PIC VI/Short
4
5
PIC CLIP
R116
2,5MM 5W ST HEADER
10k
DGND
GENERAL NOTES
1. Rev3: R 65 Changed from 10R to 8R2
2.
Rev4: R 65 Changed from 8R2 to 4R7
3.
Rev5: R 65 Changed from 4R7 to 2R7
4.
5.
Speaker Test CN11
Speaker A Relay
LK10
1
LK46
2
LINK15MM
3
R57
4
5
220R 2W Carbon
LK45 6
LK10MM
2,5MM 6W ST HEADER
To Speaker PCB CN1
LK15
LK10MM
C108
100N 50V X7R
DGND
PIC Pr otection signals
R115
10k
R117
PIC DC
4k7
Open Collector Output
Q8
+5V
BC337
LK39
PIC Temp
LK10MM
PIC VI/Short
PIC Standby Relay
PIC DC
PIC CLIP
Speaker A Relay
C107
100U 16V EL
DGND
CN6
1
2
3
4
5
6
7
8
2,5MM 8W ST HEADER
To PIC
8