Sony XM-7557 Service Manual ▷ View online
5
6
7
1
Five screws
(BTP3x12)
2
Four screws
(P4x40)
9
Four screws
(P3x10)
!¡
Six screws
(P3x10)
0
Screw (BTP3x8)
!¢
Two insulating sheets
(AMP)
!£
Sub heat sink
(Amplifier)
8
Two screws
(P3x14)
!∞
Two screws
(P2x10)
!™
Three screws
(P3x6)
3
Six screws
(BVTP3x14)
4
Two Retainers
5
Two screws (BVTP3x10)
6
Power board
7
Amplifier board
!§
LED board
!¶
LED holder
8
Three screws
(BTP3x8)
9
Screw (BTP3x8)
0
Side plate (R)
3
Two screws
(BTP3x8)
!¢
Auto fuse
(F901 to F904)
4
Bottom plate
2
Three screws
(BTP3x8)
1
Three screws
(BTP3x8)
!∞
Screw (BTP3x8)
@¢
Screw (BTP3x8)
!ª
Screw (BTP3x8)
@∞
TR board
@º
Sub 2 board
@¡
Sub 1 board
@§
Fan motor block
!§
Filter board
6
Screw (BTP3x8)
!™
Screw (M4)
!£
Cover
!¡
Screw (M4)
5
Three screws
(BTP3x8)
7
Side plate (L)
!•
Screw (BTP3x12)
!¶
CNP710 (10P)
@™
CNP803 (3P)
@£
CNP708 (2P)
SECTION 3
DISASSEMBLY
Note:
Follow the disassembly procedure in the numerical order given.
3-1. SIDE PLATE,SUB 1/SUB 2 AND FILTER BOARD
3-2. AMPLIFIER/POWER BOARD AND LED BOARD
7
SECTION 4
ELECTRICAL ADJUSTMENT
IDLING CURRENT ADJUSTMENT
• Perform adjustments in the HI-VOLTAGE mode.
1 Adjustment point
Semi-fixed resistors VR101, VR201, VR301, VR401, VR501,
VR502 of amplifier board
VR502 of amplifier board
2 Precautions on adjustments
1. Set the RCA input terminal to open.
2. Apply a voltage of 14.4V between the +12V terminal, REMOTE
1. Set the RCA input terminal to open.
2. Apply a voltage of 14.4V between the +12V terminal, REMOTE
terminal, and GND terminal.
3. Rotate the above semi-fixed resistors completely in the counter-
clockwise direction while observing the component side.
4. Check that the voltage at the adjustment point becomes 0 mV in
step 2.
5. Fine adjustments may be required according to the characteris-
tics of the MOS-FET used.
• When adjusting the idling current
Rotating the semi-fixed resistor in the clockwise direction:
Increases the idling current
Rotating the semi-fixed resistor in the counterclockwise direction:
Increases the idling current
Rotating the semi-fixed resistor in the counterclockwise direction:
Decreases the idling current
* Take note that rotating excessively in the clockwise direction
will increase the idling current suddenly.
3 Approximate adjustment values
Adjust as follows so that the following voltages become
1.2 to 0.3 mV around 0.7 mV .
1.2 to 0.3 mV around 0.7 mV .
FL channel :
Voltage between TP7 and TP6: Use VR101 of the amplifier board
FR channel :
Voltage between TP7 and TP5: Use VR201 of the amplifier board
RL channel :
Voltage between TP7 and TP4: Use VR301 of the amplifier board
RR channel :
Voltage between TP7 and TP3: Use VR401 of the amplifier board
Voltage between TP7 and TP6: Use VR101 of the amplifier board
FR channel :
Voltage between TP7 and TP5: Use VR201 of the amplifier board
RL channel :
Voltage between TP7 and TP4: Use VR301 of the amplifier board
RR channel :
Voltage between TP7 and TP3: Use VR401 of the amplifier board
SUBWOOFER Channels :
First, adjust so that the voltage between TP1 and TP2 becomes
1.2 to 0.3 mV around 0.7 mV using VR501 of the amplifier
board.
Next, adjust so that the voltage between TP1 and TP2 becomes
2.4 to 0.6 mV around 1.4 mV using VR502 of the amplifier
board.”
First, adjust so that the voltage between TP1 and TP2 becomes
1.2 to 0.3 mV around 0.7 mV using VR501 of the amplifier
board.
Next, adjust so that the voltage between TP1 and TP2 becomes
2.4 to 0.6 mV around 1.4 mV using VR502 of the amplifier
board.”
Connection :
TP7
TP1
TP6
TP5
TP4
TP3
TP2
TP1
TP5
TP4
TP3
TP2
TP1
(FL-CH)
(FR-CH)
(RL-CH)
(RR-CH)
(SUB WOOFER)
(SUB WOOFER)
(FR-CH)
(RL-CH)
(RR-CH)
(SUB WOOFER)
(SUB WOOFER)
(SUB WOOFER)
Digital voltmeter
JW230
JW307
VR502
TP3
TP4
TP5
TP6
TP7
TP1
TP2
VR501
VR401
VR301
VR201
VR101
Adjustment Location
– AMPLIFIER BOARD – (Component side)
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