SCD-XA777ES - Sony Audio Service Manual (repair manual). Page 21

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The communication between microcomputer and main ICs (self-
diagnosis) and the fluorescent display tube all lit are checked.

Checking Method:
1. After setting the test mode, rotate the 

[        AMS        ]

 dial to

select “92. SET CHECK” and press the 

[        AMS        ]

 dial

to enter.

2. When  “SET TEST  START” is displayed, rotate the

[        AMS        ]

 dial clockwise by 1 click to select “0. IC&FL

CHECK?” and press the 

[        AMS        ]

 dial to enter.

3. A checking will start automatically, and “0. IC&FL CHECK”

will be displayed. (Checking time is about 3 seconds)

4. After IC communication check, all segments of fluorescent

display tube will be lit. At this time, check visually for a skipped
character.

5. At successful completion of check, “0. IC CHECK OK” is

displayed. In this case, no error exists in the IC interface. Pro-
ceed to 4-2. AUTO CHECK.

The check mentioned above tests the communication from micro-
computer to main ICs. Even if the check successfully finished, the
IC to be checked is not always normal. Consider it for reference
only.

6. In case of an IC communication error, the following display

will be given during the checking. Possible causes of error are
as listed below.

Error display

Causes  (typical example)

DVD DEC. ERROR

1. IC701 (SACD decoder) is faulty
2. IC701 pin <znv (XRST) does not go “H”

• IC901 pin rf (XDIS) does not go “H”
• IC902 (expander) is faulty

3. 768fs (33.86688 MHz) is not present to

IC701 pin <znm (XTAL)
• IC811 (3-multiplying circuit) is faulty
• Clock signal 256fs is not sent from

MOTHER board (CN302 pin 4)

• CN302 pin 1,5 (D.FGND) and pin 3

(+3.3V) are open or shorted

• CN302 and FFC connection is loose,

or FFC is disconnected

DVD DRAM ERR

1. IC706 (D-RAM) is faulty
2. IC701 pin <znv (XRST) does not go “H”

• IC901 pin rf (XDIS) does not go “H”
• IC902 (expander) is faulty

3. Faulty communication line between

IC701 and IC706
• Data line, address line, WE, etc.

4. D903 (1SS367) is faulty

CD DSP ERROR

1. IC509 (CD DSP) is faulty
2. 768fs (33.86688 MHz) is not present to

IC509 pin ua (XTAL)
Same as cause 3 of DVD DEC. ERROR

3. IC509 pin 2 (XRST) does not go “H”

• IC901 pin rf (XDIS) does not go “H”
• IC902 (expander) is faulty

EEPROM ERROR

1. IC903 (EEPROM) is faulty

Error display

Causes  (typical example)

PRAWN DRAM ERR

1. IC808 (D-RAM) is faulty

*1

2. IC801 (DSD decoder) is faulty
3. 768fs (33.86688 MHz) is not present to

IC801 pin qa (MCKI)
Same as cause 3 of DVD DEC. ERROR

4. IC801 pin 9 (XRST) does not go “H”

• IC901 pin rf (XDIS) does not go “H”
• IC902 (expander) is faulty

5. Faulty communication line between

IC801 and IC808
• Data line, address line, WE, etc.

6. D904 (1SS367) is faulty

D+3.3V is not present to IC808

RF AMP ERROR

1. IC001 (RF AMP) is faulty
2. Loose connection between CN503 on

MAIN board and CN001 on RF board,
or FFC disconnection
CN503 pin ql (CLK RF), pin w; (DATA
RF) and pin wa (SDEN) must be checked

*1 DSD decoder is also checked.

Causes Common to Each IC:
1. Faulty communication line between microcomputer and each

IC.
Disconnected patterns, floating series resistors, bridge, etc.

2. Faulty IC supply voltage.

Particularly, check D+3.3V voltage. (D+5V for display mi-
crocomputer)

3. Faulty microcomputer communication port to each IC

In case of more than two errors, the error display is switched over
one after another, thus making the reading difficult.
In such a case, press again the 

[        AMS        ]

 dial to make a

recheck for error reading.

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