Test Mode - Sony SDP-EP70 Service Manual

Self-Diagnosis and Test Mode
This unit is provided with a "self-diagnosis and self-recovery func-
tion" which detects DSP errors and automatically recovers the unit,
and a test mode for performing operation checks during repairs.
1. Main Functions
• DSP self-diagnosis and self-recovery function
• Self-diagnosis for servicing and error message display
• Display of history of past DSP errors
• Various operation check mode
• SRAM, EEPROM check function
• Initialization (Differs according to country)
VOLUME LED
2. Entering the Test Mode
1. While pressing the AC-3 RF button and DIGITAL 2 button
simultaneously in the power OFF state, press the POWER but-
ton.
2. When the VOLUME LED starts blinking, release these buttons.
The self-diagnosis for servicing will be executed, and the opera-
tion check mode will be set.
(NOTE: Performing initialization will erase the error history.
Do not therefore press the wrong buttons. For details, refer to
"5. Initialization" on page 15.)
SECTION 3

TEST MODE

3. Self-diagnosis Mode for Servicing/Display of
History of DSP Errors
3-1. Self-diagnosis Mode for Servicing
Before entering the test mode, first the following self-diagnosis pro-
gram for servicing will be run.
1. Checks if unintended buttons are being pressed
2. Checks EEPROM (External memory device) operation
3. Read/write test of DSP external memory (1M SRAM)
4. Checks and displays history of various DSP abnormal operations
• When an error is detected:
The error message is displayed for about 8 seconds on the fluo-
rescent display tube, it is switched to "MPEG/DOLBY DIGITAL",
and the operation check mode is set. (See Table 1.)
When several errors occur at the same time, only the first error
detected will be displayed.
• When no error is detected:
"Ver. main X. X mpeg X. X" will be displayed, and the operation
check mode will be set. (X. X means its version No.)
Table-1:
Error Message/Fluo-
rescent Display Tube
VOLUME LED blinks
and fluorescent display
tube is OFF*
EEPROM read error!
EEPROM write error!
S-RAM access error!
DSP error detected!
*NOTE:
Refer to "6. Check of Pressing of Unintended Button" on page 15.
– 13 –
Possible Reasons
An unintended button is pressed, or connec-
tion fault of flexible board between MAIN
board and DISPLAY board.
Soldering fault or malfunction between IC202
(MAIN board AT24C02) and IC201 (MAIN
board microprocessor).
Reached end of IC202 (MAIN board
AT24C02) writing life or incorrect insertion
of part.
Soldering fault between IC422 (MAIN part 1M
SRAM) and IC423 (MAIN board SSP424023)
When a DSP error is detected
(Refer to "3-2. Display of History of Abnormal
DSP Operations".)