Sharp 20F550, Service Manual

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Service Mode Overview
1. Service mode is entered by SERVICE key input or CH-UP +VOL-DOWN input during reset.
2. Service mode is cleared by entering SERVICE key command during service mode.
3. If key input port (SERVICE) input is LOW, then it is in service mode.
4. During key input port (SERVICE) input is LOW, clearing service mode by key input SERVICE is disabled.
5. Service mode can be switched to 4 modes as follows by key input MENU;
SERVICE MODE
6. AFT processing is disabled during service mode. PLL setting data is set to fo data.
7. All user data are set to default during service mode. FAO and SPEAKER user settings are off and on respectively
in service mode. Energy Save is off.
8. Sleep timer, View timer, On timer and OFF timer are inactivated in Service mode.
9. Sound is muting in service mode except at Adjustment Items V20, M01, M03, M04, M05, and M06.
Adjustment mode
Setting mode
First mode of service mode when SERVICE key is
pressed.
First mode of service mode when local key
CH-UP + VOL-DOWN is pressed after MCU reset.
Option mode
Check mode
20F550