The PNL1 UCOM (IC8406) of this unit always monitors various power voltages and will shut the secondary power source off
immediately once an error is detected.
In such a case, the MIDI START/STOP (WAKE UP) LED flashes.
g Power monitoring circuit
The name of a power source denotes its voltage. (Example: V+3R3A, denoting 3.3 V)
g Monitored power voltages
! An error-alert signal (FAULT_DET) is issued by the voltage-monitoring block.
The FAULT_DET signal is High level (+3.3V) in normal state, or it is Low level (0V) in abnormal state .
The PNL1 UCOM detects the state.
! The PNL1 UCOM issues a signal for interrupting SW POWER SUPPLY (ANA_P_CON, DIGI_P_CON) if an error is detected.
g Outline of the detection system
Caution : Each time before turning the unit ON, make sure that each power-supply IC is not short-circuited to GND.
If any voltage is abnormal, that error will be detected by the voltage-monitoring program after it is started after a usual
startup of the unit. Then the V+12M, V+15U, V-15U, V+5U power from SW POWER SUPPLY will be stopped.
Identify which power-supply IC is defective, by duplicate drawing and inserting of the power cord while monitoring each
voltage with an oscilloscope. Check the value of each voltage immediately before stopping power supply.
g Diagnostic procedure
Upper limit monitoring
V+3R3D V+3R3D_MDSP V+3R3D_CLK V+3R8D_AM V+5D
V+5D_MDSP V+1R0_CVDD V+1R0_CVDD1 V+1R1_AM_CORE V+1R285D
V+1R325_AM_MPU V+1R35_MDSP_DDR V+1R5_AM_DDR V+1R8D_MDSP V+9LED
V-15A V+5A V-7HP
Lower limit monitoring
V+3R3D V+5D V+9LED V+15A V+5A
MAIN Assy SW POWER SUPPLY
UCOM Assy
FAULT_DET
!
ANA_P_CON
(V±15U, V+5U control)
!
DIGI_P_CON
(V+12M control)
IC8406
PNL1 UCOM
Voltage monitoring
Block
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