1.3. Power Supply Voltage Abnormalities
1.4. I2C Communication Line Abnormalities
Check the output voltage FRONT PCB form POWER PCB
Are there large deviations in the output voltage?
[
N1012 : 1pin
] = +3.3 ± 0.5V, +3.3V_UCOM
[
N1012 : 2pin
] = +3.3 ± 0.5V, +3.3V_D
[
N1012 : 4pin
] = +5V ± 0.5V, +5V_NET
[
N1012 : 6, 7pin
] = +5 ± 0.5V, +5V_USB
[
N1012 : 10pin
] = +5 ± 0.5V, +5V_D_AUDIO
[
N1012 : 12pin
] = -5 ± 0.5V, 5V_D_AUDIO
There is a power relay [
S4001
] or relay operation circuit abnormality.
Replace the Power PCB if repair proves too complicated.
Is SMPS [
U5004
] operation stopped while power is being supplied
to the Power PCB unit?
Normal voltage for the [
C5003 : + terminal
] is +6V or more.
When the power switch is on, does the power relay [
S4001
]
operate ([3 and 4 pins conduct electricity])?
Are any of the Power PCB power supply ICs functioning abnor-
mally?
If the input voltage of all the power supply ICs is 0V, proceed to
"
NO
".
Replace any defective parts or the Power PCB.
There is an abnormality in the SMPS circuit.
Replace the Power PCB if repair proves too complicated.
The main transformer fuse is burnt out or there may be some other
abnormality.
Replace the power transformer.
NO
NO
NO
NO
YES
YES
YES
YES
1.4. I2C Communication Line Abnormalities
Check the output signal. FRONT PCB
SYSTEM uCOM[
U1004 : 106(SDA), 107(SCL)pin
]
Is there an abnormality in the "
Hi
" (3.3V) or "
Lo
" (0V) level?
The [
106 (SDA) and 107 (SCL) pins
] of the System uCOM send a signal to each I2C device at startup. If
each I2C device does not return an ACK signal, System uCOM operations latch.
Check the connection.
Has a contact failure occurred or is a connector missing?
DIGITAL PCB : [
N3002
] to AUDIO PCB : [
N1001
]
NO
There may be a soldering defect in the Digital PCB pull-up resistor [
R1240, R1239
] or the System uCOM
[
U1004: 106 (SDA) or 107 (SCL) pins
] are defective.
Replace the System uCOM [
U1004
] or the Digital PCB.
Check if the connection is as indicated in the wiring diagram and adjust the FFC wiring if necessary.
If this does not re-establish contact in the wiring, replace the FFC or the circuit board which the con-
nectors are mounted on.
YES
YES
Check the output voltage. AUDIO PCB
Are there large deviations in the output voltage?
[
U1007
] = +5.25V, +5.25V
[
U1026
] = +3.3V, +3.3D1
[
U1026
] = +3.3V, +3.3DAC
[
U1028
] = +1.3V, +1.3D1
Check that the internal wiring is connected correctly. If no abnormalities are apparent, remove the AC power supply for around 1 minute to allow electricity to discharge from the internal wiring, then reconnect
the power supply and turn the unit on.
NO
Before Servicing
This Unit
Electrical
Mechanical
Repair Information
Updating
49
