Hitachi 28LD5200E Service Manual page 20

Power cannot be turned on (LED does not light)
Is the input voltage
applied to Power supply unit?
(CN5 [1][3])
Yes
Are the
voltages applied to
P804 [1][8]pins, P806[1]pin
and P808 [1][4][8][12]pins
of Power supply
unit?
Yes
Joint / Formatter PWB
Picture is displayed. But no sound
Check
Speaker terminal and
Speaker cord.
Locked
Are the voltages
applied to EAJ1[1][5]pins
of the Audio PWB?
Yes
Are the signals
applied to EAF1[1][3]pins
of the Audio PWB?
Yes
Are there signals
on Speaker Terminals?
Yes
Speaker
28LD5200E (PW1L)
No
AC
inlet
No
[1] +5V P808 [1] +30V
P804
[4] +5V
[8] +6V
[8] +12V
[12] +10V
[1] +12V
P806
applied to P804[3]pin of Power
Unlocked
Check
No sound
Joint / Formatter PWB
No
[1] +5V
[5] +12V
[3] GND
No
[1] L ch
[3] R ch
Formatter PWB or
[2] GND
Video PWB
No
Audio PWB
Power
Power supply
switch
Is the voltage
supply unit high?
No(low)
P804 [3]
Power GO
applied to P804[5]pin of Power
Yes(high)
Are the voltage
applied to EAJ1[1][5]pins?
(When EAJ1 is
disconnected.)
Yes
Audio PWB
20
Sub
Power board
unit
Yes(high)
Is the voltage
supply unit high?
No(low)
P804 [5]
Power OFF
Power
supply unit
No
Power supply
unit