HT-CT780
30
3. The sound is not outputted
The voltage of the following is 3.3 V.
MAIN board: IC503 pin 18 (CLIP)
After entering to the tone test mode (Refer
to 2-9. Tone test mode on the SECTION 3
TEST MODE on page 24), test signal is
outputted.
The sound is not outputted.
No
Yes
Check and repair the signal path for
being inputted to the DSP (IC308) on
the MAIN board.
(DSP (IC308) and digital power amplifier
(IC503) on the MAIN board is OK)
Yes
Check and repair the signal path from
the input in turn.
Yes
No
The voltage of the following is 3.3 V
in the state of “VOL 0”.
MAIN board: IC102 pin 57 (AMP_OVF1)
No
Replace the IC503 on the MAIN board.
4. Power is not turned on
Power is not turned on.
The voltage of the following is 28 V.
POWER board: CN902 pin 6 to 8
The voltage of the following is 12 to
18 V.
POWER board: CN902 pin 2
The voltage of the following is 3.3 V.
MAIN board: IC102 pin 46
Yes
POWER board is damaged.
Yes
Yes
Vibrator (X101) on the MAIN board
is oscillated after AC input.
Yes
Fuse (F901) on the POWER board
conduct the electricity.
No
No
No
Replace the vibrator (X101) on the MAIN
board or complete MAIN board.
The reset signal is inputted to pin
49 of IC102 on the MAIN board
after AC input.
Check and repair the area surrounding
IC106 on the MAIN board.
Yes
Yes
No
Replace the complete MAIN board.
No
Replace the fuse (F901) on the POWER
board.
No
Repair the capacitor (C623), diode
(D105) or IC105 on the MAIN board.
The voltage of the following is 3.3 V.
MAIN board: IC105 pin 1
MAIN board: D105 cathode side
The voltage of the following is 4.1 V.
MAIN board: C623 plus side
