XV-DV740
96
1
2
4
1
2
3
4
C
D
F
A
B
E
7.1.9 TROUBLE SHOOTING
Microcomputer Section (CONTROL Assy : IC5501)
Symptom
Possible Cause
Check Method
• The unit cannot be turned on.
The microcomputer was not reset.
Check if the level of the terminal XRESET (Pin 8) is "H."
If it is not, check the RESET circuit.
The AC pulse is not input.
Check if the AC pulse is input to Pin 4 of the AC input
terminal. If it is not, check the AC pulse generation circuit.
The oscillation circuit of the microcomputer
does not function.
The microcomputer or the oscillation circuit is broken.
Change the microcomputer or the oscillation circuit.
The unit shuts itself off soon after it is
turned on.
• If the Function is DVD, the voltage of the
VDET input (Pin 17) is either 0.5 Vdd
*
or
less or 0.85 Vdd
*
or more.
• The voltage of the PROTECT input
(Pin 22) is 0.71 Vdd
*
or less.
If the voltage at Pin 17 of the VDET terminal of the
microcomputer is either 0.5 Vdd or less or 0.85 Vdd or
more, adjust so that it stays between 0.5 and 0.85 Vdd.
• DVD does not operate at all.
• Time is not displayed in FL display
during DVD function.
Communication with the DVD
microcomputer has not been established.
• Check that the terminal (Pins 23-25, 29, and 30) for
communication with the DVD microcomputer is live,
and if it is not, check if the flexible cable is
disconnected.
• Check if an "H" signal is output to Pin 93 of the
XDVDRST terminal.
All operation keys are disabled.
The unit recognizes that an operation key
has already been pressed.
If no operation key has been pressed, check if the
voltage at Pins 18 of the KEY input terminal is 5 V. If it is
not, check if the operation switch on the line is in failure.
* Vdd= Approx. 5V (depending on the unit)
ex.) 0.85Vdd= 0.85
×
5 (V)
= 4.25 (V)
www. xiaoyu163. com
QQ 376315150
9
9
2
8
9
4
2
9
8
TEL 13942296513
9
9
2
8
9
4
2
9
8
0
5
1
5
1
3
6
7
3
Q
Q
TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
