JVC AV-48P776/H, Service Manual, Page: 53 / 154

1-52 (No.YA318)
SECTION 5
TROUBLESHOOTING
5.1 SELF CHECK FEATURE
5.1.1 OUTLINE
This unit comes with the "SELF CHECK" feature, which checks
the operational state of the circuit and displays/saves it during
failure.Diagnosis is performed when power is turned on, and
information input to the main microcomputer is monitored at all
time.Diagnosis is displayed in 2 ways via screen display and LED
flashes. Failure detection is based on input state of I
2
C bus and
the various control lines connected to the main microcomputer.
5.1.2 HOW TO ENTER THE SELF CHECK MODE
Before entering the SELF CHECK mode, confirm that the setting
of TV / CATV SW of the REMOTE CONTROL UNIT is at the "TV"
side and the setting of VCR / DVD SW is at the "VCR" side. If the
switches have not been properly set, you cannot enter the SELF
CHECK mode.
(1) Press the [SLEEP TIMER] key and set it to 30 minutes.
(2) Press the [VIDEO STATUS] key and [DISPLAY] key
simultaneously, then enter the TEST MODE.
(3) Press the [4] key (SELF-CHK) .
5.1.3 HOW TO EXIT THE SELF CHECK MODE
To Save Failure History:
Turn off the power by unplugging the AC power cord plug when
in the SELF CHECK mode.
To Clear (Reset) Failure History:
Turn off the power by pressing the [POWER] key on the remote
control unit when in the SELF CHECK mode.
5.1.4 FAILURE HISTORY
Failure history can be counted up to 9 times for each item.When
the number exceeds 9, display will remain as 9. Failure history
will be stored in the memory unless it has been deleted.
NOTE:
Only SYNC (with/without sync signals) will be neither counted
nor stored.
5.1.5 POINTS TO NOTE WHEN USING THE SELF CHECK
FEATURE
In addition to circuit failures (abnormal operation), the following
cases may also be iagnosed as "Abnormal" and displayed and
counted as "NG".
(1) Temporary defective transmissions across circuits due to
pulse interruptions
(2) Misalignment in the on/off timing of power for I
2
C bus
(VCC) when turning on/off the main power.
Diagnosis may be impeded if a large number of items are
displayed as "NG". As such, start SELF CHECK only after 3
seconds in the case of receivers and 5 seconds in the case of
panels upon turning on the power. If recurrences are expected,
ensure to clear (reset) the failure history and record the new
diagnosis reults.
Fig.1
Fig.2
1. I2C STOP
2. STATUS DISP.
4. SELF-CHK
5.CONVER OFF
TEST MODE
ROM CORRECTION : ACT
ROM VERSION :
TEST MODE MAIN MENU
Item Item
XRAY XRAY
LOB
LOB
SYNC
SYNC
MEM
MEM
VCD
VCD
AIO
AIO
TUN
TUN
PP
PP
HDMI
HDMI
NG2 NG2
OK
OK
HD:NG
HD:NG
OK
OK
OK OK
OK OK
OK
OK
OCP OCP
TIM
TIM
S:OK
S:OK
AVSW
AVSW
YC YC
IP IP
SPRT
SPRT
NG5 NG5
OK
OK
M:OK
M:OK
OK
OK
OK
OK
OK
OK
OK
OK
NG 4
NG 4
OK
OK
Diagnosis
Normal = OK
Abnormal = NG
<SELF CHECK>