JVC PD-42DX, Service Manual

Page: 46 / 48

PD-42DX
1-46 (No.52088)
SECTION 4
TROUBLE SHOOTING
4.1 SELF-DIAGNOSIS FEATURE
4.1.1 OUTLINE
This model has a "Self-diagnosis function," which checks the operation state of the circuits and informs us of a failure by flashing
POWER LED when a failure occurs.
Diagnosis is performed when power is turned on, and information input to the main microcomputer is monitored at all time.
Failure detection is based on input state of I
2
C bus and the various control lines connected to the main microcomputer.
4.1.2 POINTS TO NOTE WHEN USING THE SELF-DIAGNOSIS FEATURE
POWER LED may flash to inform us of a failure in the following cases, in addition to when circuit failure occurs
(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.
4.1.3 DETAILS
Self-diagnosis is performed for the following items
Type of error
Detection
part
Receiver unit Display unit
Detection timing Unit
Color of
LED
State of
POWER LED
Color of
LED
POWER LED
flash cycle
Low bias
(2.5V / 3.3V / 5V /
9 V) line short
D992
D993
D994
D995
D996
[MAIN PWB]
RED Light RED Flash1.0second
/
Out1.0second
Detection is performed every
150ms.
If nine or more consecutive
errors are detected, the power
is turned off (and turns to
stand-by state). Receiver
Abnormal rise of
temperature in
audio part of
Display unit TH6671
[AUDIO PWB]
RED Flash every 1.0
second RED Flash0.1second
/
Out0.1second
Detection is performed every 1
second.
The power is turned off if the
temperature sensor operates
for 10 seconds or longer. Display
Abnormal power
supply in PDP
(PANEL) (short-
circuit etc.)
PDP
RED Flash every 1.0
second GREEN Flash0.1second
/
Out1.0second
Detection starts 5 seconds
after the power is turned on.
Detection is performed every
16mS.
The power is turned off if NG
continues for 700mS. Display
Abnormal rise of
internal
temperature in
Display unit TH101
[PDP POWER
PWB]
RED Flash every 1.0
second GREEN Flash0.1second
/
Out0.1second
Detection starts 5 seconds
after the power is turned on.
Detection is performed every
16mS.
The power is turned off if NG
continues for 300mS. Display
Abnormal
operation of PDP
(PANEL)
PDP
RED Flash every 1.0
second GREEN Flash1.0second
/
Out1.0second
Detection starts 5 seconds
after the power is turned on.
Detection is performed every
16mS.
The power is turned off if NG
continues for 2000mS. Display
Abnormal rise of
temperature in
power supply part
of Display unit IC505
[PDP POWER
PWB]
RED Flash every 1.0
second GREEN Flash2.0second
s
/
Out2.0seconds
Detection is performed every
0.5 second.
If a temperature rises beyond
the temperature predetermined
for detection of error over the
predetermined permissible
times the power is turned off. Display