JVC AV-20N8(BK) Service Manual page 26

AV-20N8
SELF-CHECK FUNCTIONS
1. Outline
This model has self-check functions given below. When an abnormality has been detected, the SUB POWER is turned off and the ON
TIMER LED flashes to inform of the failure. An abnormality is detected by the signal input state of the control line connected to the
microcomputer.
2. Self-check items
Check item
Over-current protection
CRT NECK protection
3. Self-check indicating function
At about 3 seconds after the power is turned on, the self-check
function starts.
In the case where an abnormality has been detected within
the subsequent 2 seconds, the ON TIMER LED flashes, but
the SUB-POWER will be turned on when the elapsed time af-
ter power on reaches 5 seconds.
When an abnormality has been detected at about 5 seconds
after power on, the ON TIMER LED flashes, and then the SUB
POWER will be turned off immediately.
[ Indication by the LED ]
Item
Over-current protection
CRT NECK protection
Note: In case of + , the item
26
Details of detection
An over-current on the low B line
is detected.
Operation of CRT NECK protec-
tion circuit
ON TIMER LED flashing intervals
At 0.25-second intervals
At 0.5-second intervals
is indicated.
No. 56030
Method of detection
The main microcomputer detects
the possible abnormality at 30-
msec. intervals and judges the re-
sults in every 16 time. Of the 16
times, if NG is detected more
than 9 times, it is judged that
there is an abnormality.
DITTO
After about
3 seconds
Start of
Power on
detection
Detection of
an
abnormality
State of abnormality
When an abnormality has been
detected, the SUB-POWER is
turned off. While the SUB-
POWER is being turned off, the
POWER key on the remote con-
trol unit is not operational until the
power cord is taken out and put
in again.
DITTO
After about
5 seconds
Flashing LED
SUB-
POWER
OFF
Priority of detection
1
2