Troubleshooting - JVC AV-21MT16/Z Service Manual

5.1 SELF CHECK FUNCTIONS
5.1.1 OUTLINE
This model has self check functions given below. When an abnormality has been detected, the SUB POWER is turned off and POWER
LED flashes to inform of the failure. An abnormality is detected by the signal input state of the control line connected to the
microcomputer.
5.1.2 SELF CHECK ITEMS
Check item
B1 over-current protection
CRT neck broken protection
5.1.3 SELF CHECK INDICATING FUNCTION
When an abnormality has been detected at about 5 seconds
after the power was turned on, the SUB POWER is turned off
immediately and the POWER LED flashes.
[ INDICATION BY THE POWER LED]
B1 over-current protection / CRT neck broken protection
SECTION 5

TROUBLESHOOTING

Details of detection
An over-current on the low B1
line is detected.
Operation of CRT neck
protection circuit.
Item
Method of detection
The main microcomputer
detects the possible abnormality
at 24-msec. intervals and judges
the results in every 16 time. Of
the 16 times, if NG is detected
more than 9 times, it is judged
that there is an abnormality.
After about
5 seconds
Start of
Power on
detection
Port
LED flashing intervals
0.3 seconds
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
control unit is not operational
until the power cord
disconnected and connected
again.
Detection of
an abnormality
Flashing LED
SUB-POWER OFF
(No.YA405)1-41
is