JVC AV-21F1P Service Manual page 25

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
X-ray protection
3. Self-check indicating function
When an abnormality has been detected at about 5 seconds
after the power is turned on, the SUB POWER is turned off
immediately and the ON TIMER LED flashes.
[ Indication by the LED ]
Item
Over-current protection/X-ray protection
CRT NECK protection
Details of detection
An over-current on the low B line
is detected.
Also, an over-current for speaker
drive is detected.
Operation of CRT NECK protec-
tion circuit
Operation of X-ray protection cir-
cuit.
LED flashing intervals
At 0.5-second intervals
At 1-second intervals
No. 56033
Method of detection
The microcomputer detects the
possible abnormality at 1-sec.
intervals.
If NG state is detected for more
than 1 ms, the microcomputer
judges that there is an abnormal-
ity.
DITTO
DITTO
After about
5 seconds
Start of
Power on
detection
AV-21F1P
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
DITTO
Detection of
an abnormality
Flashing ON TIMER LED
SUB-POWER OFF
Priority of detection
1
2
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