JVC AV21WH3
Service Manual

AV-21WH3 AV-21WS3

AV-21WX3 AV-2178TEE

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 both ECO and ON TIMER LEDs flash 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 Details of detection An over-current on the low B line is detected. Method of detection The main microcomputer detects the possible abnormality at 30msec.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. State of abnormality When an abnormality has been detected, the SUB-POWER is turned off. While the SUBPOWER is being turned off, the POWER key on the remote control unit is not operational until the power cord is taken out and put in again. DITTO

CRT NECK protection

Operation of CRT NECK protection circuit

DITTO

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 LEDs flash.
After about 5 seconds Detection of an abnormality

Power on

Start of detection

Flashing LEDs

SUB-POWER OFF

[ Indication by the LEDs]
Item 1 Over-current protection 2 CRT NECK protection Note: In case of 1 + 2, the item 1 is indicated. LEDs flashing intervals At 0.2-second intervals At 1-second intervals Priority of detection 1 2

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