Text preview for : FFH-1920_1950_TROUBLE.pdf part of LG FFH-1920 1950 TROUBLE LG Audio FFH-293AX FFH-1920_1950_TROUBLE.pdf
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TROUBLESHOOTING
Turn power on.
Check power supply circuit.
NO PN508 PIN 8, 6.2V
Is power on? PN508 PIN 7, 5V
IC503 PIN 2, 3.3V
YES
NO NO
Does initial read work? Check the DISK turns Check the connector
PN502, PN503, PN507
YES
YES
Check the Laser
YES
YES
Check the focus circuit
YES
Check the TRAKING circuit
NO
Does it play? Check the tracking servo circuit.
YES
NO
Does it output audio? Check the PN508 PIN1, 3
YES
OK
- 2-2 -
Fails to initial read
NO Check the Voltage change of PN 507 NO Defective connector
Disc motor turns pin2(OPEN, CLOSE) PN507
YES YES
Does RF waveform appear? Check the Data transmission from Defective connector
NO NO
IC501 Pin4 PN507 pin8 to CD DSP PN507 Defective
5V
MICOM
0V
YES
Check the Data transmission from Defective connector
PN507 pin6 to MICOM PN507 Defective
NO
5V
IC501
0V
YES
Check the change of SLDO 2V NO Defective IC501
Voltage(IC501 pin23) 1V
0V
YES
Check the change of SL +, 1.2V NO Defective IC502
YES SL - Voltage 0V
(IC502 pin 18, 19)
0.8V
YES Defective contact PN503
Does laser light? Defective PICK-UP
A
YES
Does FA+ waveform appear at
IC502 pin13?
focus coil drive wareform.
YES
Does TE waveform appear at
IC501 pin 15?
B
TRACKING ERROR wareform
YES
Is rotation normal?
NO
YES
Is there no dropout of RF signal?
Defective IC501
YES Defective PICK-UP
- 2-3 -
A Laser does not light.
Is "3.5V" applied to pin 80 of IC 501?
YES NO
NO NO
Did pickup return to Is data transferred from Defective MICOM.
innermost circular? MICOM IC ?
YES YES
Does voltage appear at IC NO
502 pin 18,19 ? Defective IC 501, 502
YES Defective slide motor and/or
connector.
Does it stop at inner pick Is defect output from LM
circular after shift? SW applied to pin 5 of
YES PN503? NO Defective LMT SW and/or
connector.
OPEN CLOSE
YES Defective MICOM.
YES
NO
Is power supplied to laser Q501? Defective connector.
(Q 501 collector: about 1.8V)
R508