Text preview for : bc989p_troubl.pdf part of LG bc989p troubl LG VCR bc991v bc989p_troubl.pdf



Back to : bc989p_troubl.pdf | Home

ELECTRICAL TROUBLESHOOTING GUIDE
1. Power Circuit(SMPS)
(1) No 5.3VA.


No 5.3VA.


YES

NO Replace the F101
Is the F101 normal?
(Use the same Fuse).

YES

NO
Is the BD101 normal? Replace the BD101.


YES

NO
Is the R101 normal? Replace the R101.


YES

Does the oscillation waveform appear at NO Is Vcc(about 13~15V) permittable at the
the IC101 Pin 1? IC101 Pin 5?

YES NO

Check or Replace the D103.




NO
Is there DC voltage at the IC101 Pin 4? Replace the IC102.

YES

NO
Is there about 2.5V at the IC103 Vref ? Replace the IC103.


YES

NO
Is the D106 normal? Replace the D106.

YES

Check the Main PCB 5.3VA Line short?




3-3
7. Power Circuit(SMPS)
(2) No 12VA.(Capstan)


No 12VA.


YES

NO
Does 5.3VA work normally? Check whether 5.3VA is out of order.

YES

NO
Is the D109 normal? Replace the D109.


YES

Check 12VA Line of the Main PCB short.




(3) No 12VA (CANAL, Buffer)



No 12VA.


YES

Is Vcc(about 14VA) put into the Q155 NO
Replace the Peripheral Circuitry of Q155.
Collector?

YES

Is Voltage(about 14V) put into the Q155 NO 1. Check the ZD151 and the Peripheral
Base? Circuitry.
2. Check the R105.
YES

Check or Replace the Q155.




3-4
7. Power Circuit(SMPS)
(4) No 5VT(5V)


No 5VT.(5V)


YES

Is 5.3VA put into the Q152(Q151)
collector?

YES

NO
Is the Q163(Q162) Base "H"? Check the