Sharp LC-20B2EA, Service Manual

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13
LC-20B2EA
TROUBLE SHOOTING TABLE
No picture and No sound
Check all the settings microprocessor's adjust process menu.
Do F1 and F2 function?
Are T3701's secondary outputs, +31V, +22V, +9V, +5V and -8V normal?
Remove F1 and F2 and check the load side. Is there short-circuiting?
Is there short-circuiting of T3701 primary side periphery, Q3700, Q3701 and S4701.
Replace F1 and F2.
Check S4701 and connection cable.
Is T3701's primary oscillator waveform normal?
Check T3701's secondary load.
Yes
Yes
No
No
No
No No
Yes
Check J3702 periahery and connection cable.
Replace F6700~F6704.
Is the pin (34) of IC1201 in the "H" state?
Is the output of Q3650 in the "L
" state?
Yes Yes
No No No
Yes Yes
Check the OFL1 line, IC1201 and their peripheral parts.
Check the OFL line, Q3650 and their peripheral parts.
Check T6700~T6709, Q6700~Q6714 and connection cable.
Back light lamp failure to light up
Is the primary side of T6700 ~T6709 periphery short-circuiting?
Replace the back light lamp with new one and check again.