Troubleshooting (Md Section) - Sharp MD-X7H Service Manual

MD-X8H
When MD fails to operate
If the objective lens of optical pickup is contaminated, MD may fail to operate. At first, clean the objective lens to check playback
operation. If MD fails persistently to operate, perform checks as follows.
If dust or foreign substance is accumulated on the pickup lens, playback is disturbed and indication of TOC (content of tracks) may
be disabled. Before adjusting check that the lens is clean. If the lens is contaminated, treat it as follows.
Turn off power supply, impregnate the lens cleaning paper with a small quantity of isopropyl alcohol, and gently wipe the lens with
it with due care so that the lens is not damaged. At this time do not touch the lens directly with your finger.
Is power turned on in the MD position when the remote
controller or main unit MD STOP button is pressed?
Is disc loading normal?
Is playback state set when the MD PLAY/PAUSE button is
pressed?
Is audio output normal?
Is record and playback operations normal?
• MD power cannot be turned on.
Is normal operation performed when the main unit MD STOP
is pressed?
Is +5V to +6V applied to the pins 15 and 16 of CNS1902?
Is pulse given to the pin 5 of CNS1902?
Is +3.2V applied to the pin 62 of IC1401?
Is 8.4672 MHz pulse applied to the pin 15 of IC1401?
Is pulse output from the pin 34 of IC1401?
Check CNS1902 and system PWB.
TROUBLE SHOOTING (MD SECTION)
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Check as stated in item "MD power cannot be turned on".
No
Check as stated in "Disc Loading is nor normal".
No
Check as stated in item "Playback state cannot be set".
No
Check as stated in item "Audion playback circuit".
No
Check as stated in item "Record playback operations".
No
Check the remote controller, main unit and display PWB.
Yes
Check the power PWB, system PWB and CNS1902.
No
Check the system PWB, CNS1902.
No
Check the periphery of IC1401.
No
Check IC1201.
No
Check IC1401.
No
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