Troubleshooting (Md Section) - Sharp MD-MX30 Service Manual

MD-MX30/MX30W
MD SECTION
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 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?
• Playback state cannot be set.
Is it impossible to set both high reflection disc and low
reflection disc to playback state?
Yes
Only the high reflection disc cannot be played back.
Yes
Is 1.3V to 1.6V applied to the pin 93 of IC1401 with the high
reflection disc inserted?
Yes
After re adjustment check as stated in item "Normal playback".
• Audio playback circuit
When sound is not output although the playback time display advances during playback in the normal mode.
Is audio output waveform observed on the pins 24 nad 26 of
IC1701?
Yes
Is audio output waveform observed on the pins 26 and 28 of
CN1501?
Yes
Check the main PWB.
Yes
Yes
Yes
No
Check as stated in item "disc Loading is not normal".
No
Check as stated in item "Playback state cannot be set".
No
Check as stated in item "Audio playback circuit".
No
Check as stated in item "Record and playback operations".
No
Check as stated in item "TEST mode check".
No
No
Only the low reflection disc cannot be played back.
Yes
Is 1.6V to 1.9V (record enabled) or 2.0V to 2.3V (record disabled)
applied to the pin 93 of IC1401with the low reflection disc inserted?
Yes
No
Check SW1931loading PWB, and CN1931.
Check the pins 70, 71, 72 and 74 of IC1201, and the pins
12, 16, 17, and 19 of IC1701.
No
Check connection between IC1701 and CN1501.
No
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