Sharp DV-550U Service Manual page 25

FLOW CHART NO.10 FOCUS TROUBLESHOOTING(2)
Focus servo does not function.
Is the FE waveform at pin(38) of IC707 present?
Yes
Is the output waveform output at pin(43) of IC707?
Yes
Is the focus drive waveform output from pin(17) or
(18) of IC702?
Yes
Is the output waveform applied to pin(2) or (4) of
AB connector from IC702?
Yes
Check the connection of optical pickup cable.
If OK, optical pickup is defective.
FLOW CHART NO.11 LASER TROUBLESHOOTING
The LASER fails light up.
Is "H" level applied at pin(51) of IC303?
Yes
Is applied to the emitter of Q301?
Yes
Is applied to the collector of Q303?
Yes
Is 2.3V applied to the collector of Q307?
Yes
Is 3.3V and 2.3V applied to the pins(11) and (9) of
AB connector?
Yes
Check the AB connector.
If OK, optical pickup is defective.
Tray is not opened.
Does it vary at IC504 (pin 94) when the
tray open-/closing button is pressed?
Yes
Is any signal input from IC504 (pins 70
and 69) to IC701 (pins 2 and 4)?
Yes
Is loading motor drive voltage output
from IC701 (pins 9 and 7)?
Yes
Is loading motor drive voltage output
to AG connector (pins 2 and 3)?
Yes
Visually check the gear and so on of
the mechanical section.
No
No
No
No
No
No
No
No
No
No
Check between IC504 (pin 94) and
tray open-/closing button.
No
Check between IC701 and IC504.
No
Is 8V measured at IC701 (pins 3 and 8)?
Yes
Replace IC701.
No
Check between IC701 and AG connector.
11-3
Check lines between at pin(27) of IC303 and all
the way up thru to pin(38) of IC707.
Check the power circuit line of IC707.
If OK, IC707 is defective.
Is the supply voltage of 8V fed to pin(21) of IC-
702? If OK, IC702 is defective.
Check lines between the AB connector and all
the way up thru to IC702.
The IC303 or IC707 is defective.
Check PC line.
Check a "L" level at base of Q303, Q307.
Replace Q307.
Yes
Is 2.9V applied to the base of Q307?
No
Check between base of Q307 and all the way up
thru to pin(52) of IC303.
Check between Q303 and Q307 and all the way up
thru to AB connector.
No
Check 8V line.
DV-550U