Sharp 27DV-S100 Service Manual page 70

The [No Disc] indication. (In case focus servo does not function.)
No
Is the focus control signal output to
the pin(158) of IC701?
Yes
Is the focus control signal from the
No
pin(158) of IC701 input into the pin(23)
of IC7701?
Yes
No
Is the focus control drive voltage output
from the pins(17) and (18) of IC7701?
Yes
Is the focus control drive voltage
No
applied to the terminal of focus
actuator?
Yes
Check the connection of optical pickup
cable. If it is normal, replace the
traverse chassis unit.
The [No Disc] indication. (When the laser beam does not light.)
Is the Q303(LD POWER CTL) drive
No
output to the pin(46) of IC301?
(Checking of symptom.)
Yes
No
Is 5V voltage applied to the emitter
of Q303?
Yes
No
Is approx. 2V applied to the pin(3)
of the pickup terminal? (See note.)
Yes
Check the connection of optical pickup
cable. If it is normal, replace the
traverse chassis unit.
FLOW CHART No.3-3
Check the crystal oscillator at pin(11)
of IC701 and its peripheral circuits.
Check the focus control signal line
between the IC7701 and IC701.
Check PC 8V line.
No
Is 8V voltage applied to the pin(8) of
IC7701?
Yes
Check to see if the signal at pin(21) of
IC7701 is at "H" level. If not, replace
IC7701.
Check the line between the IC7701
and the focus actuator.
FLOW CHART No.3-5
Check the line between the pin(46)
of IC301 and the base of Q303.
Check the A_5V line.
Check the line between the Q301,
Q307 and pickup terminal.
Note: Since the laser diode is very susceptible to static
electricity, be careful of static electricity or electricity
leak from the measuring equipment when confirming
the voltage.
Both picture and sound do not operate normally.(1)
Set the disc on the disc tray.
Yes
No
Do you have loading done the disk by
normality?
Yes
No
Is the level of RF signal which is output
from pins(29), (30) of IC301, normal?
Yes
No
Replace the main PWB unit.
Yes
See FLOW CHART NO.9 and NO.10.
FLOW CHART No.3-4
Check the loading switch.
Check for contamination of objective
lens of optical pickup.
Yes
Replace traverse chassis unit.