Sharp MD-R3H Service Manual page 64

MD-R3H
• Track search failure
Set the TEST mode, and check whether the slide motor is
started with (skip)
s the following waveform output to the pin 29 of IC750 in track
I
jump state?
Is the following waveform output to the pin 17 of IC750 in track
search mode?
Check the display PWB.
• Triangular wave for focus servo is not output.
Is +5V applied to the pin 36 of IC750?
Is triangular wave observed on the pin 22 of IC750?
Is triangular wave input into the pin 3 of IC700? (Waveform
shown above)
Does saw-toothed wave appear between pins 1 and 2 of
IC700?
Does saw-toothed wave appear between pins 3 and 4 of
CNP751?
PWB pattern breakage
• Sound is not output.
IIs digital signal output from the pin 6 (digital OUT) of CNP301?
Is digital signal sent to the MD PWB and CN1904 pin 4?
Is audio signal output from the pins 24 an 26 of IC201?
(skip).
Yes
Yes
Yes
Yes
1~2 sec.
Yes
Yes
Yes
Saw-toothed waveform
No
Yes
Yes
Yes
OK
Check as stated in item "Slide motor fails to run".
No
IC750 is defective.
No
* The sate where the following waveform is output to the pin 17
of IC750 is referred to as track jump state.
C750 is defective.
I
No
17 PIN
(TSOUT)
+5V line of IC750 is defective.
No
Is the following triangular waveform
No
observed?
Yes
(the wave swings once to +
side.)
Check the periphery of pin 23 of IC750. If it is normal, IC750 is
defective.
Signal line connection failure between pin 22 of IC750 and pin
No
3 of IC700
Check the peripheral parts of IC700 and power line. If they are
No
normal, IC700 is defective.
CNP751 connection failure or optical pickup failure
Yes
Check the pin 28 of IC800.
No
Check Main and MD connection.
No
Check connection of IC1201 and IC201.
No
– 64 –
Kick Pluse
Synchronization is set on
the pin 28 (JPI) of IC750.
TG
This state must be set
after kick pulse is given.
Check the pins 34
and 35 of IC750,
R780 and C769. If
OK, IC750 is
defective. (Check
also the line of pins
No
30, 31, and 33 of
IC901.)