Sharp VT-3448X Service Manual page 56

0
A
Only PB mode inoperative.
Check X7701, C7705
and C7706.
Check the capstan FG
signal line between AC
connector and IC7701.
I
Does PB CTL signal
YES
appear at pin (97) of
NO
Does CTL amplifier
Replace IC7701.
circuit of IC7701 (pins
normally ? (Does the
noise appear at pin (97)
when touch R7774 by
hand ?)
YES
Replace the harness
Is the harness AA-MH
normal ?
I I I
YES
Does the A/C head
Replace NC head.
operate normally ?
CAPSTAN SERVO TROUBLESHOOTING
Capstan servo does not function.
Are REC and/or PI3
mode inoperative ?
YES
Is there 16MHz
NO
oscillation at pins (38)
and (39) of IC7701 ?
YES
Is 2.5V at pin (4) of AC Check R7788, R7793,
pins (90) and (89) of
connector ?
YES
up to the 2.5V line.
Does there appear the
N O
capstan FG signal at pin
YES
YES
Check "@I".
I I
I
Check "@".
GOOD
FLOWCHART NO. 1-12
0
B
Only REC mode inoperative.
I
Does there appear the
V-sync. at pin (84) at
?
T
NO
Check the composite
sync. signal line between
pin (53) of IC2201,
pin (84) of IC7701.
I