Servicing Guidelines - JVC JX-S555 Service Manual

Servicing Guidelines

1. Reference input signals
Video signals
V → Full-field color bar (white 100%), 1.0 Vp-p
Y → 1.0 Vp-p (with sync)
C → Burst level 0.286 Vp-p, chroma only
Audio signal
1 kHz, -10 dBV sine wave
2. YES → Normal
NO → The normal voltage and waveform are not output.
Symptom
1. Power cannot be C903: Across +/- leads
turned ON.
D906: Cathode
D907: Anode
!
Q904: Emitter,
Q905: Emitter,
Q906: Emitter,
"
IC904: Pin 2
2. Display LED CN3: Pins 3 to 7
#
lighting failure.
3. Switch operation CN3: Pins 8 to 14
failure.
$
4. S/V switching IC101: Pins 7, 14, 21 and 28 0 V when S-Video plug is inserted.
failure
%
5. Remote control IC2: Pin 55
&
malfunction
6. The composite Q129: Emitter
video inputs at
CH1 and CH2
are not displayed.
'
Q107: emitter
)
7. The composite Q135: Emitter
video inputs at
CH1 and CH2
are not output at
*
the Monitor
Q115: Emitter
output.
Check Points Normal Voltage/Waveform
Approx. 164 V DC
+9.5 V DC
–9.8 V DC
–6 V DC
+6 V DC
+5 V DC
+9 V DC
0 or +5 V DC
0 or +5 V DC
+5 V when S-Video plug is not
inserted.
+ 5 V DC at remote control
code (See TM.)
Check Results and Failures
NO Check power cord and C901.
If the fuse is blown, check Q901,
T901, D901 and their surroundings.
YES Go to check
NO NO R Check voltage at IC902 and
surroundings.PC901 and IC902
may be defective.
YES Go to check
NO IC901, IC903, IC904 or Q904 to
Q906 defective.
YES Check CN1,. CN3 and wires.
NO IC2 defective.
YES Q701 to Q706 or wire is defective.
NO IC2 defective.
YES CN701, tack switch or wire defective.
NO PJ107 to PJ110 defective.
YES Check IC101 and the surroundings.
NO IC701, CN1, CN702 or wire defective.
YES IC2 defective.
NO Go to check
YES Check IC106, output buffer and their
2.0 Vp-p
surroundings.
NO Check IC101 and surroundings.
YES Check IC103 and their surroundings.
2.0 Vp-p
NO Go to check
YES Check Q152, Q161, Q170 and
2.0 Vp-p
their surroundings.
NO Check IC101 and surroundings.
YES Check IC103 and their surroundings.
2.0 Vp-p
JX-S555(J)
.
!
.
'
.
*
.
(No. 70251) 13