Sharp CX51TXZ, Service Manual

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21-1 21-2
CX51TXZ
TROUBLE SHOOTING TABLE TROUBLE SHOOTING TABLE (Continued)
NO RASTER
Blown out.
Replace the fuse.
Check IC701, D701 and
C707.
Abnormal
YES
YES
NO
ON/OFF ON
NO
Abnormal Normal
The fuse is blown out again.
Horizontal circuit oscillate ?
Check Q1005, Q1006,
IC603 and IC801.
D1013 (Power LED Red)
turns on or turns ON/OFF.
Check pin (8) of T701 voltage.
(Approx. 310V at 220V AC)
Check F701.
Normal
Check Secondary Main+B
(Approx. 115V)
Normal
Normal Abnormal Normal
Check CRT connector K1-
K5 bias.
Check
C866 and
L851.
Check
IC801.
Bus error
mode.
See
Fig. 1.
Checking the
protector circuit
(The protector
circuit still works
even if there is no
vertical waveform
at pin (2) of IC1001.)
Check R609 and R611.
D1013 (Power LED Green)
turns on. Check D732, IC702 and
IC704.
Check R701, R707 and
D709.
IC1003
EEPROM (AT24C04)
IC801
V/C/J (TB1226DN)
TU201
PLL (6ED261)
IC401
AV SW (M52797)
IC1801
TEXT (SAA5254)
2s 0.5s
Fig. 1
1) In case of all I 2 C BUS transmission the transmission is continued three times if ACK is not given. If ACK is not
given yet, the process proceeds to the next operation. If ACK is not given when this operation is repeated 10 times,
the mode is changed to BUS ERROR MODE. (If one ACK is given during counting of 3 x 10 times, the counter is cleared.)
2) Upon occurrence of bus error the LED RED (pin 3) blinks as follows, and power-off is performed. At this time the
power key remains valid.
3) If bus error occurs in the SERVICE MODE, V/C/J read-out is inhibited.
Protector operation
1) The protector input (pin 3) is read with 20 ms intervals. If "H" appears successively three times, the mode is changed
to the PROTECTOR MODE. (For 2 s after the POWER port is set to "H", the read-in is set to NOP.)
2) If the H, V, V-GUARD bit of V/C/J STATUS register is "0", the mode is changed to the PROTECTOR MODE.
3) If V-SYNC (pin 2) is not given for 300 ms, the mode is changed to the PROTECTOR MODE. However, this operation
is not performed in the SERVICE MODE and EXTERNAL BUS MODE.
4) If LOW + BIN (pin 27) is not set to "H" for 3s when power is on, the mode is changed to the PROTECTOR MODE.
NO PICTURE, NO SOUND
CIRCUITS TO BE CHECKED:
»
Tuner.
»
PIF.
»
Automatic Gain Control.
»
(5V), (9V) Power Source.
Does the noise level increase at max.
Contrast, Brightness and Sound controls ?
YES
YES
NO
NO
No snow noise.
Does noise or signal appear at pin (26)
of IC401 ?
Noise increases but no signal is
received.
Check the tuner supply voltage MB
must be approx, 9V. BP must approx.
5V. BT must be approx. 31V. And CH
preset data check.
Check the tuner AGC
(TP210).
Does noise or
signal appear at
pin (45) of IC801 ? Check PIF circuits
and its related
parts.
Check IC801.
Check A/V sw
circuits (IC401).
Check Q203, pin
(16) of IC1001 and
include Tuner.
Check Q202,
Q204 and Q205.
YES
(Signal)
NO
YES
(Noise)
Does noise or signal appear
at pin (16) of TU201 ?
NO SOUND
CIRCUITS TO BE CHECKED:
»
Sound system (pins (13) and
(14) of Tuner).
»
Sound Detector Circuit.
»
Sound Switch and Att.
Control.
»
Audio Output Circuit.
YES
NO
YES
NO
Does signal appear at pin
(27) of IC401 ?
Does signal appear at pin
(3) of IC351 ?
Check P302, IC351 and
their peripheral circuit.
Check Tuner.
Check Sound system at pins
(13) and (14) of Tuner.
Check Q201 and its
peripheral circuit.
Check IC401 and its
peripheral circuit.
Normal
Normal Abnormal
5) In the PROTECTOR MODE the next port is forcibly changed. At this time the POWER key is invalid. The test power
is kept turned on. POWER-ON is not performed until resetting is made.
POWER(Pin 37) : "L"
POWER(Pin 15) : "H"
LED GREEN(Pin 4) : "H"
LED RED(Pin 3) : "L"