Panasonic CT-34WX50 Service Manual ▷ View online
- 3 -
Safety Precautions
General Guidelines
1.
It is advisable to insert an isolation transformer in the AC
power line before servicing a hot chassis.
power line before servicing a hot chassis.
2.
When servicing, observe the original lead dress, espe-
cially the lead dress in the high voltage circuits. If a
short circuit is found, replace all parts which have been
overheated or damaged by the short circuit.
cially the lead dress in the high voltage circuits. If a
short circuit is found, replace all parts which have been
overheated or damaged by the short circuit.
3.
After servicing, see to it that all the protective devices
such as insulation barriers, insulation papers, shields,
and isolation R-C combinations, are properly installed.
such as insulation barriers, insulation papers, shields,
and isolation R-C combinations, are properly installed.
4.
Before switching the power on, measure the resistance
between B+ line and cold side chassis ground. Connect
the “-” side of an ohmmeter to the B+ line, and the “+”
side to chassis ground. Each line must have more resis-
tance value than the specified one as follows:
between B+ line and cold side chassis ground. Connect
the “-” side of an ohmmeter to the B+ line, and the “+”
side to chassis ground. Each line must have more resis-
tance value than the specified one as follows:
5.
When the set is not used for a long period of time,
unplug the AC power cord plug from the AC line outlet.
unplug the AC power cord plug from the AC line outlet.
6.
High voltage points, as high as 33 ± 1.0 kV, are present
when the set is in operation. Operating the set without
the rear cover involves in a dangerous electrical shock
from the set power supply. Servicing must not be
attempted by anyone who is not thoroughly familiar with
the necessary precautions when working on high volt-
age equipment. Always discharge the anode of the pic-
ture tube to chassis ground before handling the picture
tube.
when the set is in operation. Operating the set without
the rear cover involves in a dangerous electrical shock
from the set power supply. Servicing must not be
attempted by anyone who is not thoroughly familiar with
the necessary precautions when working on high volt-
age equipment. Always discharge the anode of the pic-
ture tube to chassis ground before handling the picture
tube.
7.
After servicing, make the following leakage current
checks to prevent the customer from dangerous electri-
cal shock.
checks to prevent the customer from dangerous electri-
cal shock.
Leakage Current Cold Check
1.
Unplug the AC power cord and short between the two
prongs of the AC plug with a jumper wire.
prongs of the AC plug with a jumper wire.
2.
Set the power switch of this set to ON position.
3.
Measure the resistance value with an ohmmeter
between the shorted AC plug and each exposed metallic
part of the set cabinet such as screwheads, connectors,
and control shafts. When the exposed metallic part has
a return path to the chassis, the reading should be more
than 1 M
between the shorted AC plug and each exposed metallic
part of the set cabinet such as screwheads, connectors,
and control shafts. When the exposed metallic part has
a return path to the chassis, the reading should be more
than 1 M
.
When the exposed metal part does not have a return
path to the chassis, the reading must be infinity.
path to the chassis, the reading must be infinity.
Leakage Current Hot Check (See Fig.1)
1.
Plug the AC power cord directly into the AC line outlet.
Do not use an isolation transformer for this check.
Do not use an isolation transformer for this check.
2.
Connect a 1.5k
, 10W resistor, in parallel with a 0.15µF
capacitor between each exposed metallic part of the set
and an earth ground such as a water pipe.
and an earth ground such as a water pipe.
3.
Use a high impedance AC voltage meter to measure the
voltage across the resistor.
voltage across the resistor.
4.
Measure the voltage at each exposed metallic part.
5.
Reverse the AC plug inserting direction at the AC line
outlet and repeat each of the above measurements.
outlet and repeat each of the above measurements.
6.
The voltage at any point must be less than 0.75Vrms.
7.
A leakage current tester (Symptom Model 229 or the
equivalent) may be used to make the hot checks. In this
case, the current must be less than 500µA.
equivalent) may be used to make the hot checks. In this
case, the current must be less than 500µA.
8.
If the reading is more than the above value, the set must
be repaired and rechecked before it is returned to the
customer because of a possibility of an electrical shock.
be repaired and rechecked before it is returned to the
customer because of a possibility of an electrical shock.
X-Radiation
Warning:
1.
The potential sources of X-Radiation in the monitor set
are the high voltage section and picture tube.
are the high voltage section and picture tube.
2.
When using a picture tube test jig for service, make sure
that jig is capable of handling 32.5kV without causing X-
Radiation.
that jig is capable of handling 32.5kV without causing X-
Radiation.
3.
For continued X-radiation protection, in case that at least
one of the components listed below is replaced, follow
the adjustment procedure of the high voltage circuit.
Precise adjustment is necessary for R720 to protect X-
Radiation. Refer to “High Voltage and X-Radiation Pro-
tective Circuit Adjustment section”.
one of the components listed below is replaced, follow
the adjustment procedure of the high voltage circuit.
Precise adjustment is necessary for R720 to protect X-
Radiation. Refer to “High Voltage and X-Radiation Pro-
tective Circuit Adjustment section”.
T551, IC457, IC5508, D512, R520, R521, R522, R809,
R810, R5568, C481, C528, RL001
R810, R5568, C481, C528, RL001
B+ line
Minimum Resistance
220V(TPD7)
10k
144V(TPD17)
10k
23V(TPD25,33)
3k
15V(TPD20)
5k
12V(TPD23)
50k
Hot-Check Circuit
Fig. 1
AC Voltmeter
To
Instrument’s
Exposed
Metallic Parts
Instrument’s
Exposed
Metallic Parts
1.5k
, 10W
0.15
µ
F
Water Pipe
( Earth )
( Earth )
- 4 -
HOLD DOWN OR SAFETY CIRCUIT
INFORMATION
INFORMATION
To monitor the high voltage, the positive DC voltage from the
cathode D512 is applied through R788 and other resistors to
pin 3 of IC475, which is the input terminal of the X-ray Pro-
tection Circuit. The voltage at pin 2 of IC457 is adjusted by
R720 at 5.83 +0.01, -0.02 voltage. Under normal conditions
this voltage is insufficient to activate the X-ray Protection Cir-
cuit.
cathode D512 is applied through R788 and other resistors to
pin 3 of IC475, which is the input terminal of the X-ray Pro-
tection Circuit. The voltage at pin 2 of IC457 is adjusted by
R720 at 5.83 +0.01, -0.02 voltage. Under normal conditions
this voltage is insufficient to activate the X-ray Protection Cir-
cuit.
If the voltage at pin 3 of IC457 increases over the voltage at
pin 2 of IC457 increases and causes the X-ray Protection to
activate. Then it causes the shut down works.
pin 2 of IC457 increases and causes the X-ray Protection to
activate. Then it causes the shut down works.
In the process described above, the voltage at pin 3 of IC457
is compared with the voltage at pin 2 of IC457.
if excessive beam current is drawn, the voltage at oin 3 of
IC457 increases. When the voltage at pin 3 of IC457 over the
voltage at pin 2 of IC457, the voltage at pin 1 of IC457
becomes “high” and feeds into Base of Q401, and the volt-
age at Corrector of Q401 becomes “high” and feeds into pin
38 of micro-controller IC5508 through R5618.
The micro-controller then turns off Q802, causes the AC
power relay RL001 to unlatch and turns off the receiver.
is compared with the voltage at pin 2 of IC457.
if excessive beam current is drawn, the voltage at oin 3 of
IC457 increases. When the voltage at pin 3 of IC457 over the
voltage at pin 2 of IC457, the voltage at pin 1 of IC457
becomes “high” and feeds into Base of Q401, and the volt-
age at Corrector of Q401 becomes “high” and feeds into pin
38 of micro-controller IC5508 through R5618.
The micro-controller then turns off Q802, causes the AC
power relay RL001 to unlatch and turns off the receiver.
Service Instruction: Procedure to apply
silicone to the seal control R720
silicone to the seal control R720
Purpose
To prevent any adjustment on the sealed control after final
adjustment is done at factory. If the sealant are removed
for any reason, the control is damaged at same time.
adjustment is done at factory. If the sealant are removed
for any reason, the control is damaged at same time.
Material
1. Silicone-Type T8C1710201H, manufactured by Shin-Etsu
Chemical Co., Ltd. (Japan)
2. Hard ABS tube-Type TMMX004
Tools
No tool is required.
Procedures
1. Place the hard ABS tube on the designated sealed con-
trol,
trol,
as shown in Figure a.
Figure a.
2. When the tube is gently pressed all the way down and
adhere to the P.C.B., apply the silicon into the hard ABS
tube and form hemisphere like object on the top of tube, a
tube and form hemisphere like object on the top of tube, a
shown in Figure b.
Figure b.
6
1
+
-
X-Ray Detect
38
7
1
2
3
12V
R809
Q802
R810
R5568
IC5508
R5618
R770
C481
R773
R720
R522
R788
R521
D512
FBT T551
R520
C528
R721
12V
EHT
CRT
IC457
AC POWER RELAY
RL001
Comparator Ref.
Comparator out
Comparator in
Silicone
- 5 -
Self-check Function
When symptoms like "the power fails sometimes" or "sometimes there is no picture and/or sound" can not be confirmed at the
time of servicing, the self-check function can be used to confirm the occurrence and to find the defective circuit.
In case of "power failure", flashing of the "VIDEO IN" indication (red) at the front of the unit can be used to narrow down the +B
line.
time of servicing, the self-check function can be used to confirm the occurrence and to find the defective circuit.
In case of "power failure", flashing of the "VIDEO IN" indication (red) at the front of the unit can be used to narrow down the +B
line.
Self-check of the microcomputer control system (bus line)
Indication method
Screen display
<Indication method>
Press the SLEEP button on the
other model TV remote control
simultaneously with the
"VOLUME -" button on the unit.
(The display will be switched to
the screen of VIDEO 1 and the
screen shown on the right will be
displayed.)
Press the SLEEP button on the
other model TV remote control
simultaneously with the
"VOLUME -" button on the unit.
(The display will be switched to
the screen of VIDEO 1 and the
screen shown on the right will be
displayed.)
<Return to the normal screen>
Return to the normal screen will
be made by POWER or any other
remote control operation.
Return to the normal screen will
be made by POWER or any other
remote control operation.
Note:
This model’s remote controller
don’t have sleep Button.
This model’s remote controller
don’t have sleep Button.
[VOLUME-] Button
Display Contents
Indication
No.
Symptom, status
Treatment method
Applicable Board,
applicable Module
H10
No receive for Main picture.
Exchange TNR001.
A-Board
H13
No receive for Sub picture.
Exchange TNR003.
H14
BEE and LED does not work.
Exchange IC5002.
H21
No sound.
Exchange IC2401.
H90
Picture and Sound can not be adjusted.
Exchange IC5001.
H93
No sound.
Exchange IC5003.
H30
TV/AV switching is not possible.
Module exchange
H-Module
H33
No video from component (color differnce) input.
H39
H31
Vector Detector does not operate.
Module exchange
DG-Module
H32
Sub picture is No color (W/B).
H36
Main picture is No color (W/B).
H45
The split screen function does not operation.
H94
Picture is not stationary.
H34
Abnormal sparpness.
Module exchange
AG-Module
H37
VM does not work.
H38
No video, defective OSD.
H51
Horizontal and vertical synchronization not stationary.
Module exchange
Q-Module
hyperOne
DG
IC1310
IC4504
IC4506
IC4513
IC4514
OK H94
OK H36
OK H45
OK H32
OK H31
Primary IIC
AG
IC2503
IC2504
IC2505
OK H34
OK H37
OK H38
Secondary IIC
A
IC2401 OK H21
Q
IC452
OK H51
A
IC5001
IC5002
IC5003
TNR001
TNR003
OK H90
OK H14
OK H93
OK H10
OK H13
H
IC3007
IC3012
IC3013
OK H33
OK H39
OK H30
Check result of IC
"OK" Normal
"NG" Abnormal
"OK" Normal
"NG" Abnormal
(Check IC or its nearby components)
- 6 -
Self check for the power supply
Flashing timing table
When an abnormality has occurred for a power supply line, the protection circuit (power supply protector/detection of abnormal
high voltage) operate and cuts the power supply. At this time, the defective line can be identified by the number of flashes (red) of
the "Power supply/function standby/video reception" indication at the front of the unit by means of the fault line which has oper-
ated the protection circuit.
high voltage) operate and cuts the power supply. At this time, the defective line can be identified by the number of flashes (red) of
the "Power supply/function standby/video reception" indication at the front of the unit by means of the fault line which has oper-
ated the protection circuit.
Flashing
Flashing timing
Contents
Once
Twice
Three times
Four times
Five times
Six times
Seven times
Once
3 sec
No Light
Light
High voltage protect
+25V, +144V overcurrent
detection, vertical drive
+15V voltage drop
detection, vertical drive
+15V voltage drop
DD module main voltage
drop
drop
DD module sub voltage
rise
rise
Voltage drop
(+3.3V/9V/+12V)
(+3.3V/9V/+12V)
+25V, +144 V overcurrent
detection
detection
+5 V voltage drop