Page 1
A. Power Supply Failure
Repair flow chart
104S CM23 GSIII
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39
1. Sympton :
no startup sound
LED light off
2. Sympton :
hicup mode with
startup sound or
blinking LED
replace 7103
check 7103 pin7
100V<pin7<380V
NO
check
1101/6101/
7102/2105
check
7112/7104
/6111
Turn power off
check the resistance for
all output voltages+180,
80,12,-12,+6,+5,+8 V
check 6172/6157/6158
6160/6161 short?
check 7103
Ok
Pin6 output ?
Ok
check
6115/3125/
3126/7102
check
Pin2>2.5V
NO
OK
check 7103
pin 3 normal ?
No
OPP possibly active
check 3125,3116,3117,
3118,6110,6109
OK
3. Sympton:
abnormal sound
check 7156 pin3
voltage dip
check
+8V loading current
check
frequency
F 40KHZ@
No
Check
3131,2110,2111
Ok
check 7156 pin1
No
check
7160/7161
7112/7123
check 7102
drain waveform
right?
Ok
replace 5110
replace 5110
7103 pin7
possibly active by
NoOk
7153 pinC shorted
check CPU pin 10
and 7809 Base
No
Ok
check
6105/3111
2107/2126
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Page 2
40
104S CM23 GSIII
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B.Video
Repair Flow
1.Sympton :
(with wite pattern)
no picture
green LED on
Repair Flow Chart
rough check for R,G, B
1. video input= 0.7V
2. 7099video output waveform
3. 1005 video output waveform
check heater
=+6V
EHT=24.5KV
check Xray prot.
7501 pin2
check
No
check blanking
Ok
7501 pin16
Ok
check
VG1 < -178V
check
VG2 > 350V
check
R,G,B output
No
1005 pin11
1005 pin8
1005 pin6
Ok
check DC restoration
7013,,7033,7053
7014,7034,7054
2.Sympton :
no video (or dim),
only raster with/without retrace line
green LED on
check 7099 pin24
ABL
check 7099
pin11 HFLB
check
7501 pin16
Check 7099
pin5 CLBL
Ok
OkNo
check blanking
7051 pin16
Ok
check Vg1
Vg1=0V
check 7099
pin 6,8,10
input swing
No
replace IF
cable
replace 7099
No turn down Vg2
check 7011,
7031,7051
pin Base
input swing
check cathod
+80V,+180V
check 7012,7032,7052
Pin Collector
Swing
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Page 3
C. Horizontal deflection
output repair flow :
Repair Flow Chart
104S CM23 GSIII
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41
1. Sympton :
without
H-deflection.
2. Sympton :
East /West
corr.
check B+DRV
replace 5612
7623 gate
check 2629,
2610
parabola
exist
check
180V
check B+DRV
7621 base
Ok
6631,6632,3642
check
7610,7611,
7612
parabola exist
check H-Output
7501 pin8
check B+DRV
7623 drain
No
check
check 7501
parabola exist
pin11
Ok
check B+DRV
7501 pin6
No
refer to 7501 check list
or replace 7501
Refer to 7501
check list
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Page 4
42
104S CM23 GSIII
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Repair Flow Chart
D. Vertical Deflection Failure
Sympton :
one horizontal line
V_size is abnormal
too large/small
basic check
+12/-12V
check
3403,3410
Good?
No
Check
7401,3403,3410
Ok
check
2406,2413
check
6401,6403
Good?
No
Replace
7401,6401,6403
Ok
Ok
check 7401
pin2,pin3 ramp
exist ?
Back
No
check
7501
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Page 5
Repair Flow Chart
104S CM23 GSIII
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43
E. CPU
check list
Basic Check
ABL-CON
11,12,13
(Q3,Q2,Q1)
S-cap switch
check cpu pin4=5V
Pin6/pin7=4MhZ
Pin5=gnd
check pin2
pwm from 0V to 5V
check Q1-Q3
Pin13/pin12/pin11
low:0
hi :1
Hor. Freq.(KHz) Q3 Q2 Q1
~27.00 0 0 0
27.50~33.24 0 0 0
33.24~36.51 0 0 1
36.51~42.38 1 1 0
42.38~47.48 1 0 1
47.48~53.10 1 0 1
53.10~58.25 1 1 1
27,28,21,20
Hsync/Vsync
10. Hunlock
14, 17 P.S.
LED
check sync.
Hin=pin27
Vin=pin28
Hout=pin21
Vout=pin20
check pin10
normal=Hi
blank=low
check pin14/17
1. Normal
Fvout=Fvin
Fhout=Fhin
2. sync out of rang
Fhin>54KHz
Fvin>120Hz
pin14 pin17
normal hi hi
standby low hi
off low low
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Page 6
44
104S CM23 GSIII
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24. Degauss
Repair Flow Chart
check
Active=low
no active=hi
3. Reset
19. Keypad
26. Selftest
check
from 5V to 0V
check key
+,-,H-Shift,H-Size,V-Shift,V-Size keys
check pin26
1.no H/V sync & IF cable pin5 floating - show msg.
2.H/V sync exist & IF cable pin5 to ground - normal
3.H/V sync non-exist & IF cable pin5 to gnd - power saving
check
7808/6813/3812
Check
3838~3844
8,9. DDC bus
22,23. IIC bus
15,16. EEPROM
write protection
check idle status
Sda=pin9=hi
Scl=pin8=hi
check idle status
Sda=pin22=hi
Scl=pin23=hi
check pin15 pin16
write : low hi
read : don't care
normal : hi low
check
7806 24W04
7501 TDA4857
7099 TDA4886
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Page 7
Repair Flow Chart
104S CM23 GSIII
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45
F. TDA4857
Check List
1. HFLB
(from H.defl)
2. Xray
(from LOT)
3.4.5.6 B+ control
Basic check
Vcc>9V
during startup
if no exist
if active
a pin3 amplify pin5 and it compare to pin4
b. pin4 generate the saw_tooth waveform
c. pin5 input voltage for the square output waveform
d. pin6 pwm output to 7603 & 7604 base
Vcc=pin9=pin10=12V
gnd =pin7=pin25=0v
pin16
CLBL=hi
pin17 = Hunlock = floating
pin30 = Hpll2 = 0V
Pin8 = HDRV = floating
pin6 = B+DRV = flaoating
pin12 = Vout1 = floating
pin13 = Vout2 = floating
pin16 = CLBL= Hi
inhibit pin6 output
if pin3 is pulled to
ground by 7507
8. HDRV
11.EWDRV
12,13 Vout1/Vout2
14,15
Vsync,Hsync
16. CLBL
to H_deflection.
7605 Gate
to H_deflection
east/west control
7505 emitter
V_differential input
to 7401 pin 2, 3
the input sync from
cpu pin 20,21
Vertical blank will be activated = hi
1.pin30 = softstart pll2 = 0V
2.pin26 = pll1 is unlock in searching mode
3.pin1 = HFLB no exist
4.pin2 = Xray once actived
5.pin10 = Vcc < 9V
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Page 8
46
104S CM23 GSIII
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Repair Flow Chart
17. Hunlock
19. IIC sda = hi
18. IIC scl = hi
21 EHT_compen.
22,23,24
VAGC,VREF ,VCAP
Hunlock pin is floating while pll1(pin26) is
unlock in searching mode
the initial failure may be these
of IC 7501,7099,7801,7806
compensate for the V_size
owing the load variation
pin22 determin the AGC
pin23,pin24 determin frequency
50Hz< freq. <120Hz
26,27,28,29
Hpll1,Hbuf,Href, Hcap
30. PLL2
pin26 determin the
pll1 loop filter
pin 27,28,29 H-Freq
working range
1.compare the HFLB(7501 pin1) and control the phase of H-Output(7501 pin8)
2.softstart
30K<freq.<54KHz
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