Page 1
A. Power Supply Failure
Repair Flow Chart
107P CM25 GSIII
9 Go to cover page
65
1. Sympton :
no startup sound
LED light off
2. Sympton :
hicup mode with
startup sound or
blinking LED
check
7157/7155/7113/7154
check 7106 pin1
100V<pin1<380V
NO
check
1101/6102/
7105/M151
Turn power off
check the resistance for
all output voltages+180,
80,9,13,-13,-6.1,+5,+8 V
check 6148~6159 short?
check 7103
open circuit
Ok
check 7106
pin14 > 2V
NO
check
3121/3122/1106
3124/2121/3136
replace 7106
check 7106
pin 6 < 13.5V
OVP possibly active
No
check 6115
Ok
No
Ok
check 7106
pin 8=2.4V
3131=24kohm
NO
replace 7106
check
3128/6107
/6115
OK
check 7106
pin 5 < 0.5V
OPP possibly active
check 3115,3116,
3117,3118,6116,3127
check 7106
Ok
pin4 output ?
No
Ok
check
6165/3113/
3114/7105
check
pin6>8V
NO
OK
3. Sympton:
abnormal sound
check 7153 pin3
voltage dip
check
+5V loading current
check
frequency
F=72.5KHZ
No
check
3131=24K
Ok
replace 5101
check 7153 pin1
12V< pin1 < 15V
No
check
6162/3170/3171
3173/7157/2165
check 7105
drain waveform
right?
Ok
replace 5101
7106 pin14 OOB
possibly active
NoOk
short 7155 pinC
check CPU pin 22
and 7805 emitter
No
6103/3111/6103/
6108/2128/3112
replace 5101
Ok
check
3Back
Forward4
Page 2
66
107P CM25 GSIII
9 Go to cover page
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. 7301video output =2.5V
3. 7701 video output= 35V swing
check heater
=-6.1V
check
EHT=25KV
No
check Xray prot.
7503 pin2
check blanking
7503 pin16
check blanking
Ok
VG1 < -150V
7503 pin16
Ok
check
check
VG2 > 350V
check
R,G,B output
No
30<2725<80
30<2733<80
30<2753<80
Ok
check DC restoration
7722,7732,7752
7721,7731,7751
2.Sympton :
no video (or dim),
only raster with/without retrace line
green LED on
check 7301 pin24
2V< ABL < 5V
check 7301
pin11 HFLB
check
7503 pin16
check 7301
pin5 CLBL
Ok
OkNo
Ok
check Vg1
Vg1=0V
check 7301
pin 6,8,10
input swing
No
replace IF
cable
replace 7301
No turn down Vg2
check 7701
pin8,9,11
input swing
Ok
replace 7701
check cathod
+80V/+180V
check 7701
pin 1,3, 5
output swing
3. Sympton :
3Back
no OSD or
OSD out of sync.
check
7304 pin12
pin 2,3,4 input
Ok
check 7301
Ok
check
7301 pin1
No
replace 7301
No
check
7304 pin10
VFLB
check 7304
pin2 VCO
pin3 RP
check 7304
pin5 HFLB
No
replace 7304
Ok
check 7304
pin 7,8(IIC)
Forward4
Page 3
C. Horizontal deflection
output repair flow :
Repair Flow Chart
107P CM25 GSIII
9 Go to cover page
67
1. Sympton :
without
H-deflection.
2. Sympton :
East /West
corr.
check Hsync
replace 5613
7604 base
check 2614
parabola
exist
check
180V
check Hsync
7605 base
Ok
6412,7627,7628
check
7608/7607/
7606
parabola exist
check Hsync
check Hsync
7621 drain
No
check
check 7503
parabola exist
7503 pin8
Ok
pin11
check Hsync
7503 pin6
No
refer 7503 check list
or replace 7503
refer 7503
check list
3. Sympton :
H-linearity
(full freq. range)
4. Sympton :
rotation
5. Sympton :
H_dc shift
7602,7603
enter factory mode
check linearity data
in eeprom
refer cpu
chece list
check cpu
pin 4,5,6
check
check
7622,7623
check 7601
pin 1,2,3
check
7624 collector
7625 emitter
check
3622/3625/
7609 collector
check
7610/7612/
7614
check
3656/3614
/3617
check cpu
7801 pin2
control range
check 7601
pin 5,6,7
replace 5611
check cpu
7801 pin29
control range
3Back
6. Sympton :
Focus
enter OSD
function
disable morier
check
7631collector
check
7503 pin 32
check
3607/5618/5613
Forward4
Page 4
68
107P CM25 GSIII
9 Go to cover page
Repair Flow Chart
D. Vertical Deflection Failure
Sympton :
one horizontal line
V_size is abnormal
too large/small (small)
basic check
+13/-13V/+60V
check
3414,3428
good
No
replace
3414,3428,7404
Ok
check
3420,3421
check
+60V,6408,6411
good?
No
replace
6408,6411,7404
Ok
Ok
check 704
pin2,pin3 ramp
exist ?
No
check
7503
3Back
Forward4
Page 5
Repair Flow Chart
107P CM25 GSIII
9 Go to cover page
69
E. CPU
check list
Basic Check
1. H-linearity
2. H-Centering
3. Blank
3,4,5,6,8 (Q5,Q4,
Q3,Q2,Q1)
S-cap switch
7. ABL-Adj
check cpu pin11/pin32=5V
pin9/pin10=12MhZ
pin12/pin31=gnd
check pin1
pwm from 0V to 5V
check pin2
pwm from 0V to 5V
check pin3
normal : low
change timing : Hi
check Q1-Q5
pin6/pin5/pin4
low:0
hi :1
check pin7
pwm from 0V to 5V
Fh-khz Q5 Q4 Q3 Q2 Q1
<31.00 0 0 0 0 0
31.00 ~33.00 0 0 0 0 0
33.00~ 36.30 0 1 0 0 0
36.30 ~40.30 0 1 1 0 0
40.30 ~45.00 1 0 0 0 0
45.00 ~50.20 1 0 0 1 1
50.20 ~56.80 1 0 1 1 0
56.80 ~62.00 1 1 0 0 1
62.00 ~66.00 1 1 0 1 1
66.00 ~71.20 1 1 1 0 0
71.20 ~81.00 1 1 1 0 1
81.00 ~88.00 1 1 1 1 0
> 81.00 1 1 1 1 1
3Back
13~17 Hsync/
Vsync
18. Hunlock
20. 70k / 86k
select
22, 24 P.S.
LED
check sync.
hin=pin13
vin=pin16
hout=pin14
vout=pin17
check pin18
normal=Hi
blank=low
check pin20
70khz=low
86khz=hi
check pin22/24
1. Normal
Fvout=Fvin
2. Self test
Fhout=46.875Khz
Fvout=75Hz
3. sync out of rang
Fhin>72.8 ( or 88.8KHz)
Fvin>168Hz
pin22 pin24
normal hi hi
standby hi low
off low hi
Forward4
Page 6
70
107P CM25 GSIII
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23. Degauss
Repair Flow Chart
check
active=hi
no active=low
26, Reset
28. Brightness
29. Rotation
30. VDC shift
33. Keypad
check
from 5V to 0V
check
pwm from 0V to 5V
check
pwm from 0V to 5V
check
pwm from 0V to 5V
check key
Enter,+,-,bri,con keys
check
2814/6808/3827
check 3814,
3851~3855
34. Selftest
36,37. DDC bus
38,39. IIC bus
40,41. EEPROM
write protection
check pin34
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
4.connect a 15k resistor with IFcable pin5 - factory mode
5.connect a 5k1 resistor with IF cable pin5 - burn in mode
check idle status
sda=pin36=hi
scl=pin37=hi
check
check idle status
sda=pin38=hi
scl=pin39=hi
check pin40 pin41
write : low low
read : don't care
normal : hi hi
7804 M24C08
7503 TDA4856
7304 LSC4378P2
7301 TDA4886
3Back
42. USB int
pin42
hi : active
low : no active
Forward4
Page 7
Repair Flow Chart
107P CM25 GSIII
9 Go to cover page
71
F. TDA4856
Check List
1. HFLB
(fro m H.d efl)
2. Xray
(fro m LOT)
3.4.5.6 B+ control
Ba s i c c h e c k
Vc c > 9V
during startup
if no exist
if ac tive
a p in3 am plify p in5 and it c om pa re to pin4
b. pin4 generate the saw_tooth wave
c. pin5 input voltage for the square outp ut waveform
d. pin6 pwm output to 7601 & 7602 base
Vc c= pin9= pin10= 12V
gnd = pin7= pin25= 0v
pin16
CLBL= hi
pin17 = Hunloc k = floating
pin30 = Hpll2 = 0V
pin6 = HDRV = floa ting
pin8 = BDRV = flaoating
pin12 = Vout1 = floating
pin13 = Vout2 = floating
pin16 = CLBL= Hi
inhibit pin6 outp ut
if pin3 is p ulled to
ground b y 7508
8. HDRV
11.EWDRV
12,13 Vout1/Vout2
14,15
Vsyn c ,Hsyn c
to H_deflec tion.
7605 ba se
to H_deflec tion
east/west control
7612 ba se
differential input
to 7401 pin 1, 7
the input sync from
cpu pin 14,17
3Back
16. CLBL
Vertical blank will be activated = hi
1 .p in 30 = so f tst a rt p ll 2 = 0 V
2.pin26 = pll1 is unlock in searching m ode
3.pin1 = HFLB no exist
4.pin2 = Xra y once ac tived
5.pin10 = Vc c < 9V
Forward4
Page 8
72
107P CM25 GSIII
9 Go to cover page
Repair Flow Chart
17. Hunlock
18. IIC sda = hi
19 IIC scl = hi
20 asymmetry EW
output
21 EHT_compen.
Hunlock pin is floating while pll1(pin26) is
unlock in searching mode
initial fail could be these of IC
7503,7301,7304,7804
to 7503 pin30
for soft start
compensate for the V_size
owing the load variation
22,23,24
VAGC,VREF,VCAP
26,27,28,29
Hpll1,Hbuf,Href, Hcap
30. PLL2
pin22 determin the AGC
pin23,pin24 determin frequency
pin26 determin the
pll1 loop filter
pin 27,28,29 H-Freq
working range
1.compare the HFLBand control the phase of HDRV
2.softstart
compensate for the H_size owing the load variation31 EHT_compen.
30K<freq.<92KHz
50Hz< freq. <160Hz
3Back
32. Focus to 7631 for the V dynamic focus
Forward4
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