Page 1
38
109B2 GS3 CM25
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A. Power Supply Failure
Repair Flow Chart
1. Symptom :
no startup sound
LED light off
2. Symptom :
hicup mode with
startup sound or
blinking LED
check
7157/7155/7113/7154
check 7106 pin1
100V<pin1<380V
NO
check
1101/6102/
7105
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
OPP possibly active
check 3115,3116,
3117,3118,6116,3127
check 7106
Ok
pin4 output ?
check 7106
pin 5 < 0.5V
No
Ok
check
6165/3113/
3114/7105
check
pin6>8V
NO
OK
3. Symptom:
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
Back
Forward
Page 2
B. Video
Repair Flow
1.Symptom :
(with white pattern)
no picture
green LED on
Repair Flow Chart (Continued)
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
check Xray prot.
7503 pin2
check blanking
7503 pin16
No
check blanking
Ok
7503 pin16
Ok
check
VG1 < -150V
check
VG2 > 350V
109B2 GS3 CM25
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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
39
2.Symptom :
no video (or dim),
only raster with/without retrace line
green LED on
check 7301 pin24
2V< ABL < 5V
check 7301
pin11 FLB
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 :
no OSD or
OSD out of sync.
check
7304 pin12
Back
Ok
check 7301
pin 2,3,4 input
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)
Forward
Page 3
40
109B2 GS3 CM25
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C. Horizontal deflection
output repair flow :
Repair Flow Chart (Continued)
1. Symptom :
without
H-deflection.
2. Symptom :
East /West
corr.
3. Symptom :
H-linearity
(full freq. range)
check Hsync
7604 base
enter factory mode
check linearity data
check Hsync
7605 gate
check
7608/7607/
7606
parabola exist
in eeprom
refer cpu
check list
check cpu
pin 4,5,6
check Hsync
7503 pin8
check 7503
pin11
parabola exist
check
3622/3625/
7609 collector
check
7609
check Hsync
7503 pin6
No
refer 7503 check list
or replace 7503
refer 7503
check list
check 7611
pin 5,6,7
replace 7611
Back
4. Symptom :
rotation
5. Symptom :
H_dc shift
6. Sympton :
Focus
check
7626,7627
check
7608,7610
enter OSD
function
disable morier
check 7611
pin 1,2,3
check
7607 collector
7606 emitter
check
7631collector
check
3684/3686
/3681
check cpu
7801 pin2
control range
check
7503 pin 32
check cpu
7801 pin38
control range
check
7624/3655/5609
Forward
Page 4
Repair Flow Chart (Continued)
109B2 GS3 CM25
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41
D. Vertical Deflection Failure
Symptom :
one horizontal line
V_size is abnormal
too large/small (small)
basic check
+13/-13V/+78V
check
7503
pin 12, 13
No
replace
7503
Ok
check
6401
check
+78V,6402,6403
good?
No
replace
6402, 6403
Ok
Ok
check 7404
pin1,pin7 ramp
exist ?
No
check
3401,3402
Back
Forward
Page 5
42
109B2 GS3 CM25
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Repair Flow Chart (Continued)
E. CPU
check list
Basic Check
4. H-linearity
2. H-Centering
19. Blank
14, 13, 12, 11
(Q5,Q4, Q3,
Q2,Q1)
S-cap switch
3. ABL-Adj
check cpu pin 6/pin 5=5V
pin 8/pin 9=12MhZ
check pin 4
pwm from 0V to 5V
check pin2
pwm from 0V to 5V
check pin19
normal : low
change timing : Hi
check Q1-Q5
low:0
hi :1
check pin 3
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
Back
18. Hunlock
27, 20 P.S.
LED
check pin18
normal=Hi
blank=low
check pin20/27
pin27 pin20
normal hi hi
standby hi low
off low hi
Forward
Page 6
22. Degauss
Repair Flow Chart (Continued)
check
active=hi
no active=low
109B2 GS3 CM25
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43
5. Reset
37. Brightness
38. Rotation
23. Keypad
24. Selftest
check
5V
check
pwm from 0V to 5V
check
pwm from 0V to 5V
check key
Enter,+,-,bri,con keys
check pin 24
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 IF cable pin5 - factory mode
5.connect a 5k1 resistor with IF cable pin5 - burn in mode
25, 26. DDC bus
31, 32. IIC bus
check idle status
sda=pin 25=hi
scl=pin 26=hi
check idle status
sda=pin 31=hi
scl=pin 32=hi
check
7804 M24C08
7503 TDA4856
7304 LSC4378P2
7301 TDA4886
Back
Forward
Page 7
44
109B2 GS3 CM25
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Repair Flow Chart (Continued)
F. TDA4841
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 wave
c. pin5 input voltage for the square output waveform
d. pin6 pwm output to 7601 & 7602 base
Vcc=pin9=pin10=12V
gnd =pin7=pin25=0v
pin16
CLBL=hi
pin17 = Hunlock = floating
pin30 = Hpll2 = 0V
pin6 = HDRV = floating
pin8 = BDRV = flaoating
pin12 = Vout1 = floating
pin13 = Vout2 = floating
pin16 = CLBL= Hi
inhibit pin6 output
if pin3 is pulled to
ground by 7508
8. HDRV
11.EWDRV
12,13 Vout1/Vout2
14,15
Vsync,Hsync
to H_deflection.
7605 base
to H_deflection
east/west control
7612 base
differential input
to 7401 pin 1, 7
the input sync from
cpu pin 14,17
16. CLBL
Back
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
Forward
Page 8
Repair Flow Chart (Continued)
109B2 GS3 CM25
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45
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
32. Focus to 7624 for the V dynamic focus
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