Samsung CSH9839, CSH7839, CSH780 Troubleshooting
CSH7839L/CSH9839L 7-1
7 Troubleshooting
7-1 Parts Level Troubleshooting
Notes: 1. If a picture does not appear, fully rotate the brightness and contrast controls clockwise and reinspect.
2. Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit, H/V control circuit, and H/V output circuit.
• High voltage develops but no raster appears: Video output circuits.
• High voltage does not develop: Horizontal output circuits.
7-1-1 No Power Supply
Chirping noise exists?
Check and replace Q659,
IC608 and IC607.
Check and replace FG601, D601.
Done.
No
Yes
Repeating start?
Check and replace Q651, Q602,
ZD601, D615, R606 and D612.
No
Yes
IC601 Pin 1 waveform is right?
Check and replace IC601, IC602,
IC604, D610 and D611.
Yes
No
IC602, IC604, D610 and
D611 are right?
Replace parts and verify voltages.
Yes
No
Normal operation
Replace Main board.
Yes
Verify voltages.
Yes
No
WAVEFORMS
1
1
544 V (IC601, #1)
CH1 P-P = 544 V CH1 RMS = 332.4 V
7 Troubleshooting
7-2 CSH7839L/CSH9839L
7-1-2 DPMS Failure
Make No H/V sync (power off
mode)
Check signal source
H/V sync video level.
LED blinks
Check IC201 Pin 31.
Yes
No
+12 V line off
Check IC201 Pin 1.
Check and replace Q655.
Yes
No
Q654 Base driving voltage exists?
Check IC201 Pin 2.
Check and replace Q654.
Yes
No
Q659 Gate driving
voltage exists?
Refer to 7-1-1 No Power Supply.
Done
Yes
No
WAVEFORMS
2
2
56.4 V (T601, #7)
CH1 P-P = 56.4 V CH1 RMS = 9.18 V
7 Troubleshooting
CSH7839L/CSH9839L 7-3
7-1-3 H_Deflection Failure
IC401 Pin 6 waveform is right?
Q405 source waveform
is right?
Check Q405, R422, R423, R416
and D415, +220 V line.
Yes
Yes
No
1. Check R401, +12 V line.
2. Check IC401 Pins 7~6, 6~5.
3. Replace IC401.
No
Q406 gate, drain
waveforms are right?
Check R426, Q406.
Check +24 V line.
Yes
No
Q407 base, collector
waveforms are right?
Check and replace Q407 and D412.
Check DY connector connection.
No
No
IC251 Pin 4 is high?
Replace IC251.
Check some parts around
Q253 and Q254.
Yes
No
Check some parts around Q252.
IC251 Pin 26 waveform
is right?
Check some parts around IC251.
Yes
No
WAVEFORMS
3
4
5
6
7
9
8
3
3.42 V (IC201, #33)
CH1 P-P = 3.42 V CH1 RMS = 2.500 V
4
3.16 V (IC201, #32)
CH1 P-P = 3.16 V CH1 RMS = 2.560 V
8
230 V (Q405, S
CH1 P-P = 230 V CH1 RMS = 150.1 V
5
12.08 V (Q253, Base)
CH1 P-P = 12.08 V CH1 RMS = 7.396 V
6
2.20 V (IC251, #15)
CH1 P-P = 2.20 V CH1 RMS = 2.776 V
7
10.96 V (IC401, #6)
CH1 P-P = 10.96 V CH1 RMS = 6.180 V
9
29.8 V (T402, #8)
CH1 P-P = 29.8 V CH1 RMS = 7.14 V
7 Troubleshooting
7-4 CSH7839L/CSH9839L
7-1-4 S Correction Failure
S1~S5 signals are right at each
frequency block?
Check S1 ~ S5 signal.
Check and replace Q409~Q413,
C430, C431, C433, C434, C435,
C437 and C441.
Yes
7-1-5 H_Lin. Failure
IC201 Pin 4 voltage varies with
different H_Lin. DAC values?
IC402 Pin 4 voltage varies with
different H_Lin. DAC values?
Check +12 V, –14 V line.
Check some parts around IC402.
Check L402.
Yes
Yes
No
Check and replace IC201.
No
Replace IC201.
No
7-1-6 Invariable H_Size
IC251 Pin 28 voltage varies with
different H_Size DAC values?
IC401 Pin 6 output duty varies with
different H_Size DAC values?
Check some parts around IC401,
IC251 Pin 28.
Yes
No
Check and replace IC251.
No
7 Troubleshooting
CSH7839L/CSH9839L 7-5
7-1-7 Abnormal H_Size
IC201 Pin 5 output duty varies
with different B+ offset DAC
values?
T402 Pin 8 waveform is right?
Check and replace T402.
Check some parts around D407.
Yes
Yes
No
Check and replace IC201.
Check some parts IC201 Pin 5,
IC251 Pin 28 and IC401 Pin 2.
No
7-1-8 Side Pin or Trap Failure
IC251 Pin 24 output exists?
Yes
Check and replace IC251.
Check and replace IC401.
Check some parts IC401 Pin 2
and IC251 Pin 24.
7-1-9 Para. or Pin Balance Failure
IC251 Pin 5 output varies with
different DAC values?
No
Replace IC251.
No
WAVEFORMS
WAVEFORMS
10
11
10
54 V (Q406, Drain)
CH1 P-P = 54 V CH1 RMS = 22.44 V
11
11.6 V (Q406, Gain)
CH1 P-P = 11.6 V CH1 RMS = 6.944 V
7 Troubleshooting
7-6 CSH7839L/CSH9839L
7-1-10 Tilt Failure
IC03 Pin 9 output duty varies
with different DAC values?
IC403 (on Video board)
Pin 3 output varies with different
DAC values?
Check and replace IC402.
Check and replace CRT.
Yes
Yes
No
Check and replace IC03.
No
Check tilt connector connection
7-1-11 V Deflection Failure
±14 V line is on?
IC251 Pin 23 output exists?
Check and replace IC251.
Yes
Yes
No
Refer to 7-1-1 No Power Supply
No
IC301 Pin 1 input exists?
Check CN201.
Yes
No
IC301 Pin 5 output exists?
Check and replace some parts
around IC301.
No
No
Check V DY connector connection.
WAVEFORMS
12
13
12
18.6 V (Q407, Base)
CH1 P-P = 55.2 V CH1 RMS = 9.52 V
13
1.216 kV (Q407, Collector)
CH1 P-P = 1.216 kV CH1 RMS = 316 V
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