Samsung 753x, 76x TROUBLESHOOTING
AN17K*/AN17L* 5-1
5 Troubleshooting
5-1 Parts Level Troubleshooting
Notes: Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit.
• High voltage develops but no raster appears: Video output circuits.
• High voltage does not develop: Horizontal output circuits.
5-1-1 No Power Supply
Chirping noise exists?
Check and replace IC601.
Check and replace D601 and FH1
Done.
No
Yes
Repeating start?
Check and replace D606.
No
Yes
IC601 Pin 1 waveform is right?
Check and replace Q602, IC601,
IC605 and IC602.
Yes
No
C622 Voltage is 13 V ± 0.5V?
Check and replace IC201, IC301,
IC605, IC401, Q402, Q404,
and 12V Regulafor circuit.
Yes
Yes
No
Normal operation?
Replace Main board.
Verify voltages.
No
WAVEFORMS
1
1
100 V (IC601, #1)
CH1 P-P = 100 V CH1 RMS = 350.2 V
CONFIDENTIAL
5 Troubleshooting
5-2 AN17K*/AN17L*
5-1-2 DPMS Failure
Make No H/V Sync. (power off mode)
Check signal source
H/V Sync. video level.
LED blinks?
Check IC201 Pin 40.
Yes
No
+12 V line off?
Check IC201 Pin 5/Pin 6 and
Q610/Q602 operation.
Yes
No
Yes
Q602 Base voltage exists?
Check IC201 Pin 5.
Check and replace Q602 and IC201.
No
IC601 Pin 1 output
voltage exists?
Refer to 5-1-1 No Power Supply.
Done
Yes
No
2
2
100V (IC601, #1)
CH1 P-P = 100V CH1 RMS = 325.8 V
WAVEFORMS
CONFIDENTIAL
5 Troubleshooting
AN17K*/AN17L* 5-3
5-1-3 H_Deflection Failure
Does Horizontal pluse signal
appear at Pin 26 of IC401?
Check IC401.
Yes
No
Does 110 Vp-p signal appear
at Collector of Q403?
Check Q403.
Yes
No
Check Q402, Q404 and T401.
4
Does PWM output signal appear
at Pin 28 (B_DRV) of IC401?
Check IC401.
Check 12 V line.
Yes
No
Does DC 12V appear at
Pin 29 of IC401?
Yes
No
3
5-1-4 S Correction Failure
S1~S3 signals are correct at each
frequency block?
Check S1 ~ S3 signal.
Check and replace Q409, Q410,
Q411, Q414, Q415, Q416, D402,
D403, QD404.
Yes
Check and replace IC201.
No
5
3
2.00 V (IC401, #28)
CH1 P-P = 2.00V CH1 RMS = 5.868V
4
2.00V (IC401, #26)
CH1 P-P = 2.00V CH1 RMS = 5.868V
5
20.0 V (Q403, Collector)
CH1 P-P = 20.0 V CH1 RMS = 46.80V
WAVEFORMS
CONFIDENTIAL
5 Troubleshooting
5-4 AN17K*/AN17L*
5-1-5 H_Lin. Failure Check and Replace T402
5-1-6 Invariable H_Size
IC401 Pin 28 voltage varies with
different B_DRV DAC values?
Q402 Gate output duty varies with
different B_DRV DAC values?
Check some parts around Q402,
IC401 Pin 14 ~ 16.
Yes
No
Check and replace IC401.
No
5-1-7 Abnormal H_Size
IC401 Pin 24 output duty
varies with different B+ offset
DAC values?
Q404 Collector
waveform is right?
Check and replace Q405,
Q406, Q407, and Q408.
Check Components
around D409 and L401.
Yes
Yes
No
Check and replace IC201.
No
6
6
200 V (Q404, Collector)
CH1 P-P = 200V CH1 RMS = 387.2V
WAVEFORMS
CONFIDENTIAL
5 Troubleshooting
AN17K*/AN17L* 5-5
5-1-8 Side Pin or Trap Failure
IC401 Pin 24 output exists?
Yes
Check and replace IC401.
Refer to 5-1-7
Abnormal H_Size
.
5-1-9 Para. or Pin Balance Failure
IC401 Pin 24 output varies with
different DAC values?
No
Replace IC401.
No
7
5-1-10 Tilt Failure
IC201 Pin 20 output duty varies
with different DAC values?
Q611 Base output varies with
different DAC values?
Check and replace Q611.
Check and replace Q301 and Q302.
Yes
Yes
No
Check and replace IC201.
No
Check tilt connector connection
Refer to 5-1-7
Abnormal H_Size
.
Yes
7
1.00 V (IC401, #24)
CH1 P-P = 1.00V CH1 RMS = 3.008 V
WAVEFORMS
CONFIDENTIAL
5 Troubleshooting
5-6 AN17K*/AN17L*
5-1-11 V Deflection Failure
13V and –13V lines are on?
IC401 Pin 23 output exists?
Check and replace IC401.
Yes
Yes
No
Refer to 5-1-1 No Power Supply
No
IC301 Pin 6 output exists?
Check and replace
components around IC301.
Yes
No
Check DY connector connection.
8
9
5-1-12 V Size or Position Variation Failure
IC401 Pin 23 output varies with
different DAC values?
Yes
Check and replace IC201 and IC401.
Check and replace IC301.
No
8
500 V (IC401, #23)
CH1 P-P = 500 V CH1 RMS = 1.425 V
9
10.0 V (IC301, #6)
CH1 P-P = 10.0 V CH1 RMS = 5.06 V
WAVEFORMS
CONFIDENTIAL
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