Samsung 753x, 76x TROUBLESHOOTING
CONFIDENTIAL
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
Check and replace D601 and FH1
Yes
Chirping noise exists?
No
Yes
No
1
No
No
Normal operation?
Yes
Verify voltages.
Check and replace IC601.
Check and replace D606.
Check and replace Q602, IC601, IC605 and IC602.
Check and replace IC201, IC301, IC605, IC401, Q402, Q404, and 12V Regulafor circuit.
Replace Main board.
WAVEFORMS
1 100 V (IC601, #1)
CH1 P-P = 100 V CH1 RMS = 350.2 V
Done.
AN17K*/AN17L* |
5-1 |
5 Troubleshooting
5-1-2 DPMS Failure
Check signal source
H/V Sync. video level.
Make No H/V Sync. (power off mode)
+12 V line off?
Yes
IC601 Pin 1 output
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voltage exists? |
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Yes
Done
No
Check IC201 Pin 40.
No |
Check IC201 Pin 5/Pin 6 and |
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Q610/Q602 operation. |
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No |
Check IC201 Pin 5. |
Check and replace Q602 and IC201.
No
Refer to 5-1-1 No Power Supply.
CONFIDENTIAL
WAVEFORMS
2 100V (IC601, #1)
CH1 P-P = 100V CH1 RMS = 325.8 V
5-2 |
AN17K*/AN17L* |
5 Troubleshooting
5-1-3 H_Deflection Failure
3 Does PWM output signal appear at Pin 28 (B_DRV) of IC401?
Yes
4
Does Horizontal pluse signal appear at Pin 26 of IC401?
Yes
Does 110 Vp-p signal appear
5
at Collector of Q403?
Yes
Check Q402, Q404 and T401.
No |
Does DC 12V appear at |
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Pin 29 of IC401? |
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Yes |
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Check IC401. |
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No
Check IC401.
No
Check Q403.
5-1-4 S Correction Failure
Check S1 ~ S3 signal.
S1~S3 signals are correct at each |
No |
Check and replace IC201. |
frequency block? |
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Yes
Check and replace Q409, Q410,
Q411, Q414, Q415, Q416, D402,
D403, QD404.
CONFIDENTIAL
No
Check 12 V line.
WAVEFORMS
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
AN17K*/AN17L* |
5-3 |
5 Troubleshooting
5-1-5 H_Lin. Failure 
Check and Replace T402
5-1-6 Invariable H_Size
CONFIDENTIAL
IC401 Pin 28 voltage varies with different B_DRV DAC values?
Yes
Q402 Gate output duty varies with different B_DRV DAC values?
No
Check and replace IC401.
No |
Check some parts around Q402, |
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IC401 Pin 14 ~ 16. |
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5-1-7 Abnormal H_Size
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IC401 Pin 24 output duty |
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No |
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WAVEFORMS |
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varies with different B+ offset |
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Check and replace IC201. |
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DAC values? |
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200 V (Q404, Collector) |
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Yes |
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Q404 Collector |
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No |
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Check and replace Q405, |
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waveform is right? |
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Q406, Q407, and Q408. |
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Yes |
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CH1 P-P = 200V CH1 RMS = 387.2V |
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Check Components |
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around D409 and L401. |
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5-4 |
AN17K*/AN17L* |
5 Troubleshooting
CONFIDENTIAL
5-1-8 Side Pin or Trap Failure
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IC401 Pin 24 output exists? |
No |
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Check and replace IC401. |
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WAVEFORMS
7 1.00 V (IC401, #24)
Yes
Refer to 5-1-7 Abnormal H_Size.
CH1 P-P = 1.00V CH1 RMS = 3.008 V
5-1-9 Para. or Pin Balance Failure
IC401 Pin 24 output varies with |
Yes |
different DAC values? |
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Refer to 5-1-7 Abnormal H_Size.
No
Replace IC401.
5-1-10 Tilt Failure
Check tilt connector connection
IC201 Pin 20 output duty varies with different DAC values?
Yes
Q611 Base output varies with different DAC values?
Yes
Check and replace Q301 and Q302.
No
Check and replace IC201.
No
Check and replace Q611.
AN17K*/AN17L* |
5-5 |
5 Troubleshooting
5-1-11 V Deflection Failure
No
Refer to 5-1-1 No Power Supply
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No |
Check and replace IC401. |
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IC301 Pin 6 output exists? |
No |
Check and replace |
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components around IC301. |
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Yes
Check DY connector connection.
5-1-12 V Size or Position Variation Failure
IC401 Pin 23 output varies with |
No |
Check and replace IC201 and IC401. |
different DAC values? |
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Yes
Check and replace IC301.
CONFIDENTIAL
WAVEFORMS
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
5-6 |
AN17K*/AN17L* |
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