Samsung CKB7227, CKB5237 Troubleshooting
CKB5237L/7227L 6-1
6 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.
6-1 No Power
Check Fuse, D600, D602, D603
and D604.
Does proper AC 90-264 Volts
appear between the positive and
negative poles of C606?
Yes
No
Check D605, D606, D608, D611,
D614 and T601.
PWM output appear at Pin 1
of IC602?
Yes
No
Check T602 and D614.
Check Power protection.
Check IC602.
AFC Signal appear at negative
pole of C612?
Yes
No
Check D609.
Check IC602.
H-Sync Pulse appear at Pin
5 of IC602?
Yes
No
VCC appear at Pin 3 of IC602?
Yes
No
WAVEFORMS
292 V (T601 #5), 110V
CH1 P-P = 292 V CH1 RMS = 181.6 V
3
3
4
444 V (T601, #5), 220V
CH1 P-P = 444 V CH1 RMS = 354.2 V
3
3.68 V (C612, –), 110V
CH1 P-P = 3.68 V CH1 RMS = 840 mV
4
3.80 V (C612, –), 220V
CH1 P-P = 3.80V CH1 RMS = 902 mV
4
6 Troubleshooting
6-2 CKB5237L/7227L
6-3 Vertical Line on CRT (Root Cause : Horizontal Deflection Parts Fail)
Check 5V,
12V Line.
Check IC302.
Does PWM output signal appear
at Pin 26 (H-out) of IC302?
Yes
No
Does DC 5 V appear at Pin 32
of IC302?
Yes
No
Check Q412 and Q414.
Check Q403.
Does 12Vp-p signal appear at
Emitters of Q412 and Q414?
Yes
No
No
Check CN400, D403 and Q406.
Does 120Vp-p signal appear at
Pin 1 of T401?
Yes
Check swap IC300.
Check connector CN300A.
Check CN300A.
Check DC 13 V Line.
6-2 Horizontal Line on CRT (Root Cause : Vertical Deflection Parts Fail)
Does output pulse of 50Vp-p
appear at Pin 5 of IC301?
Does rectangular signal output
at Pin 5 of IC300?
Yes
No
No
Does DC 13 V appear at Pin 2
of IC300?
Yes
Yes
No
Check DC 12 V Line.
Does DC -12 V appear at Pin 4 of
IC300?
Yes
No
WAVEFORMS
46.0 V (IC300 #5)
CH1 P-P = 46.0 V CH1 RMS = 6.38 V
18
18
6
11
8.80 V (IC302, #26)
CH1 P-P = 8.80 V CH1 RMS = 6.176 V
6
124.8 V (T401, #1)
CH1 P-P = 124.8 V CH1 RMS = 66.16 V
11
WAVEFORMS
6 Troubleshooting
CKB5237L/7227L 6-3
Check Q504, D508 and FBT.
Check Power parts.
Check protection case.
Check Q412 and Q414.
Does secondary voltage appear
at D605, D606, D608, D611 and
D614?
Does DC 5 V appear at Pin 12 of
IC202?
Check IC600
and IC603.
Check IC302.
Does H-out signal appear at Pin
26 of IC302?
6-4 No Raster (1)
Yes
No
Yes
No
Yes
No
Does DC +5 V, DC +12 V appear
at Pins 29, and 32 of IC302?
Yes
No
Does signal appear at base
of Q403?
Yes
No
Check Q403.
Does signal appear at collector
of Q403?
Yes
No
Check Q406.
Does flyback signal appear at
collector of Q406?
Yes
No
Check Q503, Q510, Q512 and Q513.
Does switching pulse appear at
base and collector of Q503?
Yes
No
Check IC501 and FBT.
Does signal appear at gate
of Q504 ?
Yes
No
WAVEFORMS
6
14
22
23
If in a protection case, you must check these case
• Check CN401
• Check Screen VR
• Check VR501
8.80 V (IC302, #26)
CH1 P-P = 8.80 V CH1 RMS = 6.176 V
6
1.016 kV (Q406, Collector)
CH1 P-P = 1.016 kV CH1 RMS = 316.0 V
14
5.28 V (Q503, Base)
CH1 P-P = 5.28 V CH1 RMS = 1.290 V
22
848 V (Q503, Collector)
CH1 P-P = 848 V CH1 RMS = 305.2 V
23
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