Samsung SyncMaster CKG7507L Service Manual page 28

7 Troubleshooting
7-2 Horizontal Line on CRT or Rainbow Color on the Screen
The first of all you must check
CN301. Does the –12V appear at
Pin 4 of IC301?
Yes
Does the pulse appear at Pin 5
10
of IC301?
Yes
Replace IC301 and check its related
Vertical IC's application.
7-3 Vertical Line on CRT
Does the drive pulse
appear at the emitter of
43
Q401?
Yes
Does the drive output
pulse appear at the Collector
17
of Q403?
Yes
Does the pulse appear at
14
Gate of Q411?
Yes
Check Q411 and D408.
7-2
No
Check the –12V Line at power
secondary part. (D615, C620)
No
Does the sawteeth wave appear
7
at the Pin 9 of IC401?
Yes
Check R303 and R310.
Replace Q403 or check its
No
related circuits.
(C416 and T401)
No
Check IC402 and its application.
No
Replace IC401.
14
CH1 P-P = 15.8 V
17
CH1 P-P = 140 V
43
CH1 P-P = 7.12 V
WAVEFORMS
7 2.80 V (IC401, #9)
CH1 P-P = 2.80 V CH1 RMS = 3.469 V
10 54.8 V (IC301, #5)
CH1 P-P = 54.8 V CH1 RMS = 6.38 V
WAVEFORMS
15.8 V (Q411, Gate)
CH1 RMS = 8.37 V
140 V (Q403, Collector)
CH1 RMS = 52.7 V
7.12 V (Q401, #Emitter)
CH1 RMS = 4.836 V
CKG7507L