Samsung SyncMaster 753DF Service Manual page 24

5 Troubleshooting
5-1-5 H_Lin. Failure
IC201 Pin 21 voltage varies with
different H_Lin. DAC values?
Yes
IC603 Pin 9 voltage varies with
different H_Lin. DAC values?
Yes
Check Q412, Q413, T402.
5-1-6 Invariable H_Size
IC401 Pin 6 voltage varies with
different B_Out DAC values?
Yes
Q402 Gate output duty varies with
different B_Out DAC values?
5-1-7 Abnormal H_Size
IC401 Pin 11 output duty
varies with different B+ offset
DAC values?
Yes
Q404 Collector waveform is
6
right?
Yes
Check some parts around D409, L401.
5-4
No
Replace IC201.
No
Check +13 V, –10 V line.
Check some parts around IC603.
No
Check and replace IC401.
No
Check some parts around Q402,
IC401 Pin 3 ~ 6.
No
Check and replace IC201.
No
Check and replace Q405, Q406, Q407,
Q408.
WAVEFORMS
6 200 V (Q404, Collector)
CH1 P-P = 200V CH1 RMS = 387.2V
SyncMaster 753DF/755DF