Samsung DP14LS Service Manual page 33

6 Troubleshooting
6-2-12 High Voltage Failure
Symptoms 1: – No Power
– No Raster
– Unstable operation (Fixed FBT B+ voltage with different H_frequency,
Over 31 kHz: whistle sound, Narrow H_Size, Unsynchronized image, 31 kHz: OK)
Is 53 V on C623?
Yes
Is Q504's drain waveform ok?
13
Yes
Are D502, D503, R509, R510 ok?
Yes
Does B_Out duty of IC401's
Pin 28 vary with different
12
H_frequency and image load
(Full White or No Video)?
Yes
Check and replace Q502, Q503,
IC401, T501.
WAVEFORMS
12 14.0 V (IC401, #28)
CH1 P-P = 14.0 V CH1 RMS = 7.34 V
6-14
No
No
No
No
13 136 V (Q504, Drain)
CH1 P-P = 136 V CH1 RMS = 78.3 V
Refer to 6-2-1 No Power.
Are D515, L501, Q504 ok?
Yes
Are D403, D408, D409, Q402
and Q411, Q412 ok?
Yes
Check and replace AFC input line
from T501 to IC401's Pin 12. :
C408, R406.
Check and replace it.
Check and replace Q502, Q503,
IC401, T501 and REG_IN line to
IC401's Pin 15.
No
Check and replace it.
No
Check and replace it.
DP14L*/DP15L*