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7 Troubleshooting
7-2-12 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 56 V on C617?
Yes
Is Q508's drain waveform ok?
13
Yes
Does the PWM duty of IC202's Pin
16 vary with different H_freq.?
Yes
Are D503, D505, D519, R508, R506,
R530, Q203, D216 and D415 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 Q507, Q509,
IC401, T501.
WAVEFORMS
11
CH1 P-P = 5.12 V
CH1 RMS = 4.256 V
7-14
No
No
No
No
No
12
14.0 V (IC401, #28)
CH1 P-P = 14.0 V
CH1 RMS = 7.34 V
Refer to 7-2-1 No Power.
Are Q508, D515, L501 ok?
Yes
Are Q402, D409, D408, D403
11
and Q410 ok?
Yes
Check and replace AFC input line
from T501 to IC401's Pin 12. :
D412, D413, C441, R401.
Check and replace IC202,
Q203, D216.
Check and replace it.
Check and replace IC401, Q507,
Q509, T501 and REG_IN line to
IC401's Pin 15.
13
136 V (Q508, Drain)
CH1 P-P = 136 V
CH1 RMS = 78.3 V
No
Check and replace it.
No
Check and replace it.
CHA42*7L/5**7L
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