High Voltage Failure - Samsung SyncMaster 1000s Service Manual

7-1-12 V_Size or V_Posi Variation Failure
Does the IC403 Pin 25 output vary
with different DAC values?
Yes
Check some parts around IC301,
+14 V line and -12 V line DC voltage.

7-1-13 High Voltage Failure

Is the DC voltage on Q502
collector 195 V?
Yes
Does the Q501 drain
19
waveform match #19?
Yes
Is the Q502 base
45
waveform correct?
Yes
Does the Q503 drain
21
waveform match #21?
Yes
Done.
SyncMaster 1000s (CGP1607L)
No
Check and replace IC403 and IC301.
No
Check and replace R506, D502 and
Q502.
Check +24 V line.
No
Check and replace Q501, R503, T501
and D501.
No
Check and replace Q502, C504, T502
and CRT.
Check and replace Q503, D503,
No
T503, IC501, IC502, Q504, Q512,
VR501 and C521.
7 Troubleshooting
WAVEFORMS
19 44.4 V (Q501, Drain)
CH1 P-P = 44.4 V CH1 RMS = 26.0 V
21 210 V (Q503, Drain)
CH1 P-P = 210 V CH1 RMS = 109.6 V
45 212 V (Q502, Base)
CH1 P-P = 212 V CH1 RMS = 245.2 V
7-7