Service manual

25VT-K100
25VT-CK10
18
FLOW CHART NO.2-4
NO PICTURE, NO SOUND
Check the IC401 and adjacen t parts.
Check the IC401 and adjacent parts.
Check the Q431 and adjacent parts.
Check the CRT connector K1~K5 and adjacent parts.
IC401 pin (22) bias check.
IC501 (TA8403) bias check.
R511, D502, C509, C510
Vertical freq check
CF631 (503kHz)Normal
Abnormal
IC401
Abnormal Abnormal
Normal Normal
NO
FLOW CHART NO.2-3
YES YES YES
YES
YES YES YES
NO
NO
NO
NO SoundNO Picture
NO
NO
NO
NO VERTICAL SCAN
Circuit to be checked: 1. TUNER 2. PIF 3. Automatic gain control 4. 9V power source
Check the IC401 and adjacent parts
Check IC2001.
Check the Tuner AGC.
Check the IC351.
Does the noise level increase at max, Contrast, Brightness, and Sound Control ?
Is there a signal at pin (43) of IC401 ? noise increases but no signal is received Is there a signal at pin (41) of IC401 ?
Picture noise decrease but sound level varies greatly.
Check the tuner bias.
Normal
Abnormal
Abnormal
Check the IC401.
Normal
Check the Tuner circuit.
Abnormal
Check the PC9V line.
Normal
Check the IC401.
Does the 9V (+B) appear at pin (48) of the IC401 ?
Is there a signal at pin (37) of IC401 ?
Is there a signal at pin (53) of IC401 ?
Is there a signal at pin (8) & of IC351 (TDA 7233) ?
Is there a signal at pin (5) of IC351 ?
Check the speaker.
Check the IC401, and adjacent parts.
Is there a signal at pin (54) of IC401 ?