Troubleshooting - Samsung CF21M Service Manual

5 Troubleshooting

5-1 Parts Level Troubleshooting
Notes: 1. If a picture does not appear, Click the Brightness and Contrast button on the front panel, and then increase the value
of Brightness and Contrast.
2. Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit, H/V control circuit, and H/V output circuit.
• High voltage develops but no raster appears: Video output circuits.
• High voltage does not develop: Horizontal output circuits.
5-1-1 No Power Supply
Check and replace FG601, D601,
D701, Q701, IC601 and ZD601.
Check the Voltage at
C607 plus polarity point.
Is the Voltage 400V
with PFC : 400V
without PFC : it is different
according to input voltage
Yes
IC601 Pin 1 waveform is right?
Yes
The secondary voltage of
T601 is right?
(Is it same the schemetic diagram)
Yes
Check IC651 (KA78R12) Pin 12?
•
Is the voltage 12V
DC
•
Yes
Done.
CF21M*
No
?
DC
DC
No
No
No
?
Check and replace
FG601, D601, D703.
Check and replace
IC601, ZD601, D606, IC701.
Check TR, IC and biode
+
related to every B line.
Appear 4V Pin 4 of IC651?
DC
No
Check and Micom. (IC201)
Check and replace IC651.
•
Check every IC connected to 12V.
•
Yes
5-1