Samsung SC-148B, Service Manual

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18
Troubleshooting
+5V, +12V of CN701 is normally inputted
after connection of power cable?
X201, X301, X401 oscillate ?
Check power short and power supply cable
connection state
①
IC201 75pin, IC301 12pin, 54pin IC401 87pin for power input
➁
Check C303, C304, C207, C208, R210, C402, C401soldering
➂
If normal replace X201, X301, X401
IC301 19pin change from 0V to 5V ?
Inputted Voltage of IC301 5pin is 1.5V~2.0V ?
Check R401, R402, R333 Rsoldering
Y
Y
N
N
N
N
N
Input / output IC301 57pi n~80pin,
1pin~4pin
pulse waveform ?
Check IC301 pin soldering
Y
Y
Y
N
In case FLASH ROM Memory of IC301 16pin
0V, and Rom memory inputted 5V ?
Check R320, R321 soldering
Check R301, R302 soldering
Equipments required at repair
1. Oscilloscope(100MHz or more ) 2. PROBE for Oscilloscope(10:1)
3. PC(486 ormore)
Verify the circuit of power unit and the first status(Plug-in the power cable without I/F cable and verify.)
A