Samsung SC-148B Service Manual page 17

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