Samsung AM27A1C07 - Page 9

8
3-2 Fault Diagnosis by Symptom
3-2-1 No Power(completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal?
(2) Is AC power linked correctly?
(3) Are connections between primary side, secondary side of the power transformer
and PCB good.
(4) Is output voltage of DC regulator IC KA7812(IC01) normal? (11.5VDC-12.5VDC)
(5) Is output voltage of DC regulator IC KA7805(IC02) normal? (4.5VDC-5.5VDC)
2) Troubleshooting procedure
Y
N
Y
Y
N
N
N
N
Y
N
Y
Y
Remove power cord and plug in again in approx. 5 seconds.
Is operating lamp lights on for
three minutes, and then goes off?
Check whether the fuse is normal? (F701)
Check whether the output voltage of the trans
is normal? (AC 15V±3V)
Check whether the DC 12V is normal?
(DC12±0.5V between "G" and "O" of the IC01)
Check whether the DC 5V is normal?
(DC 5V±0.5V between "G" and "O" of the IC02)
Check whether the display PCB is normal?
(Check the DC 5V, DC12V, wire, etc.)
Replace the assembly main PCB.
Normal
Replace the fuse (250V, 3.15A)
Replace the trans.
Replace the IC01.
Replace the IC02.
Replace the assembly display PCB
31039A(5)-All 4/17/01 5:36 PM Page 8
Index