Toshiba SD-270EKB2 Service Manual page 6

All output voltages on the power board is 0V or deviated.
All output voltages on
the power board is 0V or
deviated
Yes
Check whether F1 is
blown
No
Check
there is 300V on C1
Yes
Check whether 100KHz
oscillating
Pin6 of U1
Yes
Check if +5V, , +12V and
-12V are short.
Yes
Check whether the components in the
short-circuit voltage are defected or eroded.
whether
signal on
1-3
Yes
Replace F1
No
Replace C1&C2 if D1, D2, D3, D4
are normal.
No
Check/ replace U1.
U1(PIN 3 - RC waveform)
No
Check whether U1 are eroded.
Trouble shooting chart
U1(PIN 8 - Drain waveform)