Toshiba SD-170EKB2 Service Manual page 6

All output voltages on the power board is 0V or deviated.
Check
there is 300V on C1
Check
oscillating signal on Pin6 of
U1
Check if +5V, , +12V and
-12V are short.
Check whether the components in the
short-circuit voltage are defected or eroded.
All output voltages on
the power board is 0V or
deviated
Yes
Check whether
F1 is blown
No
whether
Yes
whether 100KHz
Yes
Yes
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)