wrote in message
ups.com...

There is this Samsung DVD which blew up due to over voltage in the
mains supply. I have checked all the necessary and almost all
components on the board and they are all in good oder. I even replaced
some of them just to be sure but still it will not switch on. BTW the
Fuse blew and was replaced with the same type and rating. I hear fiiin
sound probably from the transformer and the pilot lamp (LED) does not
come on . What might be Wrong? Please help.


First of all rule out shorts on the primary and secondary sides. Seems as if
you've pretty much done this on the primary side - do check all rectifier
diodes AND ZENER DIODES on the secondary side. Confirm the switcher is
running, and that nothing is loading down any of the power supply lines.
Typical readings might be 3.3 volts, 9 or 14 volts, possibly a negative
voltage matching that. You could have an open resistor. You may very well
need a 'scope, service manual, and an ESR meter for further troubleshooting.


Mark Z.