I would first check the diodes between the transformer and filter cap.

To prevent causing more problems do service checking with a 100 watt light bulb
in series with the AC line. This bulb normaly should glow bright for a second
when power is applied (Chargine filter caps.) then fade to dim if all is ok.
(no load)
If it continues to be bright with no load on supply you still have problem.
This limits current thru transformer. Saves fuses and transformers or circuit
boards.

good luck,
Don