either at least one blown transistor or diode.
I would start by testing Q1 if the display you sent me was plugged into it,
it killed Q1 on mine the moment i plugged it in and turned it on so if it is blowing fuses with out the display connected thats where i would start.
or you can test the transistors for shorts with your multimeter set to continuity or diode test, it won't prove that they are ok but if it beeps or shows a very low voltage drop / short on diode test then it will tell you that the transistor is stuffed.
test all the transistors and diodes, if you replace all the shorted ones after doing this test and it still blows fuses then you are going to have to remove all the semiconductors in the hv section and test them one at a time.
you can also try cutting one of the leads on D4 and replacing the fuse, power it up and see if the fuse blows. then resolder the cut lead on D4 and then cut a lead on D3 and try again.
if you look at the schematic you will see which diode does the + side and which does the - side and you should be able to isolate it to either the + or - assuming both sides are not blowing fuses.
As you know there are high voltages in this section so I would be sure to unplug the machine from the wall before doing any work.
