Coemar Infinity ACL - moving head stage light PSU issue

[stigwurx]

To whom may read ,
hi . So this light arrived with sparks shooting out of the NTC from both sides , which didn't bode well . The PSU is 200w 20v@0.5A and 40V@4.5A output . Apart from the NTC I found the IRFPC50APBF mosfet and the diode after it both died shorted . Replaced the deceased components but the only sign of life in the PSU was the main bulk capacitor warming slightly.
Replaced the ICE1PCS01G (Power Factor Correction controller) , the UCC3804D ( PWM controller ), the optocoupler and the bulk capacitor . Powered on and the bulk cap promptly proceeded to pop , shooting both magic smoke and sparkles out through the vent in the side.
As I had the parts I went and replaced the BD711 , SPP06N80C3 , all of the smt transistors and the new dead capacitor . Switched on briefly and i could hear the hiss beginning from the replacement cap , switched off and yes she was heading towards warm.
So all rounds have been expended from the parts cannon , the passives on board tested fine. The transformer looks and smells fine, didnt heat up , metered the two secondary windings and the primary but as this in an SMPS transformer I'm in the dark about how to evaluate it .
Now I'm left with assuming the only irreplaceable component is the problem , i.e. the transformer , in which case the PSU is toast and that unit is also no longer available as far as I have found .
So other than some short within the primary winding (which is the conclusion I'm tending towards) are there any other reasons which would cause the cap to blow ? Is there a method to test the transformer off of the board to verify whether it is dead or not ? 
Any suggestions deeply appreciated , I have no schematic to work with so I included a couple of pics of the board instead.

Thanks for reading this far ,
Regards.

[Vicus]

The main bulk cap (only 400v?) can fail is for a sustained inverted voltage (soldered backward?) or for an overvoltage (massive or for a log period). The PFC goal is to raise (with a specialized boost converter) the main rectifier voltage slightly over usual voltage (main voltage RMS * 1.4). The pfc IC have a voltage feedback witch is necessary. If something fail in the loop I suppose the cap could explode for overvoltage. This scenario skerries me but it never happened to me.