computer PSU repair help

Ok, I have a fan that stopped working, and overheated PSU with a fuse that exploded.
When I opened it up I found a cracked F13NK50Z transistor on what seems to be primary side, and managed to take it off somehow.

Now since I'm not an electronic guy, can somebody guide me though this please. I found a datasheet:
https://www.st.com/web/en/resource/technical/document/datasheet/CD00167960.pdf

...and it seems to be this first one:

Type - STF13NK50Z
VDSS - 500 V
maxID - 11 A
Pw - 30 W


Since I cant find this exact transistor in my area what are my options concerning parameters? With which of these three I can go with higher values? Can I get 600V? Or 13 A?


Next there are four transistors on the same heating sink, of which two are J13009, and the fourth is the smallest one hidden behind the coil and almost invisible. Do you reckon any of these work in conjunction with the broken one and that should be repaired?

Yes you can go with higher V, A ratings which should also correspond with lower ON resistance so power dissipation is lower. Of course same geometry case, zener protected, and similar Vgs and input capacitance.

Some of these may be ok.
I am surprised they didn't have a fan fail detect circuit.

Hard to guess on the rest.

Thanx, now I know what to look for.

I'm also surprised it didn't have some sort of protection, it wasn't a cheap one.

Often a failed fan causes the 5V rectifier to go short, you should check this.
If you replace the failed device with a higher current rated device you will need to adjust the output voltages.
You should test the small transistors with a meter.

pjmelect said:

Often a failed fan causes the 5V rectifier to go short, you should check this.

Click to expand...

Sadly, there is almost no way to come near the secondary heatsink diodes
https://oi61.tinypic.com/23s8x9c.jpg

Speaking of protection there seems to be a separate PCB with two (marked on the pic) AS339P-E1 voltage regulators.

If you replace the failed device with a higher current rated device you will need to adjust the output voltages.
You should test the small transistors with a meter.

Click to expand...

Hm... I'm not good with the meter, seems I should get help from a real electronic service.

Ok, thanx for everything.