[trodas]

( back photo - Image of K3067 busted Enermax 431W - Photobucket - Video and Image Hosting )

So, recently I turned one of my folding machines - a "webserver" one, using Abit KD7-G mobo and powered by Enermax 431W PSU ( Enermax 431W Powersupply Review - PCSTATS.com ) and mid loud explosion happen. Machine did not power on anymore.

The PSU is recapped with quality caps, but I'm affraid that with the Panny TS-ED caps in the input, their ripple is maybe too high and ESR too low, so maybe that is what caused the mosfet pictures above to end how it end. After cleaning I find out that also the 2M ohm resistor to the base of this mosfet is damaged (part of it's leg to the mosfet is gone) and 10A 250V fuse is busted badly - almost like the wire exploded and wallpaper itself on the glass of the fuse

Nevermind. It looks as Fairchild component, very similar (likely) to this Toshiba mosfet: 2SD3067 datasheet pdf datenblatt - Toshiba Semiconductor - N CHANNEL MOS TYPE (HIGH SPEED, HIGH CURRENT SWITCHIGN, CHOPPER REGULATOR, DC-DC CONVERTER AND MOTOR DRIVE APPLICATIONS) ::: ALLDATASHEET :::

Basicaly it is 600V mosfet, 2A current (1mS pulse 5A, 100uS pulse 8A) with RDS(ON) 4.5 ohm and plastic core. Can't find anything on Power Management ICs, Power Semiconductors, Signal Path ICs, Lighting and Display, Logic, Optoelectronics, Fairchild Semiconductor - Global Leader in Power Optimization

So, anyone got idea about available higher grade (mainly lower RDS(ON) and higher current, at least 4A ... ) replacement, guys?

 

[trodas]

I managed to quickly find was a NTE2387 at Mouser, but they asked $13 for it, so... a bit crazy, and it was not TO-220FP - eg. not the isolated one and I cannot have like 250V on the heatsink, that is no-go

K3067 - 600W, 4.5 Ohm RDS(ON), 2A (TO-220FP)
STP3NK60ZFP - 600V, 3.5 Ohm RDS(ON), 2.4A (TO-220FP)
NTE2387 - 800V, 2.7 Ohm RDS(ON), 4A
STP4NK60ZFP - 600V, 2.0 Ohm RDS(ON), 4.0A (TO-220FP)
STP5NK60ZFP - 650V, 1.6 Ohm RDS(ON), 5.0A (TO-220FP)

The best choice is clearly the STP5NK60ZFP, but no stock in Digi or Mouser, but just a slightly worser STP4NK60ZFP is available: Digi-Key - 497-5980-5-ND (STMicroelectronics - STP4NK60ZFP)

So I think I will go with it.

I also have to investigate the cause of failure, because, well, you know. Mosfets did not failing out of the blue, but I was unable yet to find anything besides the gate resistor (2 Megaohms!) damaged (one of it's leg near the mosfet was missing, burned/blasted away) and the fuse blown. And the mosfet cracked.

I beginning to slightly suspect the mosfet failed. The resistor is up to date still 2M (okay, like 1.96 my DMM say) and nothing else is visibly damaged, so, we see when I obtain thru friend or somehow the mosfet.

I probably give it another inspection, just in case I missed something.

I suspect the mosfet failed on the Power On, because I replaced the input caps in the PSU with hi-grade Panny TS-ED caps and they have like twice the ripple the original crap caps had... so maybe there come the source of failure?

We see

 

[Fixz8]

ST Microelectronics:
STP11NM60FP - 600V, 0.4 Ohm RDS(ON), >7.0A (TO-220FP)

Digi-Key - 497-3181-5-ND (STMicroelectronics - STP11NM60FP)

only problem is that the gate charge is about 6x that of the toshiba part. whoops.

 

[trodas]

Yep, total gate charge of this 2SK3067 is only 9nC, witch is pretty low. STP4NK60ZFP got a 18.8nC total, witch should be managable...

2SK3067 - Gate-source = 5nC, Gate-drain = 4nC, Total 9nC
STP4NK60ZFP - Gate-source = 3.8nC, Gate-drain = 9.8nC, Total 18.8nC

Should work fine.