Hmmm there is a reason that went bad, probably bad caps even if they look good or bad PSU. Trannies just do not die with age. The STD50N03 is similar but not exact.
MY guess is figure out why it died, fix that and then try to replace it...

Looks same to me as how you read it.
I found datasheets for D50N03L, and some other variants D50N03-whatever, but not A.

This is the only site where I see the "A" version listed. The text on the search result implied they have a datasheet, but I don't see it.
https://www.dzsc.com/ic/sell_search.html?keyword=D50N03A
https://translate.google.com/translate?sl=aut … yword%3DD50N03A

Maybe there's some standard for what the "L" and "A" suffixes mean, but I don't know. Maybe the difference isn't important.
Does anybody else have this board? If so, do you have a different MOSFET part number? Then at least we'd have a known substitute part.

EpoX boards do typically have bad caps, so if you haven't replaced them already then that's another thing to look into.

Yep I agree the board needs a complete shotgun as well as that MOSFET. I pulled the trigger on three of the "L" variants on eBay out of China. So they are on the way.

@shamino what other variants did you find?

Also anyone here who installs capkits I'm in Virginia?

Thanks for your time.

Kicking myself now as i found the "L" variant on DIgi-Key...

https://www.digikey.com/product-detail/en/stm … 70-1-ND/1883384

script-fu wrote on 2020-09-30, 03:11:

Kicking myself now as i found the "L" variant on DIgi-Key...

https://www.digikey.com/product-detail/en/stm … 70-1-ND/1883384

Can't find the brand, but others 'A' variant are fairly easily found online (try limiting the search 50N03A), Here's one specsheet from (Vishay) General Semiconductor

Get these from digikey. Chinese sellers, these semiconductors are fakes. I bought few high freq ampifiers IC from chinese and they were junk.

Cheers,

Others that came up in search results were:
SUD50N03-06P (Vishay)
SUD50N03-09P (Vishay)
These don't have the "L" or the "A", they're just plain D50N03.
I forgot they had that "SU" prefix on them also. It seems like different manufacturers stick different prefixes like that on equivalent parts, so I'm inclined to think it's not important, but I could certainly be wrong about that. No idea what the suffixes mean.

I just noticed a thread on badcaps where somebody found D50N03A on an Epox KP6-BS. I have that board, and it's handy since I was in the middle of boxing things up. Just checked and mine has
CEB6030L (CET brand)
So apparently that's an interchange Epox used. I've seen CEB6030L on lots of motherboards, they must have been cheap in bulk back then.

PC Hoarder Patrol wrote on 2020-09-30, 04:42:

script-fu wrote on 2020-09-30, 03:11:

Kicking myself now as i found the "L" variant on DIgi-Key...

https://www.digikey.com/product-detail/en/stm … 70-1-ND/1883384

Can't find the brand, but others 'A' variant are fairly easily found online (try limiting the search 50N03A), Here's one specsheet from (Vishay) General Semiconductor

GFD50N03A_GeneralSemiconductor.pdf

That's awesome thank you php!

shamino wrote on 2020-09-30, 04:54:

Others that came up in search results were: SUD50N03-06P (Vishay) SUD50N03-09P (Vishay) These don't have the "L" or the "A", the […]
Show full quote

Others that came up in search results were:
SUD50N03-06P (Vishay)
SUD50N03-09P (Vishay)
These don't have the "L" or the "A", they're just plain D50N03.
I forgot they had that "SU" prefix on them also. It seems like different manufacturers stick different prefixes like that on equivalent parts, so I'm inclined to think it's not important, but I could certainly be wrong about that. No idea what the suffixes mean.

I just noticed a thread on badcaps where somebody found D50N03A on an Epox KP6-BS. I have that board, and it's handy since I was in the middle of boxing things up. Just checked and mine has
CEB6030L (CET brand)
So apparently that's an interchange Epox used. I've seen CEB6030L on lots of motherboards, they must have been cheap in bulk back then.

@shamino this thread? https://www.badcaps.net/forum/showthread.php?t=639

That's interesting how you were able to deduce all the info. Then actually have that MB in arms length to confirm cool man! I also think @PC Hoarder Patrol datasheet find falls inline as well spec wise. I will need to put them all in a spread sheet to confirm the specs.

I found this post as well over on BC. https://www.badcaps.net/forum/showthread.php?t=3133

That post is Just another confirmation and more part numbers! Looks like you guys nailed this down quick and i really appreciate all the help!

Also @shamino I found this on your board

https://forums.anandtech.com/threads/anyone-w … e-board.765978/

Which led me to

https://web.archive.org/web/20050205153923/ht … 001/d010614.htm

Yeah, I remember running into that site sometime back. The author really dug into that board. I think it had a bit of an enthusiast following for a while because it was one of the cheapest dual slot-1 440BX boards.

A few years ago I got the KP6-BS on eBay. It was a pretty good lot of "as-is" boards but that one needed work. It had blown caps, a fried inductor, and 2 bad fan headers (the attached transistors were killed by a bad CPU fan). I recapped the board and replaced those other parts but not the MOSFETs.
It seemed to recover nicely. It even handled memtest86 with a 133FSB overclock and dual CPUs installed. My only complaint was that the PCI clock doesn't have a 1/4 setting, so 133FSB won't be very usable unless I find a workaround for that.

The fan transistors seem underspecced. They were marked "610" which I think is NDS0610:
https://www.onsemi.com/pub/Collateral/NDS0610-D.PDF
I expect they probably used the same parts on their other boards at that time.

Unless I've misunderstood the datasheet, it seems like they can only handle up to 0.12A. At least that's what it says for "Continuous Drain Current".
I have conflicting notes about what I used as replacements, but they were rated for something like 1-2A. I have no idea how much can be safely drawn without burning out the board traces though.

Anyway be careful with your fan headers. I think they're a bit easy to burn out.