Help with a blow MOSPEC

[dog_at_war]

Hi all, a MOSPEC in my 400W power supply recently failed, it took me 5 hours of testing, unslodering circuits and comparing readings from a 300W PSU with my limited kowledge and experience to figure out it was the 5 volt line and to find the faulty component. the closest match i can find is a mospec from and older 250W AT PSU, Iput it in my 400W one so that i can turn my pc on and get online.

now the one i removed is a S16C40C (16A, 40V) the one i have put in is S15D40C (15A, 40V). i also have available a S10C40C (10A, 40V) and also a SBL1040CT (10A, 40V - I think this is the same as the S10C40C, came out of the 300W PSU)

what i want to know is how does the rating of the original component relate to the power rating of my 5 volt line? it says on the PSU that it can have 40A on the 5V line and 20A on the 3.3V line but not more that 200W combined. I am assuming this mospec is for both the 3.3V and 5V lines. so basically can i leave in the S15D40C as its max rating exeeds 200W (i think, i am not sure exactly how these components work!) and its amost the same as the one that blew, or should i connect the 2 weaker ones in parallel to make one that has a greater rating than the original?

the next question is could something be causing the mospec to fail or do these just blow?

thanks heaps for any help, i have been puzzling over this for hours and hours!

Will

PS: the mospec blew when i was overvolting my cpu

[PeteS in CA]

Re: Help with a blow MOSPEC

It sounds like the failed component is a schottky rectifier, rated as you figured out - 16A, 40V. That sounds a bit wimpy. If the +5V current is rated higher than ~12A, you should look for a 20A or higher rated part. I'd check for a short on the +5V line in the P/S and the MB (e.g. a blown capacitor); be aware that the P/S might have a preload resistor.

[dog_at_war]

Re: Help with a blow MOSPEC

Thanks for your reply! there are no shorts anywhere along the line, the component just failed when i uped the voltages on my memory (2.6->2.8) and cpu (1.65->1.85) to try 220mhz fsb...

I soldered in the 2 10A ones in parallel hoping to make a 20A 40V equivalent (im not sure if that is correnct?) this let me power up with all my things plugged in and seemed to run fine (although at one point, and this was a one-off, i started getting screen corruption/artefacts and restarted, i though this could be related cos i got a radeon 9800xt, uses a bit of power). However after a few hours when i uped my voltages to max to try it all out, after a few minutes of stress testing POP! i lost power and one half of one of the 10A mospecs had shorted. So now i have put the 15A one back in and am running normal voltages and everything seems fine again...

So umm hehe i dont really know what i am doing!! i would really apreciate it if someone could tell me what the go is here? is this mospec the weak point in my PSU?
Should it have a much higher rating than it does to supply anywhere near what the PSU says the line can?
Is it heat related? ths one i have in now althoguh it has a slightly lower rating it has a much bigger surface contact area with heatsink, so will this potentially solve my problem?

oh and would solderign the mospecs in parallel give the rating i though it would?

Sorry for the long posts hehe i apreciate that this may be a lot to explain to someone but id really apreciate it!

cheers,
WIll

PS: although i dont know exactly what i am doing in this case (never seen a mospec), i am a mechanic and have fixed many electronic things before (recapped mobos too) so feel free to be as complicated as need be and ill manage to figure it out

[dog_at_war]

Re: Help with a blow MOSPEC

ack cant edit my previose post hehe, just wanted to add that the 2nd time it blew i only increased the cpu voltage, just seems wierd an increase of only 0.2V to the cpu is causing this component that otherwise seems ok to blow...

[PeteS in CA]

Re: Help with a blow MOSPEC

d_a_w, parallelling two 10A rectifiers like that is not likely to produce the equivalent of a 20A device. I also think it odd that increasing the CPU voltage so little would blow the +5V rectifier like that. I would suggest posting the brand name and model number of the motherboard. I'm not very familiar with that end of things, but many folks here are, and may be able to assist. I wouldn't be surprised to learn that the CPU voltage is derived from the +12V. While you're looking around, look for any leaking or swollen capacitors in the P/S or on the motherboard. Those may be part of the problem or may become an additional problem soon.

[dog_at_war]

Re: Help with a blow MOSPEC

thanks Pete, my mobo is an ASUS A7N8X-X, the PSU is a AGUILER 400W. But now i have gone and done something incredibly stupid and managed to blow something else up, i was adding a heatsink (to the lower one in the pictures) with thermal adhesive cos the one in there looked a little small and got very hot . So all was good till i though "hhmm thats ended up quite close to the live terminal" and grabed the power cord to pull it out and adjust it all and its sliped outta my fingures, bounced back, touched the mains live wire to the heatsink and BANG tripped all my electric off, unfortunatly it has also made my PSU not want to turn on, i have power on the 5VSB and green "on" wire but it just dont want to swith on. i am just wondering what cuircuits might have blown? i have attached some pics of the supply.

i am going to go buy another tomorrow but i still want to fix this one

i have marked with an x and a red line the 2 bits that touched and circled in red the only component thats is connected to the heatsink, i am so pissed at myself for this lol also to the left of that is the rectifier i put in.

so what id like to know is if there is anything in pareticular to check and replace or have i basically screwed lots of stuff up now? i cant find anything burned anywhere, only the wire welded itself to the heasink and the pins the the socket at the back welded a bit too, i can hardly pull the cord outta the back now!

so yeah any help apreciated i really need it lol

Will

EDIT: it looks very hard for the 2 things ive marked to touch hehe but the heasink i glued on top came very close to the marked bit on green board, i took it off so i could look for burned stuff

[japlytic]

Re: Help with a blow MOSPEC

This supply appears to be one made by Deer/L&C... They're not worth repairing.

[dog_at_war]

Re: Help with a blow MOSPEC

i apreciate that japlytic, i have allready ordered a new one online at umart i just want to fix this (or try to) to gain better understanding of how it works and then hopefully be able to applythe knowledge to other stuff (car amps for instance)

sooo i have done some more testing and it apears the 3.3V, 5V and 12V lines are the ones affected, they have been left with all the same resistance to ground of 7.2ohms and they have no resistence between them (wheras in the working supply they do), this leads me to believe that something common to both has fused/fried together.

these are the readings i get for each wire to ground from the blown supply and a working 300W one:

Yellow: 7.2 ----- 260
red: 7.2 ----- 80
orange: 7.2 ----- 11.1
purple: 400 ----- 247
grey: 1k ----- 2.2k
blue: 500 ----- 1k
green: 10k ----- 27k
white: 450 ----- 98

so the only patern i can see there is that yellow, red and orange shouldnt be the same.

so if someone is reasding this and can just point at the pic and tell me whats wrong with this info please feel free

[PeteS in CA]

Re: Help with a blow MOSPEC

The usual color code is that yellow-insulated wires are +12V, red-insulated wires are +5V, and orange-insulated wires are +3.3V. Sounds like some blown rectifiers and/or O/P caps are shorting these three lines together. The reputation of L&C/Deer P/Ss around this forum is that they may be hazardous even for use as paper-weights.

[linuxguru]

Re: Help with a blow MOSPEC

As Pete and Japyltic have pointed, these are one of the Deer/L&C family of supplies - probably an earlier generation. They're usually not worth fixing, except if they're still functional but flaky. That one is definitely not 400W, but more likely close to 150W-200W.

That said, they can still be put to non-critical use - here are the things to look out for:

1. If the +5Vsb is good, but the PSU fails to power on, then it's most probably a bad secondary rectifier - either the one on the +12v rail and/or the +5v rail.

2. Earlier Deers did not have a third rectifier on +3.3v - that was derived from +5v by dropping 1.7v using a MOSFET linear regulator. Check that MOSFET to see if it has a drain/source short. This is mounted on the same secondary heatsink as the two rectifiers.

3. I had posted some upgrades to Deer/L&C supplies in another thread - one of the upgrades is to beef up the secondary rectifiers. For +5v and +3.3v, you can use a SBL2045 or a 3045 (if it physically fits). For +12v, SBL1040 should be OK.

4. Paralleling Schottky rectifiers will not be very effective in doubling their current rating unless they're exactly matched, from the same die. To do this, you have to use a pair from a single package on each leg; that's too messy to mount on a PSU PCB. At any rate, why bother? 20A and 30A-rated Schottky rectifiers cost less than $1 each.

5. Replace all secondary caps with long-life low-ESR non-aqueous caps like the Nichicon PW-series.

[gonzo0815]

Re: Help with a blow MOSPEC

And not forget those small high voltage caps near the SMSPS contorler chip. If those fail, the beaivior could be unexpected and could frying the whole shit out of the conected system.

[kc8adu]

Re: Help with a blow MOSPEC

btw mospec is a brand of semi's
and its very common for those overated deer psu to blow up when run anywhere near their ratings due to inadequate parts.fix it for educational purposes and use it for a rifle target when you are done.

[dog_at_war]

Re: Help with a blow MOSPEC

Thnaks for all your replies! some very helpfull posts here i have had to put the supply on the shelf for a few days becauswe i went and bough a better one on monday (a Skyhawk SH480A8H, dunno how much better but it definatly has much bigger heatsinks) and plugged it in and oh god! my pc wouldnt power on, some quick fiddling revealed that i couldnt power on with either of my hdds plugged in... my damn power supply had grounded through my hdd's!

I was very pissed at this and pulled em out and after a bit of testing managed to figure out it was only the 12v line that had grounded and only through a small diode on the hdd (bottom left of pic), soo i replaced the diodes with some equivalents and my 40Gb Hdd span into life whereas my 80Gb burst into flames! lol must have been somin else wrong.

So i am realy pissed now lol why couldnt it be the other way round? so anyway i took the curcuit board of the 40Gb and fitted it to the 80gb just to see if i could acces all my critical stuff and it worked! the drive makes some horrible clicking and screeching noises but otherwise still runs at full speed and without data corruption, so i managed to recover everything!

but anyway i was hoping that maybe someone has a logic board similar to my fried one from a 80Gb Seagate drive? the fact that my 40Gb board worked on the 80Gb platter leads me to believe they are all very similar and just detect what platter they are connected to (probably/hopefully 99% backwards compatible?) Its not essential as drives r pretty cheap these days and ive recovered all my stuff but if someones got a broken one lying around ill give ya some cash for the board off it just let me know!

so now that my drive problems are pretty much over ill be getting back to trying to fix the PSU hehe. hope someone finds this stuff usefull!

1st pic fixed 40Gb, 2nd burned 80Gb logic board (top left chip) and 3rd is my drive info.

i will let you know how it goes with the PSU hehe

Thnaks again for all the help!

Will

Edit: I uploaded the pics in the wrong order hehe, 1 - 3 - 2

[kc8adu]

Re: Help with a blow MOSPEC

if you got your data back just rma the drive.
seagates have a 5 year warrenty.i use the online rma and am ready to ship it in about 5 minutes.
i also keep the bad ones that are oem for parts to recover data like you just did.never know when you need a headstack or pcb.

[Per Hansson]

Re: Help with a blow MOSPEC

Yea, what kc8adu said...

And also be very happy that you where able to recover the data, I take it since you are looking for the "correct" PCB for it that you want to continue using it longitme, I would not recommend that

Because the firmware contains the list of bad sectors that is specific to that drive only, plus some other misc "individual" stuff...

So congrats on recovering the data but now RMA the drive or retire it, do not trust it with any new data...

[arneson]

Re: Help with a blow MOSPEC

That is a brilliant yet lucky recovery.
If you now have a new PSU you may want to run some diagnostics on that machine.
Power supply short hard enough to hit both drives was a jolt to system.

[gonzo0815]

Re: Help with a blow MOSPEC

wow you are dam lucky to recover your data Big lol.
normaly the pcb hase to fit in any data 100% to be able to get your data and not let the mechanic go apeshit.
But anyhow nice to learn that it could do that way.
hade similar problems with an maxtor, probably same chip. This is quite comon for some series from Maxtor and Seagat. But to high voltages (from inferior psu`s like your L&C) can cause same problem. In any way, as hdd`s are cheap most manufacturer will easily replace that device. And for shure, if you mean "critical stuff" things you under no circumstances want to loose, (anything else than mp3, apps and video) than you shouldN´t even think on using this hdd any further.
Don`t bet that you will have near same luck than you already have had.
And for troubleshooting psu'S, some oldscool systems are pretty fine for that task. If power is to less you can add some resistors or some car lightbulbs.