the gutless, bloated, and fried power supply hall of shame

[ben7]

Originally Posted by tleu8472

What uF and voltage ratings should I use to add/replace the secondary filtering caps? It does have resistors instead of coils - will this suffice for what will probably be a 250W max load system?

Make sure to use good brand name caps.

This is what I suggest:

3.3v----3300uf 6.3v
12v-----4700uf 16v
5v------3300uf 6.3v
-5v-----470uf 16v
-12v----470uf 16v
5vsb----1000uf 6.3v or 2200uf 6.3v

[Agent24]

Correct ESR is probably more of a concern, with a cheap PSU, capacitors with ESR too low can actually make ripple and noise worse.

I guess you should base that off the original capacitors.

[c_hegge]

Originally Posted by tleu8472

It does have resistors instead of coils - will this suffice for what will probably be a 250W max load system?

Not at all. The resistors do not replace the coils and have absolutely nothing to do with the ripple suppression. They are there to provide a small 'dummy' load for the PSU, since SMPSs need a minimum load in order to start. If you want to improve the ripple suppression, you will need to add the coils. You can scavenge them from dead PSUs.

As for the ratings of the caps to use, ben7 did provide good ratings, but those are total capacitance. so on the 12V, for example, you could use two 2200uF caps. I'm pretty sure that PSU had room for two caps on the 12V rail.

Probably go with Panasonic FC or Nichicon PW series for this PSU.

[ben7]

Also, replace those cheapy "HEC" primary caps, with two 470uf 200v.

[mariushm]

I'd actually say "don't bother" replacing the primary caps on such a cheap poor quality psu. The ones that are now are probably good enough.

Also, probably not really recommended to go up to 3300uF on 3.3v, might be too much for such psu. 2200uF is probably more than enough.

Use 10v rated caps for 3.3v and 5v, from a series with not so low esr, like Panasonic FC, Nichicon PW etc

[Heihachi_73]

King World Enterprises, Proprietary Limidet(?!). No Serviceable Components- Inside. Well, they're right about that at least. The poor tiny transformer even says "YME" on it! In fact, it looks smaller than the one out of the 50W PlayStation 2 I disassembled a while ago. The upside? I have another 80mm fan to add to my collection and a PCB with 18 caps waiting to pop outside on 240V.

This thing struggled to power an office PC consisting of a single 10GB Quantum Fireball HDD, a CD-ROM drive, a floppy and a mainboard which didn't even have an AGP slot (the BIOS chip sits in its place). The only add-on card in fact was a 16-pin 56k modem, which was in its own port, blocking the topmost PCI slot. Everything on this PC was (presumably) factory, right down to the single stick of PC133 SDRAM and 800MHz Celeron. The 3 PCI slots and single ISA slot were seemingly never used, and the fan is almost spotless, no dust at all.

Upon plugging in my trusty old 110W Delta PSU, the board came to life immediately, defaulting to May 26 2001.

When I had found this PC, it had minor water damage, there was rust on the rear ports, and the cables had been cut - ATX/Molex cables, even the cables for the LEDs on the front panel and the CD-ROM audio cable (the HDD/floppy cables weren't touched however). Additionally, someone had obviously thrown it around as the case was missing the front panel and was slightly bent, along with the floppy and CD drive being trashed (the tray was completely ripped out!).

Admittedly, the case itself was made of such thin, flimsy metal that I could cut it with tin snips, it wasn't aluminum though since it was magnetic. I haven't yet tried the hard drive, however the floppy somehow still works after being straightened back out. There are no markings on the board saying what it is, but it is most definitely a variant of this board, the only difference being a 32-pin socketed AMI BIOS being in place of the QFP chip on that page, and the fact that my board has an ISA slot.

The mainboard's caps are a mixture of G-Luxon LZ, SM and SX. Surprisingly, none are bloated unlike the PSU which uses the usual Chinese crap like JEE (primaries), HEC and even Rulycon in this case (the two bloated caps around the 5V rail, and the rest of the black general purpose caps). Also of note, check out the middle "FET" strapped to the heatsink!

The PSU also had one inhabitant, which seemed to be a small redback/widow spider of some sort (however it had no red markings, and the abdomen was only 1/8" or 3mm in size).

[Behemot]

OMG, dual-diode treatment The transformer really seems to be good for 100 W at most.

[Th3_uN1Qu3]

Mmmm Rulycon... They fail without bloating most of the time, they just dry out, so i wouldn't be surprised that those are at fault for the demise of this PSU. Not that it's worth anything other than scavenging for parts.

[Wester547]

I wonder what the schottky's are capable of in that... and if its fan is half-decent... as well as the switching transitor(s)... I'm willing to bet that transformer is fake too..... even the values on the label look underpar for a 250W (and they themselves are obviously lies). IMO. that's more like a 75W PSU (continuously)... I'm also willing to bet that it's less than 60% efficient.

EDIT: In that case, we're looking at a 50-60W continuous PSU... maybe even less...

[Behemot]

The thingy is, 75 W was more than enough for most PIII systems…got here an HP Brio BA410 system with 80 W high-quality PSU inside

[b700029]

...Oh Deer.

If you add up the values on the rails you get 256.2W, so at least they were reasonably close with the addition. The HD30D40PT is a 30A part, presumably serving the 3.3 and 5V rails, I'd say that's within the spec given. I can't read the number on the rearmost diodes but if that's for 12V it looks reasonable for a 10A part, although given the way the diodes-on-a-bracket are mounted maybe they're for 12V...

The transformer is probably good for 100W. I have a 95W laptop AC adapter and its transformer is qutie a bit smaller.

[ben7]

Wow!

Whats up with the burn marks in the second pic?

To me, it looks like two caps are bulging on the secondary, one rulycon and another that I don't know of.

[c_hegge]

That would have made for a pretty good fireworks display

[Wester547]

Originally Posted by b700029

I have a 95W laptop AC adapter and its transformer is qutie a bit smaller.

Are AC adapters honestly capable of doing their rated wattage? They don't even have fans and get even hotter than PSUs do. Not to mention they're obviously much tinier, and it sounds like they have notably smaller transformers... of course, they wouldn't need to do their rated wattage given how little power a notebook draws, but I'm just curious is all. And usually, if you add up every value for every rail on a PSU label, you'll come up with around 50W-100+W more than the "maximum" or "continuous" rating on the label (though I'm sure that's common knowledge here), since not all rails can of course do their labeled rating (lucidly rated at each rail by itself) when combined.

And that "King World" must have a very weak switching transistor.

[mariushm]

Originally Posted by Wester547

Are AC adapters honestly capable of doing their rated wattage? They don't even have fans and get even hotter than PSUs do.

Yes, most brand name ones are. It's only ONE voltage and it's usually 12v or higher, so a low number of Amps.

For example, in the psu discussion thread I posted a HP adapter and its insides and it's a 18.5v @ 3.5A (65w) model - for such voltage/current combo there's no need for a big transformer.

Heat is an issue long term as it can dry out the caps but the temperature usually stabilizes at a certain point so there's no problem with them. Also, the laptops don't really use the maximum the adapters can handle ex this 65w adapter probably averages 35-40 watts throughout the laptop use.

[c_hegge]

Most of the original ones can probably do their ratings, but I don't know about some of the cheap fleabay replacements.

[mariushm]

Originally Posted by c_hegge

Most of the original ones can probably do their ratings, but I don't know about some of the cheap fleabay replacements.

True, as can be seen here: http://electricstuff.co.uk/acadapter.html

[Agent24]

I worry a bit about my Toshiba's power adaptor though. There are no vents, and the thing gets damn hot under full load, in fact they even have a warning label on it about it getting hot.

It's the original part but the OEM is AcBel, so I'm a bit sceptical about what brand capacitors they've used, considering the AcBel from my Power Mac was mostly full of crappy Teapo.

Problem is, it's all welded shut, no screws. I don't really want to cut it open until I can find a way to get it back together again nicely. Duct tape works but looks horrible.

[Wester547]

Originally Posted by mariushm

True, as can be seen here: http://electricstuff.co.uk/acadapter.html

I read that before... scary. I don't think "105C" is the honest thermal limit of a capacitor though... I always thought "105C" and "85C" were the rated limits of how much you can let a capacitor burn in an abuse test (how much ripple it can take) of 2,000 hours or so without going out of spec, which I don't think is the same thing as saying how long it will last under a certain temperature (which if I'm not mistaken is not unveiled due to legal stipulations).

Originally Posted by Agent24

I worry a bit about my Toshiba's power adaptor though. There are no vents, and the thing gets damn hot under full load, in fact they even have a warning label on it about it getting hot.

It's the original part but the OEM is AcBel, so I'm a bit sceptical about what brand capacitors they've used, considering the AcBel from my Power Mac was mostly full of crappy Teapo.

Problem is, it's all welded shut, no screws. I don't really want to cut it open until I can find a way to get it back together again nicely. Duct tape works but looks horrible.

AC adapters will naturally get hot if you run your laptop at full speed (100% CPU speed) as it doesn't help that notebook CPUs get very hot at full load... AC adapters also get much hotter when going through charge cycles as opposed to staying at 100% (when the notebook is on, that is, which is why I recommend only charging your laptop when it's off).

I find it helps to keep the AC adapter on the floor and not on a shelf or something like. And it's likely the AcBel AC adapter has Teapo's as well (not sure if there would be room for much variety capacitor wise in an AC adapter). Though Teapos should do okay as long as they don't get hot in such an operating condition. One of my family's old Toshiba laptops also has a 75W (15V * 5A = 75W, 2.0A input rating) AcBel AC adapter and after 13,000 hours of use and 12,000 power cycles it's still going. Granted, I don't let it get hot, but I'm not sure of its history heat wise. I've also heard that there are little rubber feet that hide the screws on AC adapters, that you can peel off, though I don't know if that's the case with yours.

[c_hegge]

^
Teapos are gonna get pretty toasty in an AC adapter.