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

[bluto]

Nice. Its sad to think that someone sits there and removes parts until the thing stops working. Then they just put the very last part back and ship it! I didn't notice the lack of a bridge rectifier until you pointed it out. I guess they ran out of them that day! And I just noticed that like yours, the primary filter caps on mine are rated for only 200v. So much for being able to use the high side of the 120v/230v selector switch! They could have left that off and saved another 2 cents. I guess I'll tuck this one away for possible repair in the future just in case.

[370forlife]

The two primary caps are in series, so they can handle 400V total, but only 165uf of capacitance combined. (almost all non-APFC designs use this. APFC designs use a single 400-450V cap to save room for the APFC circuitry.)

[bluto]

That makes sense. I guess even for an el-cheapo PSU, purposely over-volting the primary filter caps would be taking it too far.

[momaka]

Originally Posted by bluto

The large IC (SBL304OPT)- i think is the schottky diode, is showing a short across the two outer pins.

That's normal since the two outer pins connect to the transformer, and SMPS transformers have too few winding on the output side so they always read short circuit between pins.
Instead, try measuring resistance between middle and outside pins. On this one you shouldn't get a short circuit.
Also, you only have 330uF capacitors on the primary, so don't expect more than 200-250 watts from this thing.

[370forlife]

Originally Posted by momaka

That's normal since the two outer pins connect to the transformer, and SMPS transformers have too few winding on the output side so they always read short circuit between pins.
Instead, try measuring resistance between middle and outside pins. On this one you shouldn't get a short circuit.
Also, you only have 330uF capacitors on the primary, so don't expect more than 200-250 watts from this thing.

Yeah I just noticed the "win250" silkscreened on the bottom.

[c_hegge]

Another Excel. It's rated for 400W - ROFLMHO.

[Agent24]

Originally Posted by c_hegge

Another Excel. It's rated for 400W - ROFLMHO.

I've got a 250 Watt Novia which looks exactly the same...

[ratdude747]

Originally Posted by c_hegge

Another Excel. It's rated for 400W - ROFLMHO.

not as bad as the 480 watt echo star with the dummy weights, but still disappointing. the secondary is tiny, ant the primary has 4 diodes. total junk

[japlytic]

The blown Sanyo TT2144 primary transistors were only rated for 250W power supplies: http://www.sacsys.com.tw/marcom/epap...-new/Sanyo.pdf
A possible substitute for the TT2144 is the TT2194 (500VCBo, 400VCEo, 12A, 50W).

[momaka]

Originally Posted by ratdude747

not as bad as the 480 watt echo star with the dummy weights, but still disappointing.

Disappointing indeed, but not that horrible at all. It does have X/Y caps, a coil, and also OVP and UVP. The heatsinks are tiny, though, and there aren't enough caps on the secondary. Note the small transformer marked with a fake size 35 label, too.

Originally Posted by ratdude747

ant the primary has 4 diodes. total junk

That's actually not that much of a problem. Line voltage in Australia is 230v so even if these diodes are rated for 1.5A each, the PSU can still pull 345 watts theoretically (if it can withstand that much ).

[Agent24]

Originally Posted by momaka

That's actually not that much of a problem. Line voltage in Australia is 230v so even if these diodes are rated for 1.5A each, the PSU can still pull 345 watts theoretically.

I agree, what is wrong with using diodes vs a bridge?

Most PSU problems I've seen are stuffed transistors or secondary-side recitifers or leaking capacitors.

Hardly ever see a problem with the primary side components. (unless caused by a fool who flipped the voltage switch or a power surge etc)

[Per Hansson]

Agent24; it is difficult to get airflow down to the diodes
A bridge rectifier is high up so it gets some airflow, plus if the manufacturer wants he can install a heatsink on it aswell

The diode treatment is the cheapo way out, cheaper than using a bridge rectifier...
But it's a more sensible cost savings approach than removing all primary side filtering components like some manufacturers do!

[bluto]

I started messing with this one, harvesting parts from other busted PSUs and such. I have a question about the transformer behind YC1 & YC2. What would one call that piece in order to find a similar unit on Digikey? I pulled on off another PSU, but unfortunately it was a little too big (pins didn't line up with the holes). And what kind of capacitors should I be looking for to populate YC1-YC4?

and that's what the primary side filtering is supposed to look like..

[Agent24]

I think it's a line filter rather than a transformer.

If the holes don't line up exactly you can probably enlarge them or drill new ones. The pads should be large enough to allow for this.

[etnietering]

On Digikey, look under "Common Mode Chokes" in the "Filters" category. There's a couple thousand to choose from.

For the Y capacitors, search for "Y1" or "Y2", and then look in the Ceramic or Film Capacitor categories. Most important thing to worry about here is the lead spacing too.

[bluto]

I am in the ballpark for the coil. I found ones that are somewhat similar looking. But for ~$5, I might look around for some more old PSUs. I guess I can see why they would leave them off to increase the bottom line.
Here is one that I am thinking might work: http://search.digikey.com/scripts/Dk...ame=PLK1324-ND

As for the capacitors there are about 32 different choices that fall under the category 250V/High Voltage/Safety. The pF rating goes from 15pF to 4700pF. Is there any value that I should shoot for here?

[momaka]

Originally Posted by bluto

As for the capacitors there are about 32 different choices that fall under the category 250V/High Voltage/Safety. The pF rating goes from 15pF to 4700pF. Is there any value that I should shoot for here?

Not sure, but from what I noticed most PSUs will use 1nF to 3.3nF (1000pF to 3300pF).

As for the choke - you're probably better off finding some old junk PSUs like you said. They'll likely have the safety X/Y caps too.

[pegdizzler]

Anyone want to see the guts of these?

And maybe a Tagan ITZ 700W (1 of 4 that I'm willing to open, seen in blue box on left side of picture) and a monster DPS-750 (220v) out of an 8-way PIII Xeon server for dessert!

[shovenose]

holy cow uve got lotsa psus

[ratdude747]

only the bad ones, this is not build quality pictorial, this is the hall of shame. server power supplies that are not blown up do not count (they are very nice actually)

in pic #1, i'd try the black one and column 1 2nd from the top. the latter has thin wire (it has to be gutless!) and the black one looks like a gamer wannabe unit...

i see a hipro built one, it has a blue "void if broken" sticker, those are very well built.