Well, carelessness got the better of me, for once! Brand new Seasonic SS300FS. Opened the case, forced power on (paperclip on atx connector, as usual), did a quick 'voltage test' with my meter to see what may be 'live', and ... fan stopped turning. No spark, no smoke, no noise - just that the fan stopped. Now, no voltage anywhere except 110 AC on the input.

I then realized that I had my meter connected wrong ... it has a regular red socket, but it also has a second red socket for 'dc/ac amps only' - and I plugged the red lead into it by mistake - first time in 15 years with this stupid meter!

Anyway - "All I Did" was touch the smaller of two heatsinks when the fan stop occurred .... so I basically shorted the smaller heatsink to ground.

I cannot see any fuse; any burned out resistor/cap/etc.

Does anyone have a suggestion (other than trash can ...)?

By the way; I'm a 'fan' of the Zalman PSU (and I was going to try the nexus this time), but I saw this Seasonic at my local PC store, and remembered it had favorable reviews, so decided to buy it. Comparing to the Zalman, the interior is way poorer - smaller heatsinks, one of which is a cheapo stamped, no on/off, "ADDA" fan, and no fuse .

With this seasonic, I was about to do my usual trick of inserting a resistor in the power lead to the fan (which Mike Chin and I discussed at length in regards to the Zalman) last year http://forums.silentpcreview.com//viewtopic.php?t=2408&highlight=panaflo.

So I guess Nexus it is ... But I'd still like to salvage this guy if possible!

Thanks!

can u rma/return it?

No, because I've already cut out the fan grill!!! (part of my standard routine whenever I buy a PSU). This is another strike against the Seasonic, by the way - it has a stamped fan grill, not a removable wire type.

My only hope is that someone else has blown one and figured out how to repair it!

Thanks!

Leave it alone for a day & then try starting 'er up again . I don't exactly how/why but self-protection shut down in PSUs seems to work like that sometimes. Leave it alone for a while & it resets itself. Good luck.

Well, fixed it! There is a fuse, but it's soldered to the pc board, and completely wrapped in heat-shrink tubing, thus resembling a different component. I finally removed the pc board from the 'case', and examined it with a flashlight, and recognized it.

Sure enough, after slicing off the tubing, saw that the fuse was blown. Rating looked to be 7A (hard to read, and of course, no indication on PC board or in manual!). Soldering a fuse strikes me as yet another cheap move. Luckily, my other two spare PSUs have 'socketed' fuses, so nabbed one from one of them (only 4A, but worked).

After that, was back in business!

By the way - the heatsink I was testing when I blew this thing is at solid -160 V DC. I happened to touch it and the case with my hand, and got a real jolt! This is the first time I've come across this in a PSU (I was testing initially just as a precaution, not expecting anything untoward). I can't really figure out 'how' it has this voltage level. The heatsink only has one device attached to it (transistor-like), and it appears to have a very clear isolation shim of some sort - so where is this voltage coming from?!!

FYI, the voltage to the fan is supplied at 12V, and the regulation is on the other side; the 'negative' lead is at around 6V. I put a 22 ohm resistor in series with the fan and it slowed it down quite nicely.

Any comments on the ADDA fan? label says 'ADDA Brushless AD 08 12HS-A70GL. With no load on the PSU, and a 22 ohm resistor in series, voltage drop across the resistor was 1.7 V, thus it was drawing 77mA. Was pretty quiet but didn't compare to others.

Thanks again!

I just get impressed at those people who is willing to work on PSU without discharging it at least few hours first...
I usually turn my computer off, switch PSU off, replace it with backup PSU,
let the PSU sit 24 hours before I open it up, etc.
Never got shocked by it yet and don't plan to.
(Does life insurance covers you for this stuff BTW?)

I was in a power supply the other day, and I was careful not to touch anything I didnt need to touch, but I did end up touching several different things and never got shocked. I think if your careful then you will probably be okay.

I opened the case of this unit straight out of the box (never powered up), so nothing to discharge. I then cut out the fan grill. Then, stripped off insulation on the wire to the fan and so I could measure it's voltage. THEN, powered it up so I could do some tests.

My very first test was to carefully monitor the heatsinks for voltage; black wire to case, red wire to heatsink. This normally is a very safe, precautious way to see what's 'live'. Sadly, I had the red lead of my meter hooked up as an ammeter (read: short circuit)!!! In this mode, 'anything' I measured would have blown! Can't believe I did that.

I could happily and safely touch the heatsink as long as I was not grounded; but when I put one finger on the heatsink, and another finger on the case, my whole arm lit up! (a first for me in over 30 years messing with electronics!).

But I can't understand why the heatsink would be sitting there at -160V DC. It's not the capacitor, by the way - it's a very clear reading, coming from the heatsink, repeatedly. The heatsink has only one item attached to it.

The other thing I don't understand is the voltages on the fan. I just read Mike Chin's review of the Seasonic
http://www.silentpcreview.com/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=20&page=1

He talks about measuring ~5V on the fan. I measured 12V on the fan; but ... on the negative lead, I measured about 6V, thus about 6V is being applied to the fan. So was Mike simply referring to the net voltage across the fan, or was the regulation really on the + side on his model? My Zalman PSU regulates the + side, and I measure 5, 6, 7 etc Volts on the + lead; but with the Seasonic, they are choosing to regulate the - side, it seems. Doesn't matter, of course, just curious.

Mike - when you and I discussed the Zalman, we concluded that the built-in fan was actually better, at low voltage, than the Panaflo - quieter and higher airflow. You had me insert a 22 ohm resistor in the circuit, and the results were great. Have you done likewise in the Seasonic? Your review criticises the ADDA fan; would you recommend swapping the ADDA for a Panaflo, AND inserting a resistor, or just swapping fans?

With the Seasonics, I do a straight fan swap. The Panaflo doesn't start right away, but once it does start spinning, it rarely goes up anyway. When you get close enough, at 4.5V, the fan in the Nexus sounds smoother than the Panaflo at the same voltage. BUT the difference is really hard to hear under normal circumstances. I've mentioned else where that the "M" version of the Panaflo sounds abou the same but can ramp up to much higher airflow, which makes it safer for those who push their systems really hard. So far, my Panaflo L modded Seasonics are doing just fine.

I am not a big fan of most ADDA fans, but for its price, the Seasonic is a good option. I prefer the ActivePFC: it does save us all a bit of energy consumption. It also has no or very little electronic noise (whine).

I measured 4.3V across the terminals of the fan when it was actually being driven, at idle/default. It is what the fan really is fed. Neither the L or M Panaflos will start at this voltage. I've checked several samples of both the 300 and 400 as well as microATX models of the Seasonic & found the same start voltage.

I've measured about 160VDC on three different PSU heatsinks. With one it was probably because the transistor was mounted against the heatsink without any insulation, but on two others, a Delta and an Antec, the transistors were insulated, but one leg of the heatsink was soldered to the same copper circuit board area that was soldered to the high voltage filter capacitors.

A couple of comments I'd like to add:
I've never seen a Seasonic PSU at any of my local pc stores. Which retailer can I see one at?

And please be careful fellow enthusiasts! We don't need an obituary page on Silent PC Review, except for dead power supplies like cschofie's.