What can you actually mod in a PSU besides caps?

[ethaniel]

I have noticed that several hardware parts have voltmods, pinmods, pencil mods and capacitor change/replacement, but the only thing I have found about PSUs on the net are modifications to turn an ATX PSU into a bench/lab power supply. I know it's possible to replace caps in a PSU, but I was wondering what else can you do to, well, "make it better". I'm not talking about "turn a 300W PSU into an über-monster 800W PSU", but little adjustments. "Tweaking", if you want to call it that way.

[370forlife]

Re: What can you actually mod in a PSU besides caps?

I often upgrade the secondary schottky diodes (less heat, more efficient, more stable voltages,) as well as upgrading the capacitance of the capacitors. Putting in a transient filter or upgrade it as well as a higher capacity bridge rectifier or add one if it uses the ol' 4 diode treatment. Me and a couple other members have even swapped transformers and heatsinks.

Upgrading the capacity of the secondary's will also help insure that the primary will blow up before the secondary to save your connected hardware.

If you want to turn it into a lab power supply simply short the green wire on the 20 pin connector to any negative, it will jump start it (unless it needs a minimum load, in which case the fan may tick once until you get enough of a load)

[c_hegge]

Re: What can you actually mod in a PSU besides caps?

I've also known people to tweak the fan speed, making the fan run quieter by adding a speed controller or running if from the 5v rail (although you need to be careful when doing this to make sure you don't overheat the PSU)

[etnietering]

Re: What can you actually mod in a PSU besides caps?

There's all sorts of stuff you can do. From replacing output capacitors and adding input filtering on the easy end to replacing transformers and adding an IC based 5vsb circuit on the trickier, more difficult end.

Changing secondary side capacitors is easy, all it takes is a simple swap.
Adding secondary side inductors is also easy. If there aren't any, just remove the jumper wire and solder in the inductor.
Fan swapping is easy. Just unplug/unsolder and unscrew the old fan, and then plug/solder in and screw in the new fan.
Improving the input filtering is easy. Add X capacitors between H and N, Y capacitors between N and G, and H and G, add filter coils along H or N. The silkscreens are usually easy to follow.
Adding a bridge rectifier is easy. Just remove the 4 diodes, or whatever's there and add in a bridge rectifier. Make sure the +, -, and AC leads go where they're supposed to though.
Swapping primary side capacitors is pretty easy. Going with larger capacitance can give you cleaner power and improve hold time, but may have a negative effect on the power factor.
Upgrading secondary side rectifiers isn't quite so easy. You may have to take the heatsink out, which is a pain. Most times Schottkys will be fine, but occasionally you'll need an ultrafast, which can lead to multiple component swaps and troubleshooting headaches.
Upgrading the primary side drive transistors is more complicated. Not only might you have to take out the heatsink, but you'll have to make sure you have the right kind of transistor (FET vs. BJT) and that they'll work with the design of the power supply.
Replacing transformers is fairly complicated. You'll have to remove the old transformer (which requires solder sucker/braid/whatever), may have to remove both heatsinks, and make sure the different taps/windings line up with the old one and are compatible with the board.
Replacing the entire 5vsb circuit is the most complex thing I've tried. And I'm not even done with it. You have to remove components, maybe cut traces, build a new board, and wire everything in.
You can also check out my thread in the power supply section about adding a circuit to keep the fan running after you turn the computer off.
I'm sure there's much more you can do, and it'll get even more complicated, time consuming, and probably expensive...

There are lots of people here with knowledge and experience who are happy to help you should you want to upgrade or 'tweak' a power supply.

[ratdude747]

Re: What can you actually mod in a PSU besides caps?

i have seen units that seem to be all modded except the pcb and metal box....

YAY! post #2500!

[bravotronics]

Re: What can you actually mod in a PSU besides caps?

I do lots of PSU mods for personal use, mostly cosmetical or space saving for customized cases, but sometimes add fan speed controls (using 3 pin variable voltage regulators), add or remove hard drive power cables, replace the input thermistor when it overheats due to under-rated components, add/mod/replace heat sinks, caps, input filters, etc.
It's always important to test the PSU with dummy loads (I use Halogen 12v bulbs) before connecting it to the computer again, just in case.....

[stj]

Re: What can you actually mod in a PSU besides caps?

fit a quality LED fan,
and an led for the 5v standby.

i do that, just so i know they are actually running.

[inuyasha.rules]

Re: What can you actually mod in a PSU besides caps?

Don't forget sleeving the cables, buliding a plexi case, getting heatsinks anodized to match case theme, larger quieter fans, and I've even heard of replacing the heatsinks with waterblocks and eliminating the fan alltogether, although I reccomend leaving a fan there to cool the caps and whatnot that you can't heatsink. Come to think of it I saw somewhere someone built a water cooled plexi case filled with transformer oil and mounted it in the front drive bays. He used a small grunty high torque 40mm fan to circulate the oil which also kept the noise down.

Edit: sorry for the thread lazerus lol

[Krankshaft]

Re: What can you actually mod in a PSU besides caps?

I saw the dielectric oil PC too.

Hate to see the mess if that container sprung a leak. Not to mention if the oil got contaminated and became conductive it would create a giant short.

Putting water cooling on a CPU is bad enough on the PSU in the vicinity of mains voltage is just foolish.

My upper radiator hose just blew on my Honda and I'm still cleaning up the coolant spray. If there is fluid and rubber hoses you'll eventually have leaks.

[inuyasha.rules]

Re: What can you actually mod in a PSU besides caps?

That's why im planning on doing all copper for everything when I finally go wc. Copper water blocks, copper radiator, and a combination of solid and soft copper tubing, all brazed together. But that will make it a pain in th a** to change stuff. I can't really think of anything that would contaminate the oil enough to cause a short, other than a ton of caps blowing but IMHO you would have stability issues before it was causing a short.

[everell]

Re: What can you actually mod in a PSU besides caps?

I decided to add a LED indicator to my psu like the one on a Bestec ATX-250 12Z. It was a more interesting circuit than I expected because it tells you three things about the computer.

First, when the computer is plugged into a wall outlet, the LED indicates that the 5vsb is working. The measurement from the LED indicator is actually taken from the PS-ON circuit which gets its power from the 5vsb.

Second, when you push the power on button on the computer, this signals the south bridge chip to take the PS-ON in the power supply from high state (5vsb) to low state (ground). This is like shorting the green wire to a black wire on the power supply plug. But you have to remember that the south bridge chip is what actually does this. So the LED indicator light goes off. This means that the south bridge chip is working.

Third, the LED indicator also monitors the PGO (power good out) signal from the power supply supervisor chip. When PGO is good, the signal is high (5 volts) and the LED comes on. When PGO is bad, the signal is low (0 volts) and the LED is off.

Power up sequence for the LED indicator is: when plugged into wall outlet, LED should come on. When you push the power on switch, the LED should blink off then on. This indicates that the south bridge chip turned the power supply on and that the power good signal came on quickly.