DOA G4/DA/466 = ATX shenanigans . . .

[CelGen]

Resistors burning up the the PSU might be signs that one or more of the switching FETs have shorted out and it's forcing current down the line, destroying what is the point of highest resistance (in this case, not the traces).
ATX PSU conversions suck to do. First at least check to see if any of your FETs have shorted before you fully call the original PSU a write-off.

[Trash80toHP_Mini]

I'll definitely check that out too, when the time comes.

It's back burnered for the DA Resurrection for the nonce. I moved the lowly ATI Card to the QS'02 because it runs my 1080p Monitor just fine. I yanked out the ATA Card to install in my Dual Core ATOM board's PCI Slot to finalloy get it up and running (since my girlfriend gave it to me last June ) because I haven't got any SATA Drives yet, but soon!

I'll be setting up the QS'02 before taking up the Resurrection Project.

I might just get a better DA to upgrade my baby and have some spare parts around.

[techknight]

Well, this is just a dumb thought, but if you needed 24V to power the monitor that an ATX power supply wont do, Another engineering hack approach is to find a dual-rail 12V power supply, some gamer power supplies have 2 separate 12V rails/windings in the ATX power supply. Find the rail opposite of the one that is used for regulation, remove the original rectifier, and form a diode/capacitor voltage doubler rectifier circuit off that particular winding.

Another/easier approach would be to experiement with some magnet wire on a cheap power supply, and wrap the transformer with another layer of magnet wire to derive a new winding for your 18v/24v/28v setup. This would work as well.

You could use a TO-220 based 7818 regulator as well for the 24v or 28v to 18V, but only at 1 amp or so.

[Trash80toHP_Mini]

Sounds like it would be a LOT less expensive to buy two smaller, NON-GAMER ATX PSUs and easier to build a black box to output the higher voltages.

Me no keen on magic smoke emanations or flames escaping . . .

[techknight]

I just like to get my hands dirty

Black Box Approach: Linear Technologies has a good set of DC-DC buck/boost converter ICs and design guides. Some of them even have development boards with all the components already in place.

Here is a datasheet to an IC from National SemI:
http://www.ti.com/lit/ds/symlink/lm2586.pdf

The circuit you will be interested in, is page 24 of the PDF.

[techknight]

the super-d-duper-ba-pooper easy approach is this:

http://www.virtualvillage.com/12v-to-24 ... 2-013.html

[Trash80toHP_Mini]

That one looks promising! Not that I know what I'm looking at, but the pic is nice and the specs sound good!

[Bunsen]

but it's 2A shy of the DA's 24A spec on the 3.3V rail . . . probably doesn't matter?

Probably not.

two smaller, NON-GAMER ATX PSUs and easier to build a black box to output the higher voltages.

If you're thinking (and it is hard to tell sometimes ) that you can add two 12V supplies together to make 24V - don't. They share the same ground, so you will short *at least* one of them. That's a smoke-escape situation.

Either of the two suggested and linked items for 12-24V boosting will work. Personally, I think a separate 24V mains adapter is the way to go - you are then putting that much less current demand on the 12V line of the ATX supply. (For example, 4A @24V will draw >8 amps from the ATX)

[techknight]

and most high quality gaming power supplies will hold 30 or so amps on the 12v rail.

[Trash80toHP_Mini]

From a PM:

Regrettably, you can't put two 12V lines in series that way, because they're actually in parallel coming out of the PS. If they were two truly independent sources that did not share a common ground, you could do it, but alas, precisely because that's what you'd want, Murphy ain't giving it to you.

I read this as: it is possible to connect two independent PSU 12V outputs together as they DO NOT share a common ground rail inside the same PSU. Two 12V lines from two independent PSUs staged in series ought to give 24V as I understand it.

True they each share the common ground on the A/C in feed, but that's not the same as sharing the same ground rail within a single box outputting two parallel 12V Rails, AFAIK.

Everything shares a common ground . . . mother Earth!

[techknight]

If the power supply is NOT grounded to earth on the AC line, you can in theory put 2 power supplies in parallel.

But the easiest thing to do i guess is find an old printer power supply brick. most were 24v. some were 32v. And use it. Ive got dozens. some are 18V, some are 24v.

Instead of having another cord hanging out the back through a slot cover, you could open up the main ATX PSU and just tie into the AC side. So the power brick AC comes off the ATX AC. All concealed with a single power cord coming out.

if you wanted to get fancy, you could run the 24V output through the normally open connection of an automotive relay, and power the relay's coil from the 12V power. So the 24V feed doesnt come through unless the machine powers on.

Just a thought...

[Trash80toHP_Mini]

I may have misinterpreted tomlee59's message, I haven't heard back from him.

Power Supplies are black magic, that's why it's nice to have a black magician around . . .
. . . ojfd, where are you? HELLLPPPPP!!!!!!!!!!!!!!!!!

The printer power supply sounds good, I'd run it off the Monitor Power Outlet of the PSU (if that will work as it'd be a distinct Power Rail in its own right) and jack its output into the converter board. That's assuming that the power on button of the ADC Monitors is something more on the level of a 5V standby power circuit/signal.

The DA is on a back burner ATM, I need to concentrate on adapting my skinny ATX PSU as the Soft Power capable replacement for my well and truly blown IIsi PSU. I need enough juice to run my Rocket and at least a couple of other cards in there for the SuperIIsiHack™

That skinny one doesn't have a switched outlet for a Monitor on the back, which I'd like to add. Would that be a possibility, or is there too much missing from the donor to do such an aftermarket upgrade?

If I can get that up and running, we'll see if we can get a beefier unit into a Q700/IIci PSU Case so that olePigeon can finally get his two Rocket IIci off the launch pad.

[MacJunky]

if you wanted to get fancy, you could run the 24V output through the normally open connection of an automotive relay, and power the relay's coil from the 12V power. So the 24V feed doesnt come through unless the machine powers on.

As I seem to recall the 24v is the standby rail, so may as well just leave it fired up all the time. unless you wanted to set up something silly that dropped the voltage down to 5-10 when the 12v rail was inactive. but really.. *shrug* May as well just put in a switch or flip off the power bar it is on or something.

[techknight]

Looks like I am going to have to locate me one of these machines that is dead, so I can do some hackery.

[Bunsen]

Power Supplies are black magic

If that's how you feel about them, then please - use a wallwart

[Trash80toHP_Mini]

Actually, it was my middle little brother, the mechanical engineer who does packaging for blade servers, who told me the electrical engineers consider the PSU engineers to be practitioners of a Black Art . . .

. . . I'm more of the Tim the Tool Man Taylor Type, but with enough expertise to be really dangerous in many a field!

. . . and me likes zaps, flames, sparkles and pops, so me keeps fire extinguisher close at hand.

[techknight]

Hm.. ive never thought of power supply engineering being a black art.

ive done alot of engineering/hacking of power supplies, I havent done a complete build from scratch of a 120v supply though. only 12v for car audio, have I built custom power supplies for. Even used an MCU to run the entire thing including the PWM output to drive the mosfets.