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FrozenGate by Avery

converted computer psu

Maybe PC PSs, wall warts,and other laser power sources need thier own section. To those less advanced on these ,like me, the more I read the posts the more confused I feel.
I am sure I am not the only one. I have a whole box of harvested PC PSs and as yet am afraid to use any of them for anything. A good photo rich tutorial on the conversion of them would be a good thing. A dummies guide if you will. TMI is always better than not enough. I feel like my tiny brain is like a small HD- full atm and hard to store new data. I am great at taking electronics apart-- but repairing, adapting use, and getting them back together is often my weakness.---but thanks for all the above info....hak
 





My convented lab atx psu need a load on the 12V rail to run. It does not 'explode' or 'self destruct' without a load, it just switches itself off.
 
hakzaw1 said:
Maybe PC PSs, wall warts,and other laser power sources need thier own section. To those less advanced on these ,like me, the more I read the posts the more confused I feel.
I am sure I am not the only one. I have a whole box of harvested PC PSs and as yet am afraid to use any of them for anything. A good photo rich tutorial on the conversion of them would be a good thing. A dummies guide if you will. TMI is always better than not enough. I feel like my tiny brain is like a small HD- full atm and hard to store new data. I am great at taking electronics apart-- but repairing, adapting use, and getting them back together is often my weakness.---but thanks for all the above info....hak
Click to expand...

there are loads of tutorials on the net already.

How to Convert a Computer ATX Power Supply to a Lab Power Supply - wikiHow

ATX to Lab Bench Power Supply Conversion
 
Computer power supplies will work and there are plenty freebies to be had from dead or obsolete systems.... but, they are bulky and a waste of space for a projector. You can find nice compact fanless quiets power supplies that will give you exactly the power you need without weird resistors or other hacks for not much money at all.
 
ndrew2505 said:
there are loads of tutorials on the net already.

How to Convert a Computer ATX Power Supply to a Lab Power Supply - wikiHow

ATX to Lab Bench Power Supply Conversion
Click to expand...

Thanks for the links- sorry I did not do a proper search.



carmangary said:
Computer power supplies will work and there are plenty freebies to be had from dead or obsolete systems.... but, they are bulky and a waste of space for a projector. You can find nice compact fanless quiets power supplies that will give you exactly the power you need without weird resistors or other hacks for not much money at all.
Click to expand...
THANKS for the info.
 
It is my understanding that newer power supplies do not require a load to function or remain stable. However, most of the power supplies that I mod are in fact older models that have been swapped out of CPUs for newer ones, so I tend to include a small load such as a 10 watt resistor just to be safe.

HIMNL9 said:
Probably the old models still requires an external load, anyway .....
Click to expand...

Cyparagon said:
I must have an older one or something. As far as I can see, it works fine without any load
Click to expand...
 
My psu can supply any current on the 3.3V rail. I've read that you need to connect the sense pin to the 3.3V to make it work, but as soon as I go past a small current just shuts off. Anyone know why? :(

Pictures:
P5310011.jpg


The jumper is shorting the power-ON pin to ground. In this picture the 3.3V sense pin is not connected tho the 3.3V rail (it doesn't seem to care, it shuts off anyway). All of the 5V, 12V rails etc. are connected in parallel respectively in the motherboard connector pcb.
P5310010.jpg


P5310004.jpg


Out of view there is a load on the 12V rail to keep it on.
P5310002.jpg
 
From what I've read, the sense wire, (green one I'm assuming you're asking about?) needs to become grounded, not connected to the 3.3v rail.

Perhaps you also ought to try putting the load on the 3.3V rail instead of the 12V rail. I read to use the 3.3V rail and it will be fine, plus it will be less current for the resistor to handle. Hope this helps!
 
What color is the wire that goes to the sense pin? I don't believe I ever connect that to anything and my PS works fine. What you say regarding the shut off is not uncommon though. These power supplies have built in shut-offs and safeties to detect a short and shut the PSU down. However, if you connect a load to the power supply that take a large initial surge current, the PSU can mistake it for a short and shut itself down. I have connected my PS-ON wire to NC pushbutton switch, so if the power supply shuts down, I can use that to reset it.
 
Look, I've made a connection between pin 13 and 14. This makes the psu run. I can draw large currents off of all the rails except the 3.3V rail. I've tried connecting pin 11 together with pin 1 and 2, but it makes no difference. It just shuts off even when I try do draw a little current form the 3.3V rail.

6bcb9230.gif
 
Theoretically you should have 100W or thereabouts available on the 3.3V rail.

You may have a faulty 3.3V regulator in the supply.

Check the side label on the power supply itself.

3.3V amp rating? Total wattage? Brandname?

Most crappy supplies will die if you try to pull too much current from any one rail without load on another rail.
 
Does anyone know of a good ATX power supply to buy new that works well? I need about 20A of 12V power.

We should post model numbers and specifics of the supplies, though it would probably be hard to find a older PSU that is still for sale.

I'm thinking I might just buy a regular pyramid PSU. If I had some extra ATX supplies I might mess around with it, but I don't.

On a small sidenote, I've been trying to figure out how to make the Casio projector power supply run after it has been removed and have had no luck so far. I've got one spot with good 13.8V power, but I'm pretty sure it is not regulated and it is only good for about 3A. This thing must be able to put out more than that, so if anyone wants to help me figure this out, PM me and I will send you one to poke around on.
 
Sorry for the double post.

I've since stopped my conversion project, it turns out the supply has bad capacitors (bulging, leaking).

I've also compiled a list of criteria for those who would be interested in (properly) converting an ATX power supply.

________

Firstly, don't buy a generic power supply. At the $25 or so price point, most are garbage and won't stand up to any heavy usage.

They're cheap for a reason. They use low-quality components, inflated output ratings and virtually no output filtering/conditioning.

Most will have absurd amounts of ripple, along with voltages which may be out by 2V or more depending on load.

Most of us wouldn't trust our PC to that sort of thing, so why should we trust our lasers with one?

When selecting a unit, go for a brand-name manufacturer such as Antec, Seasonic, Channel Well Technology, Corsair or Coolermaster. Even their budget models feature superb build quality (speaking from personal experience here), and it will be worth the extra $$$ you pay for them.

Secondly, make sure the unit has single 12 and 5V rails. Split-rail power supplies are unstable under high load, and drawing too much current from one rail may cause it to catastrophically fail. The specifications will often tell you how many rails there are- read them before buying.

Thirdly, although it may not seem necessary to run with a dummy load, it is advisable for purposes of voltage stability.

Even expensive power supplies will have voltage fluctuations with little to no load, and this does have the potential to affect the operation of laser drivers. Once again, you could rely on your driver to catch it, but it's better safe than sorry.

All you would need would be a 100 ohm 25W resistor on the 12V and 5V rail (tapped from the main ATX plug). It's not much, but it does wonders for stability, especially with cheap power supplies.

Here's an example I've pulled from NewEgg. As you can see, I'm a fan of Seasonic due to their fantastic build quality (they are also OEMs for Corsair).

Newegg.com - SeaSonic SS-300ET Bronze 300W ATX12V V2.3 80 PLUS BRONZE Certified Active PFC Power Supply - Power Supplies

300W unit with Active PFC, it should be enough to meet the needs of most people.
 
Sorry for the double post.

I've since stopped my conversion project, it turns out the supply has bad capacitors (bulging, leaking).

I've also compiled a list of criteria for those who would be interested in (properly) converting an ATX power supply.

________

Firstly, don't buy a generic power supply. At the $25 or so price point, most are garbage and won't stand up to any heavy usage.

They're cheap for a reason. They use low-quality components, inflated output ratings and virtually no output filtering/conditioning.

Most will have absurd amounts of ripple, along with voltages which may be out by 2V or more depending on load.

Most of us wouldn't trust our PC to that sort of thing, so why should we trust our lasers with one?

When selecting a unit, go for a brand-name manufacturer such as Antec, Seasonic, Channel Well Technology, Corsair or Coolermaster. Even their budget models feature superb build quality (speaking from personal experience here), and it will be worth the extra $$$ you pay for them.

Secondly, make sure the unit has single 12 and 5V rails. Split-rail power supplies are unstable under high load, and drawing too much current from one rail may cause it to catastrophically fail. The specifications will often tell you how many rails there are- read them before buying.

Thirdly, although it may not seem necessary to run with a dummy load, it is advisable for purposes of voltage stability.

Even expensive power supplies will have voltage fluctuations with little to no load, and this does have the potential to affect the operation of laser drivers. Once again, you could rely on your driver to catch it, but it's better safe than sorry.

All you would need would be a 100 ohm 25W resistor on the 12V and 5V rail (tapped from the main ATX plug). It's not much, but it does wonders for stability, especially with cheap power supplies.

Here's an example I've pulled from NewEgg. As you can see, I'm a fan of Seasonic due to their fantastic build quality (they are also OEMs for Corsair).

Newegg.com - SeaSonic SS-300ET Bronze 300W ATX12V V2.3 80 PLUS BRONZE Certified Active PFC Power Supply - Power Supplies

300W unit with Active PFC, it should be enough to meet the needs of most people.
 
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