Hi

I used to review ATX power supplies many moons ago for a popular website and have ten or so still in my possesion but the question is are they still safe to use?

The power supplies are probably going on for around 10 to 12 years old. They were used for about 24 hours, put back in their boxes and stored inside the house ever since.

Opinions differ on-line from it shouldn't be a problem to the electrolytics will have degraded and magic smoke will probably be the result of plugging them in.

I don't want to move them on if they are going to cause damage days, weeks or months down the road. I'd rather dispose of them but it seems a shame.

Are these power supplies still viable are should I just get rid?

Help appreciated.

 

The supplies, if they came from reputable companies, will have an inline fuse. They should fail safe, if they do fail.

If you have a need for them, I would power them up, unloaded, for 24 hours. Otherwise, donate them or just e-trash them. Do try to salvage worthwhile components from them, though.

Other members will have different suggestions. All of them as valid/ stupid as mine.

 

You could try them on a couple of 12V lamps as loads to see if they work ok.

 

Are these power supplies still viable are should I just get rid?

I don't have a definitive answer, but I powered up 3 old supplies relatively recently. Two smoked and one was fine.

I intended to use all three with breakout boards; mainly for high current 12V.

 

I still use 10-15 year old boxes as servers that are still running fine 24/7.

 

Depends on their capacitors... So called Computer Grade capacitors are typically a "better" grade long life cap. Blow the dust out and clean the fan making sure it runs free. Check caps for leakage or bulging, power it up, and check the output for excessive ripple. If the magic smoke appears there is a problem...

 

I recall reading recommendations of running caps initially with low voltage allowing to "re form" the dielectric. Not practical with an assembled PSU.
Maybe with a variac?

 

Always a good idea to start up older equipment at a lower voltage with a variac!

 

I am using a few that have been running 10 ~ 15 years 24/7. Years ago like you I helped with testing ATX PSUs. Still have my early proto type load bank I made. Anyway, I would peek inside look for any leaking caps but I would try what you have out. Been so many years I forgot the name of the site I helped on. Real nice people.

Ron

 

Always a good idea to start up older equipment at a lower voltage with a variac!

Have caution! When I worked for HP, we had a power brownout. It smoked all of the computer power supplies in the office!

 

Have caution! When I worked for HP, we had a power brownout. It smoked all of the computer power supplies in the office!

I would assume it was because they were under load? I can't see how just the power supply alone would have a problem unless maybe it was a switching PS? Weren't the old ATX supplies linear?

 

You could use the old trick of adding an incandescent 120V lamp in series when you power up the supplies.
The very non-linear resistance vs. current of the lamp will limit the current if it's faulty, but should pass enough current to power it up with no output load, if it's okay.
The no load input current of an ATX supply is typically 10-100mA.
Try a 100W lamp to start, which should readily power a good supply with only a few volts drop, but will limit the current (or surge current) to <1A (for a 120V unit).

Note that the output voltage of an ATX is generally not properly regulated without a small 5V load current.

 

Weren't the old ATX supplies linear?

All of the ones I have worked with going back to the 80 were SMPS designs.

Note that the output voltage of an ATX is generally not properly regulated without a small 5V load current.

Some did but today most no longer require a minimum load. I always used a 10 Ohm 10 Watt load on the 5.0 V rail for those needing a load.

Ron

 

if you have no need for them, in the bin they go unless someone is willing to take them.
if you can use them, decide what you actually expect from them.
if they are expected to last, simply replace all electrolytic capacitors (preventive measure).

 

You could use the old trick of adding an incandescent 120V lamp in series when you power up the supplies.
The lamp will limit the current if it's faulty, but should pass enough current to power it up with no load, if it's okay.
Try a 100W lamp to start.

 

I've had a couple of them sitting on the shelf for years thinking I might use them for their fixed 5 & 3.3VDC and ±12VDC as a bench PSU for digital experiment work. So, popped one open and (along with a ton of dust) there are LOTS of small electrolytics, ferrite center coils, and toroids as it is indeed a SMPS. Only 1 medium sized electrolytic PSU rectifier filter cap though. Somewhere I seem to remember an article on AT PSU conversion for bench use that had the notes for tying the 5VDC out to the sense circuit to allow it to fully turn on.

 

I've had a couple of them sitting on the shelf for years thinking I might use them for their fixed 5 & 3.3VDC and ±12VDC as a bench PSU for digital experiment work. So, popped one open and (along with a ton of dust) there are LOTS of small electrolytics, ferrite center coils, and toroids as it is indeed a SMPS. Only 1 medium sized electrolytic PSU rectifier filter cap though. Somewhere I seem to remember an article on AT PSU conversion for bench use that had the notes for tying the 5VDC out to the sense circuit to allow it to fully turn on.

Sam if you take the ATX PSU to Bench Supply I suggest getting a pair of these ATX Breakout boards. The outputs are fused.

Ron

 

Of course they're less expensive on AliExpress:

My most recent purchase was:

 

Thanks for the heads-up. Ordered! $2.90 way cheaper than doing it piecemeal... Not to mention much faster plug and play!

 

Thanks for the heads-up. Ordered! $2.90 way cheaper than doing it piecemeal... Not to mention much faster plug and play!

Be sure to check the wiring of the "plus 4" on a 24 pin connector. Older ATX supplies won't be compatible, but you may be able to separate the "plus 4" part.