Could a PSU tester cause a power supply to start smoking?

[myaccount]

I got this PSU tester recently:
https://www.amazon.com/dp/B005CTCD6S

I used it to test one of my PSUs and it worked fine.

But I have another PSU - an old PSU that I got from someone off ebay about 10 years ago, which I ended up never using and it just sat on the shelf since then. I decided to use the tester on it. I plugged the PSU into the tester and turned the PSU on. After a couple seconds, the PSU started making a weird noise, and then smoke started coming out of the PSU. I quickly unplugged it.

Is there any chance the tester could have caused that PSU to start smoking? Or could the PSU have just died after sitting on the shelf for so long?

[stj]

Re: Could a PSU tester cause a power supply to start smoking?

i have seen in those, they cant damage anything.
your psu was faulty - just a lucky coincidence you hooked it to the tester instead of a system!

[momaka]

Re: Could a PSU tester cause a power supply to start smoking?

Nope, the PSU tester shouldn't be able to damage anything.

That said, those PSU "testers" are pretty much useless. I wouldn't really call them PSU testers. More like a device to see if a PSU turns ON - nothing more and nothing less. That said, just because a PSU turns ON doesn't mean that it's actually working properly. Likewise, just because the tester may say that it is bad doesn't mean that it is. I've seen cheap testers like that fail many high-end PSUs right out of the box, mostly because those high-end PSUs need a bigger load to have voltages properly in spec.

The best way to check a PSU is to connect it to a load and measure ripple/noise with a scope. But obviously not everyone has the time and equipment to do that. So instead, the best *easiest* way to check a PSU is to open it up and post some pictures here on BCN . Then we can tell you if there are things that you might want to look out for - like a gutless PSU, or perhaps a good PSU but with dodgy output capacitors.

[budm]

Re: Could a PSU tester cause a power supply to start smoking?

Capacitors sitting unused for 10+ years should be slowly reformed before applying full Voltage to them.
Just look up 'reforming electrolytics capacitor'
http://www.qsl.net/g3oou/reform.html

[dmill89]

Re: Could a PSU tester cause a power supply to start smoking?

Nope, the PSU tester shouldn't be able to damage anything.

This one can (if the PSU is of very poor quality since it puts it under about 140W load):



But your "everyday" amazon/eBay/best buy/etc. "PSU tester" that doesn't put any significant load on the PSU won't (but like you mentioned it isn't much of a "test" either with no load).

[Th3_uN1Qu3]

Re: Could a PSU tester cause a power supply to start smoking?

Yeah, that kind of tester is just a multiple-input digital voltmeter, along with a little timing circuit to measure the rise time of the "power good" signal. Does not present any significant load.

[momaka]

Re: Could a PSU tester cause a power supply to start smoking?

This one can (if the PSU is of very poor quality since it puts it under about 140W load):
https://www.badcaps.net/forum/attach...1&d=1504916496
https://www.badcaps.net/forum/attach...1&d=1504916496

Nice!!!
Where did you get that one?

I still haven't built a proper load tester. That said, I have a NiCr 3000 Watt heating element from a dryer. I hooked up some jumper leads to the turns a few times and was able to load some of my PSUs to about 100 Watts. My idea is to build one with that heating element that can do at least 500 Watts with forced air cooling. Unlike resistors that can burn out, NiCr wire can take a tough beating, even with passive cooling only.

[dmill89]

Re: Could a PSU tester cause a power supply to start smoking?

Nice!!!
Where did you get that one?

eBay a few years ago. It was part of a test kit Seasonic sold to PC shops/techs in the early 2000s. It has two modes (jumper controlled) 75W and 140W, not enough to really load a modern PSU much, but definitely better then the cheap testers that don't put any load at all on the PSU (aside from the tiny bit to run the LEDs/LCD).

[Agent24]

Re: Could a PSU tester cause a power supply to start smoking?

If the PSU tester had a manufacturing defect which say, shorted +12v to the PWR_GOOD output or something, then I could see a possibility for damage...

[momaka]

Re: Could a PSU tester cause a power supply to start smoking?

If the PSU tester had a manufacturing defect which say, shorted +12v to the PWR_GOOD output or something, then I could see a possibility for damage...

Nope.

Supervisory chips are usually rated for -0.3 to Vcc as their operating voltage. With Vcc typically the 5VSB rail or the 12V rail (depending if the main PS is running or not), that makes it pretty much not possible to damage the supervisory chip on any of its inputs and outputs outputs.

Also, PG and PS_ON are typically in series with a resistor inside the PSU, so that alone will protect the supervisory in most cases.

eBay a few years ago. It was part of a test kit Seasonic sold to PC shops/techs in the early 2000s. It has two modes (jumper controlled) 75W and 140W, not enough to really load a modern PSU much, but definitely better then the cheap testers that don't put any load at all on the PSU (aside from the tiny bit to run the LEDs/LCD).

Awesome!

Actually 75 Watts / 140 Watts is perfect for testing PSUs in just about every office rig / low-end PC. It's only the mid-range and high-end gaming PCs with dedicated video cards that will usually pull more power and thus require a bigger PSU. But even then, 140 Watts is more than enough to test a PSU.

This Seasonic tester is a brilliant idea. They should make more of these.