Author Topic: Spontaniously Exploding Bench PSUs  (Read 14913 times)

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Offline Cyberdragon

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Spontaniously Exploding Bench PSUs
« on: June 07, 2017, 05:19:27 pm »
 :o :wtf: What happened?! :scared:

*BZZZZZZAAAAAP*
Voltamort strikes again!
Explodingus - someone who frequently causes accidental explosions
 

Offline Tomorokoshi

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Re: Spontaniously Exploding Bench PSUs
« Reply #1 on: June 07, 2017, 05:28:32 pm »
Anyone around here have one of those?

Now THERE's an argument for, "Don't turn it on, take it apart!"
 
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Online PA0PBZ

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Re: Spontaniously Exploding Bench PSUs
« Reply #2 on: June 07, 2017, 05:31:26 pm »
Clearly something overheated, then caught fire and then it took the rest with it. Good luck finding where it started now...
Keyboard error: Press F1 to continue.
 

Offline fourtytwo42

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Re: Spontaniously Exploding Bench PSUs
« Reply #3 on: June 07, 2017, 06:16:09 pm »
Maybe your student decided to connect the output to the mains with a nail in the fuse! has been known :)
 

Offline schmitt trigger

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Re: Spontaniously Exploding Bench PSUs
« Reply #4 on: June 07, 2017, 06:18:55 pm »
An over-unit or cold-fusion event.  >:D
 
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Offline thm_w

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Re: Spontaniously Exploding Bench PSUs
« Reply #5 on: June 07, 2017, 08:01:47 pm »
Clearly something overheated, then caught fire and then it took the rest with it. Good luck finding where it started now...

Originally I thought the peltier probably overheated, due to inadequate cooling.
But from the wiring, it travels off to the right, so I don't think it is that.
 

Offline skarecrow

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Re: Spontaniously Exploding Bench PSUs
« Reply #6 on: June 07, 2017, 08:59:33 pm »
I've got the 30v 5a version of that power supply. Something about it made me very nervous the second I pulled it out of the box. Now I'm even more worried.

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Offline Cyberdragon

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Re: Spontaniously Exploding Bench PSUs
« Reply #7 on: June 07, 2017, 09:20:37 pm »
I've got the 30v 5a version of that power supply. Something about it made me very nervous the second I pulled it out of the box. Now I'm even more worried.

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"Don't turn it on, take it apart!"
*BZZZZZZAAAAAP*
Voltamort strikes again!
Explodingus - someone who frequently causes accidental explosions
 

Offline madires

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Re: Spontaniously Exploding Bench PSUs
« Reply #8 on: June 07, 2017, 09:38:24 pm »
Overrated? Cheap components? Poor thermal design? Assembly fault?
 

Online rdl

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Re: Spontaniously Exploding Bench PSUs
« Reply #9 on: June 07, 2017, 09:57:26 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
 
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Offline skarecrow

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Re: Spontaniously Exploding Bench PSUs
« Reply #10 on: June 07, 2017, 10:01:21 pm »
I've got the 30v 5a version of that power supply. Something about it made me very nervous the second I pulled it out of the box. Now I'm even more worried.

Sent from my XT1565 using Tapatalk

"Don't turn it on, take it apart!"
A-paaaaaaahhht!

I may do just that this weekend if I'm not too busy with other things.

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Online Vgkid

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Re: Spontaniously Exploding Bench PSUs
« Reply #11 on: June 08, 2017, 12:20:57 am »
I have one that I was tasked to fix, that assploded. I will post pics if you guys want them. Whatever died, took the transformer with it (yihua 3010 I believe)
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Offline abraxa

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Re: Spontaniously Exploding Bench PSUs
« Reply #12 on: June 08, 2017, 06:22:21 am »
Since there were high currents drawn when it went belly up it makes me wonder if maybe the ESR of the output caps is too high, causing excessive heat due to high ripple currents because of the high load? Or maybe some output-side FETs are undersized? But then again I wouldn't expect a SMPS to have FETs on the output side in the first place...

Or maybe I'm overthinking this and some PCB traces are simply too thin and started to glow :)
 

Offline CopperCone

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Re: Spontaniously Exploding Bench PSUs
« Reply #13 on: June 08, 2017, 06:33:07 am »
This makes me wary of plastic instruments. If it was near the edge of a table, what could have been a simple smoke event could have turned into a pile of burning shit falling on a flammable chair with someones coat on it. (old) Sorensen (quality brand) does this with their power supplies too, the front face is basically held on by plastic clips sandwiched down by the case cover.

I had a bunch of fire wood roll out of an overloaded chimney once... Scary shit, especially if the fire is started by a MOV when its off. This is a good reason why the protection circuitry should be placed after the switch, and why full burn testing is a good idea.

Mine are high up on a shelf too (with power connected). Thankfully the PCBs are pretty well connected to a heat sink that is connected to the chassis base, but still, i would not want a ball of flaming shit to fall out of the power supply and spray all over the room! This shit made me paranoid. It's like a murder hole in a castle.

https://en.wikipedia.org/wiki/Murder-hole

« Last Edit: June 08, 2017, 06:36:09 am by CopperCone »
 

Offline RGB255_0_0

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Re: Spontaniously Exploding Bench PSUs
« Reply #14 on: June 13, 2017, 03:05:40 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
This one was "10A". Most I've seen are 3 or 5A rated. Perhaps this had been aftermarket modified in which case who is surprised it melted?

I wouldn't leave mine unattended though.
Your toaster just set fire to an African child over TCP.
 

Offline kalel

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Re: Spontaniously Exploding Bench PSUs
« Reply #15 on: June 13, 2017, 03:45:04 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
This one was "10A". Most I've seen are 3 or 5A rated. Perhaps this had been aftermarket modified in which case who is surprised it melted?

I wouldn't leave mine unattended though.

Is there no thermal cutoff built into these circuits, or is it something that does not apply for more extreme overheating cases, or is it simply impossible to fully protect against all possible overheating causes?
 

Online rdl

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Re: Spontaniously Exploding Bench PSUs
« Reply #16 on: June 13, 2017, 04:19:02 pm »
The 10 amp versions actually cost an extra $25. I don't think they're a safety hazard because of where they are made, but there's no way they can be anything but cheap garbage and I wouldn't risk having one in my home even if it was free.
 

Offline RGB255_0_0

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Re: Spontaniously Exploding Bench PSUs
« Reply #17 on: June 13, 2017, 04:34:59 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
This one was "10A". Most I've seen are 3 or 5A rated. Perhaps this had been aftermarket modified in which case who is surprised it melted?

I wouldn't leave mine unattended though.

Is there no thermal cutoff built into these circuits, or is it something that does not apply for more extreme overheating cases, or is it simply impossible to fully protect against all possible overheating causes?
Doesn't look like it (2 NTCs on the mains input, though). But it's only 3A limit - if I want more I have other options.
Your toaster just set fire to an African child over TCP.
 

Offline RGB255_0_0

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Re: Spontaniously Exploding Bench PSUs
« Reply #18 on: June 13, 2017, 04:46:33 pm »
The 10 amp versions actually cost an extra $25.
But has anyone done a side-by-side to see if they are using higher rating components? Just because it's more expensive doesn't change the argument that they weren't modified 5A ones to allow 10A.
Your toaster just set fire to an African child over TCP.
 

Online rdl

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Re: Spontaniously Exploding Bench PSUs
« Reply #19 on: June 13, 2017, 05:05:03 pm »
It would almost be worth the price to do a comparison if no one has done it already. I looked for 10 amp versions on ebay this morning, but it seems they are all "out of stock" now.

I have considered buying one of this type just to see how bad it is inside. It might actually be okay for the price and able to meet its specifications.

http://www.ebay.com/itm/15V1A-Precision-Variable-DC-Power-Supply-Clip-Cable-Digital-Adjustable-Lab-Grade-/390681828322
 

Offline RGB255_0_0

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Re: Spontaniously Exploding Bench PSUs
« Reply #20 on: June 13, 2017, 05:36:38 pm »
I see http://www.ebay.com/itm/30V-10A-Adjustable-DC-Power-Supply-Precision-Variable-Dual-Digital-Lab-Test-110V/391321591608?rt=nc which has sold 1,000+ units already. I'm leaning towards the on fire one was likely isolated and not something to be too concerned about in all honesty.
Your toaster just set fire to an African child over TCP.
 

Offline tooki

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Re: Spontaniously Exploding Bench PSUs
« Reply #21 on: June 14, 2017, 05:49:08 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
Out of curiosity, where? I'm not seeing them for under $60 shipped.
 

Online rdl

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Re: Spontaniously Exploding Bench PSUs
« Reply #22 on: June 14, 2017, 05:58:26 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
Out of curiosity, where? I'm not seeing them for under $60 shipped.

I had to later qualify that statement.

The 10 amp versions actually cost an extra $25.

So there may be more differences than just the labeling.
 

Offline donotdespisethesnake

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Re: Spontaniously Exploding Bench PSUs
« Reply #23 on: June 14, 2017, 06:34:20 pm »
Anyone around here have one of those?

Yes... thanks for the heads up!

My general rule is that China && cheap == fire.
Bob
"All you said is just a bunch of opinions."
 
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Offline tooki

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Re: Spontaniously Exploding Bench PSUs
« Reply #24 on: June 14, 2017, 07:28:22 pm »
Those sell for under $35 shipped. Why is anybody surprised it burned up?
Out of curiosity, where? I'm not seeing them for under $60 shipped.

I had to later qualify that statement.

The 10 amp versions actually cost an extra $25.
I know, I wasn't even talking about the 10A versions later mentioned. I'm not seeing 5A ones for under $60 shipped. (OK, I came across one for $55. But nowhere near $35.)
 


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