One day was just terrible, very windy. Utility power kept going off and on. Then my PC PSU made a loud crackling noise and the power went off and came right back on, but they killed my PSU.

So I bought a new one. Today I opened it up and found the problem. On the neutral side existed some component that totally exploded -fried - burned away. The neutral line from power in, ran directly to this component. So I bridged it on the backside with solder, and the PSU once again works.

So i t was some kind of protection device, anyone know what it was?

 

That certainly popped well!
It will have been a negative temperature coefficient thermistor to limit the surge current on switch on.
If you can get a replacement for it that would be a good idea.
A couple of links...
http://www.powerelectronics.com/com...-limit-inrush-current-capacitive-applications
https://au.mouser.com/ProductDetail/Ametherm/SL22-5R012?qs=PVyXUKBeRH1IM//gwr4TiA==

I don't know if that one is the correct type buy if your replacement power supply is the same you could find out what is in that one.

 

Thanks, makes a lot of sense. I have several blown PSU, maybe one of them has this.
The PSU is a 650 watt model. New one is not the same, when one of these goes, I dont want to buy the same model again. This one I got on Ebay, has a "Lead Power " sticker. Model LP-650, It actually has been a good PSU for the money.

Do you think an 8 to 10 amp inrush surge is about right?

 

https://en.tdk.eu/tdk-en/373562/tec...ations---cases/always-on-the-safe-side/761864

I think too low of an amp rating will cause greater parasitic heating losses for the PSU, lowering the efficiency and wasting power, so it seems the 12 amp is likely a good choice. However, they want a lot to ship one item out (24$)... Buying something like this compared to the cost of the PSU, makes it not worth the repair. But I can use the PSU, my PC's are on all the time, 24 hours a day. Right now I dont even need this PSU.

I do have a blown Rosewill PSU 550 watt with popped caps. I see it has a blue looking ceramic disc thing in the input power, which may be one of those things. I was thinking all it needs is to be attached to the white 120vac line right off the plug socket, versus on the board.

 

So i t was some kind of protection device, anyone know what it was?

A soft start varistor?

 

Its been fine without it for now.
Looking at a failed 500w PSU, I cant find a surge device like this.
But I did pull off 2 common mode chokes and 2 capacitors. One was on the AC input board right after the AC power plug. The other is on the board. I also used the donor plug that plugs in the AC power to the main board. The mainboard had places for those things but they were not installed. You can notice my first picture set shows nothing there on the main board. Had to also cut a slot in the metal cover to hold the on-off switch.

So I added in some components, what will adding in those components achieve? Less noise radiating back out down the AC line? Anything else?
This pic shows the added on tiny board right after AC input.


This pic shows the main board additions. Coil common mode choke and yellow cap next to fuse. And they wrapped the ac in wire where connected to mainboard with another choke?



another view of little board with coil and cap, has also those little blue surge things.
I soldered short wires to join plug socket to little board, then hot glued to make it more rigid so it wont be flopping around.

 

Utility power kept going off and on. Then my PC PSU made a loud crackling noise and the power went off and came right back on, but they killed my PSU.

Check with your power company to see if they'll pay for the replacement.

Buy a surge protector to prevent it from happening again.

 

its always been on a surge power strip. Maybe the strip is no good.

 

its always been on a surge power strip. Maybe the strip is no good.

Try to get the power company to pay for the new power supply.

Does the power strip have a protection warranty? You might be able to get them to pay.

Collecting from either could be a hassle.

 

Its been fine without it for now.

Yeah, well.. It's like insurance. You can live without it until you need it then you're SOL.

Looking at a failed 500w PSU, I cant find a surge device like this.

You want an unused replacement! Varistors take a finite number of hits.

what will adding in those components achieve? Less noise radiating back out down the AC line?

Yes and vice versa.

Check with your power company to see if they'll pay for the replacement.

Or better yet he could just bite the bullet and buy one! They're not that expensive.

Thanks!

 

Sure could buy another one, but then why bother with this forum regarding repairs and information?

 

Sure could buy another one, but then why bother with this forum regarding repairs and information?

Mending an iffy power supply sounds like trouble ahead to me. I'll bet the value of the load and its uninterrupted operation outweigh PSU replacement cost? Or is it all fun and adventure with you?

Thanks!

 

Mending an iffy power supply sounds like trouble ahead to me. I'll bet the value of the load and its uninterrupted operation outweigh PSU replacement cost? Or is it all fun and adventure with you?

Thanks!

It is still working fine.
I am happy that I got it working. I cobbled together some old PC parts, ASUS MB from 2010 with AMD b95 4 core Phenom II.
When the PSU took that hit, the bios on the MSI board that it was running somehow took a hit, and I thought that MB died, refused to show any life so I got this other MB together to replace it. Turned out all I needed to do was remove the cmos battery on the MSI board and it booted up. It was dead, dead, dead, but not really dead.

I have had good results with MSI boards over the years.

 

Dude! Really! I'm happy for you! All I'm saying is that I'd replace the PS in a heartbeat if damage to the load or downtime would be more costly than the power supply! Sure! Practice and hands on experience is good! But this is sounding like DIY exploratory surgery as an alternative to a course in general anatomy.

Thanks!

 

I found a 9 amp SCK202R5 negative temperature coefficient thermistor in a failed Thermaltake PSU.
Installed it, and it works. It is raining all this week, and needed something to do.
Still not using this PSU, but I will be someday.