Question PSU keeps blowing 5A plug fuses ?

[O-451]

Ey up, first time I've had an issue like this. UK by the way, our plugs have fuses in them.

Specs:

PSU: Be quiet! Dark Power 13 750W​

Mobo: MSI Mag B550 Tomahawk Max WIFI​

CPU: AMD Ryzen 5 5600x​

GPU: Radeon RX 6800XT (Powercooler Red Devil)​

RAM: 2x16GB Corsair Vengeance LPX​

---

I built a new PC last August and it's been working swimmingly until this weekend. I was using it as normal, turned it off as normal, and then when I returned after 30 minutes it refused to turn back on. Upon inspection I found that the 5A fuse in the PSU's plug had blown. I replaced the fuse, and it blew immediately (probably a bit daft to try in retrospect).

​

I always have the PSU plugged into a surge protector.​

At no time did I hear a bang or fizz.​

None of the capacitors on the Motherboard seem to have blown.​

I have never overclocked any of the components.​

The only thing I can think that might have caused it is...
Our plug sockets have a little on/off switch. I don't crawl under my desk to flick them off with a finger, instead I lean back in my chair and use my foot. It's not as precise, and there are times where I'll keep the switch in the middle for a few seconds, quickly flicking power on and off - I believe that happened when I turned it off last.

---

I have yet to remove the PSU and attempt the paper clip test. I know it's safe but you can't undo decades of don't stick paperclips into electronics on a whim. And it's a bloody pain to remove the PSU to test it.

What I do next - get an RMA, buy a new one, or see if I can still use it safely - is all dependent on how buggered it is.

I'm also wondering how I can check if the other components are okay. Unfortunately I don't have a test rig lying about and the only thing I can really test with is a multimeter.

Any advice would be appreciated. Cheers.

 

[Ralston18]

Test the PSU with the multimeter. Should be no need to remove the PSU. Just test via the connectors.

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test because the PSU is not underload. However, any voltages out of tolerance make the PSU suspect.

= = = =

Not uncommon to use a foot to switch off power strips, surge protectors etc. but doing so should be avoided.

Does lend itself to eventually damaging/breaking things..... Basically a kick.

All the more so for common discount bin products. Cheap switches and unless thrown quickly (or not) may cause current surges that blow fuses, trip smaller breakers, or simply fry the served device(s).

And remember that surge protectors are measure in Joules and the protection is thus limited. One big surge or the cummulative effect of smaller surges rendering the surge protector ineffective and thus moot.

So a surge from another source or cause may be hitting the PSU.

= = = =

That all said, what is the reason for flipping the power switch?

Are you using the the Windows shutdown process to turn off the system and then the switch to cut power to the PSU?

 

[Viking2121]

I would do the paper clip test to turn it on, make sure you get the right pins and its unplugged from the wall and off before you do it though.

I would also plug some stuff into it like a case fan, old hard drive for a little load. See if it pops the fuse still.

Im worried about other components, a bad motherboard or graphics card could cause this as well, though the PSU should trip before the fuse blows from what I understand on them UK outlets. If it trips the fuse before the PSU goes into a fail safe, something is grounding out that shouldn't be.

 

[O-451]

That all said, what is the reason for flipping the power switch?

Are you using the the Windows shutdown process to turn off the system and then the switch to cut power to the PSU?

Lifelong habit.

It's probably worth clarifying for folk outside the UK that it's the switches on the mains socket I'm turning off with my foot, not the power switch on the PSU.

When shutting my PC down I use Windows's shutdown procedure, and a few seconds after my PC shuts down (after the lights go off and there's a soft audible click), I turn off the power switch on the mains socket.

 

[Satan-IR]

Unless you unplug the PC/PSU to plug anything else to the wall outlet there's no need to turn the plug/socket off. Neither the PSU, there's no need to turn it off between use as some users do that.

First thing I'd unplug everything (24-pin, 4+4-pin, PCIE auxiliary etc) and take the PSU out of the case. To isolate it from PC components and to test with papterclip or multimeter. I'd add a load to the PSU if available when doing papercliip test, like a molex fan.

Have you tried plugging anything else in the outlet? If it blows with other appliances too maybe the socket has a short, a loose connection, damaged pins, caused by corrosion etc.

Have you tried turning the PSU switch off and then turn the socket switch on? I would take PSU out now (if you haven't already) to test this so the PC is not connected to a possibe faulty plug or PSU. Do this and if the plug/socket fuse blows once you turn PSU on maybe the inrush current from PSU Off > PSU Standby trips/blows the fuse. There might be a short in the PSU too. Like PSU's own fuseable components. I hope no component after PSU is damaged.

 

[O-451]

Have you tried plugging anything else in the outlet? If it blows with other appliances too maybe the socket has a short, a loose connection, damaged pins, caused by corrosion etc.

I can confirm that both the outlet and the surge protector are okay.
When trying to diagnose the issue I took my PC to a different room and the fuse blew on a different outlet (with the same surge protector - but I doubt that's the issue).

I appreciate all the responses and suggestions so far. I'll try testing the PSU tomorrow with a clear mind and get back to you all.

 

[Satan-IR]

I can confirm that both the outlet and the surge protector are okay.
When trying to diagnose the issue I took my PC to a different room and the fuse blew on a different outlet (with the same surge protector - but I doubt that's the issue).

I appreciate all the responses and suggestions so far. I'll try testing the PSU tomorrow with a clear mind and get back to you all.

Just to make sure, was the surge protector between the PSU and wall outlet/socket every time you tested in same and other room (after it stareted blowing fuses)?

Asking because these surge protectors have been known to cause issues with PCs and PSUs. If yes, to eliminate the possibility that it's the protector try connecting the PSU directly to outlets/sockets without the surge thingy.

 

[Bob.B]

Ey up, first time I've had an issue like this. UK by the way, our plugs have fuses in them.

Specs:

PSU: Be quiet! Dark Power 13 750W​

Mobo: MSI Mag B550 Tomahawk Max WIFI​

CPU: AMD Ryzen 5 5600x​

GPU: Radeon RX 6800XT (Powercooler Red Devil)​

RAM: 2x16GB Corsair Vengeance LPX​

---

I built a new PC last August and it's been working swimmingly until this weekend. I was using it as normal, turned it off as normal, and then when I returned after 30 minutes it refused to turn back on. Upon inspection I found that the 5A fuse in the PSU's plug had blown. I replaced the fuse, and it blew immediately (probably a bit daft to try in retrospect).

​

I always have the PSU plugged into a surge protector.​

At no time did I hear a bang or fizz.​

None of the capacitors on the Motherboard seem to have blown.​

I have never overclocked any of the components.​

The only thing I can think that might have caused it is...
Our plug sockets have a little power switch. I don't crawl under my desk to flick them off with a finger, instead I lean back in my chair and use my foot. It's not as precise, and there are times where I'll keep the switch in the middle for a few seconds, quickly flicking power on and off - I believe that happened when I turned it off last.

---

I have yet to remove the PSU and attempt the paper clip test. I know it's safe but you can't undo decades of don't stick paperclips into electronics on a whim. And it's a bloody pain to remove the PSU to test it.

What I do next - get an RMA, buy a new one, or see if I can still use it safely - is all dependent on how buggered it is.

I'm also wondering how I can check if the other components are okay. Unfortunately I don't have a test rig lying about and the only thing I can really test with is a multimeter.

Any advice would be appreciated. Cheers.

Where is this 5a fuse is it in the psu or the surge unit or the wall socket?

 

[beyondlogic]

I can confirm that both the outlet and the surge protector are okay.
When trying to diagnose the issue I took my PC to a different room and the fuse blew on a different outlet (with the same surge protector - but I doubt that's the issue).

I appreciate all the responses and suggestions so far. I'll try testing the PSU tomorrow with a clear mind and get back to you all.

make and model of the surge protector? protector might look ok but they are pretty deceptive i also have used a surge protector never had what you described though

 

[beyondlogic]

Where is this 5a fuse is it in the psu or the surge unit or the wall socket?

hello just to clarify there normally in the plugs themselves.

that however doesnt mean that the actual surge protector can handle the load properly cheapo surge protectors can do that.

 

[Bob.B]

hello just to clarify there normally in the plugs themselves.

that however doesnt mean that the actual surge protector can handle the load properly cheapo surge protectors can do that.

Can you provide a link that shows a fuse in a plug?

 

[bill001g]

Can you provide a link that shows a fuse in a plug?

You must live in the USA like me. This seems to be a requirement for power cords in the UK. I was very surprised these are the old style glass tube fuses. The only thing I can think of is they are worried about the power cord itself starting on fire. The wires in the wall would be large enough that the circuit breaker would trip before they overload. The wires in a power cord though can be much smaller.

I have avoided this thread because I have know little about these cords. Maybe if there are different sizes of fuses in different cords maybe he got one from a device rated for lower power and accidentally swapped them.

 

[beyondlogic]

Can you provide a link that shows a fuse in a plug?

https://www.electricaltechnology.org/wp-content/uploads/2021/05/How-to-Wire-a-UK-Plug.jpg

 

[beyondlogic]

https://www.electricaltechnology.org/wp-content/uploads/2021/05/How-to-Wire-a-UK-Plug.jpg

https://www.checkatrade.com/blog/wp-content/uploads/2021/02/Plug-wiring-diagram.jpg

https://www.google.com/url?sa=i&url...ved=0CBIQjRxqFwoTCJDXkcrq1YUDFQAAAAAdAAAAABBI

uk plugs are designed with several features

live wire brown is delibrately made shorter so if you accidentally pull out the plug to hard that the live wire is removed from power first.
earth wire is longest for same reason so that the wire remains earthed so you dont get shocked.

 

[Bob.B]

https://www.checkatrade.com/blog/wp-content/uploads/2021/02/Plug-wiring-diagram.jpg

https://www.google.com/url?sa=i&url=https://www.cyberphysics.co.uk/topics/electricity/home/3pinplug.html&psig=AOvVaw3uHrpQeI02bFEKbJ78brnY&ust=1713875677275000&source=images&cd=vfe&opi=89978449&ved=0CBIQjRxqFwoTCJDXkcrq1YUDFQAAAAAdAAAAABBI

uk plugs are designed with several features

live wire brown is delibrately made shorter so if you accidentally pull out the plug to hard that the live wire is removed from power first.
earth wire is longest for same reason so that the wire remains earthed so you dont get shocked.

Thanks.

 

[Bob.B]

You must live in the USA like me. This seems to be a requirement for power cords in the UK. I was very surprised these are the old style glass tube fuses. The only thing I can think of is they are worried about the power cord itself starting on fire. The wires in the wall would be large enough that the circuit breaker would trip before they overload. The wires in a power cord though can be much smaller.

I have avoided this thread because I have know little about these cords. Maybe if there are different sizes of fuses in different cords maybe he got one from a device rated for lower power and accidentally swapped them.

Thanks.....I guess I live under a rock as I have never seen such a thing.

 

[beyondlogic]

You must live in the USA like me. This seems to be a requirement for power cords in the UK. I was very surprised these are the old style glass tube fuses. The only thing I can think of is they are worried about the power cord itself starting on fire. The wires in the wall would be large enough that the circuit breaker would trip before they overload. The wires in a power cord though can be much smaller.

I have avoided this thread because I have know little about these cords. Maybe if there are different sizes of fuses in different cords maybe he got one from a device rated for lower power and accidentally swapped them.

uk uses a ring circuit system
see below how it works
https://upload.wikimedia.org/wikipe.../Ring_circuit.svg/1024px-Ring_circuit.svg.png

the advantage of this system is you can have multiple high power appliances on at once without it causing balancing issues.

and because our voltage is much higher 230v all appliances have to be fused.

advantages of uk system is we can cut power to a socket by a switch in this circuit

practically all plugs can be serviced. the fuse protects the product and the cable 1 example would be if my pc got a massive spike or drawed to much current the fuse would blow and cut the power.

 

[beyondlogic]

Thanks.....I guess I live under a rock as I have never seen such a thing.

not that uncommon if im being honest alot of people i knew in usa where puzzled by uk plugs lol

 

[Satan-IR]

I think common fuses for plugs were 5A I think but that changed.

According to latest revisions of the electrical code the fuses in the plugs are 3A for appliaces up to 700W and 13A for appliances form 700W to 3KW consumption like washing machines, kettles, irons and such.

Although I think 5A fuses are still avilable and sold.

Common 'surge protectors (and usually ones on the cheaper side) just have a MOV (metal-oside varistor) inside between the live and neutral lines/connectors. These MOVs are voltage dependant and provide no pretection agains surge casued by inrush current or brown-outs.

OP's habit of flipping the socket/outlet switch with a foot :

It's not as precise, and there are times where I'll keep the switch in the middle for a few seconds, quickly flicking power on and off - I believe that happened when I turned it off last.

Might have caused a spike/spark or a sustained votage sag and as MOV-based surge protectors can't deal such conditions and that might cause the MOV to fail and the plug fuses go open circuit. IF the surge protector has always been between the socket/outlet and PC when OP tested with different fuse in different room too.

 

[O-451]

I can confirm that it was the 5A fuse in the PSU's plug that blown. And I've always used a surge protector with it, even when it blew the replacement fuse.

When I first noticed that my PC wasn't turning on, my monitors (which were both plugged into the surge protector) still powered on and went into standby, if that helps.

Truth be told upon getting in and looking at it, I don't know. I think I'm just going to RMA it and buy a new PSU - then pray that it's not an issue with my rig that'll just ah heck up PSUs.

 

[Satan-IR]

I would connect just the PSU to the wall and check if it runs without the surge protector and do the papwerlcip and multimeter tests. The problem might well be caused by a shorted MOV or other component/s shorting in the surge protector on the one outlet where you conenct the PSU. Others feeding monitors might be OK.

Take PSU out and do paperclip test or multimeter test on 3.3v, 5v and 12v rails outputs. There are a plethora of instructions and videos online as how to do it. It's not a difinitive answer as to whether the PSU can cope under transient and changing loads but a basic proof that it can turn on and output the voltages.

You'd need to dig out the PSU if you plan to RAM it anyway.

 

[Flayed]

You could change the fuse for a 13A one and see if it still blows

 

[Zerk2012]

You could change the fuse for a 13A one and see if it still blows

No don't do that!

 

[O-451]

I don't want to be a spoilsport but my heart's not really in it, sorry. I know the tests are safe but I don't feel comfortable prodding live connectors myself, and at the end of the day I don't see things going well if I plug everything back in to try again.

Be Quiet have accepted the invoice I provided them for an RMA and I'll go ahead with that. In the meantime I'll probably buy a new PSU and test it out with my components bit by bit - and if they send me a replacement I'll keep it as a backup.

I dug up an old SATA --> USB connector and connected my SSDs to my laptop - thankfully they're working fine, so I have some hope that the rest of my system isn't toast.

 

[Satan-IR]

You could change the fuse for a 13A one and see if it still blows

Yes he could but he shouldn't! That's practically what he needs to potentially cause an electrical fire.

There's something wrong with that wall socket > surge protector > PSU > PC circuit. Changing the fuse with something that allows an aditional 8A to go through is a recipe for disaster.