Thank you for the reply and reassurance. You don't think it could be an issue at all just to leave the socket as is? I have another thread with more pictures, cause I noticed the other pins also have some marks on them too:
No I'm not smoking at all, as for parts if you meant my other componets:
I do notice when plugging it in it makes a slight crackling noise, but not while moving it while already plugged in
Don't move it around while plugged in, THAT will damage the socket potentially. Plug it in, leave it plugged in.
How about the pins themselves though? Those brown marks? If it's burnt, it won't cause problems right?
More than I should probably, it's my first build and I've had to work on it a few times. If you think it's fine I'll leave it alone. I do got some 99% Isopropyl, but no point in doing it if it's unnecessary. Thank you
Not a good idea.
I definitely won't be plugging in that way again then haha. Never knew that!Not a good idea.
When you connect the AC mains supply to an ATX PSU and the switch on the rear panel is set to On, a very high short-duration current flows into the PSU. Typically this current is in the range 40 to 100A AC.
In the example below, the current spike is 78.580A @ 115V AC and 93.990A @ 230V AC. This initial current surge charges the 400V DC bulk electrolytic in the PSU.
https://www.tomshardware.com/reviews/asus-tuf-gaming-550w-bronze-power-supply-review/2
"Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current of a PSU, right as it is turned on, the better."
When you plug the mains lead into the PSU an arc forms across the plug/socket interface and causes the scorch marks visible in your PSU plug. Stop doing it!
Leave the AC mains lead permanently plugged into the ATX PSU, or make sure the power is switched off at the wall before connecting the mains lead.
N.B. If you toggle the mains on/off switch on the back of an ATX PSU too many times (many 1000's of operations) you risk burning out the switch due to internal arcing across the switch contacts.
A friend came round with a dead mains switch in his PSU. He turns his computer on/off at the back 4 or 5 times a day and after 6 years he'd killed the switch. It was a cheap PSU so not surprising.
I've burnt out mains switches in cheap 13A (UK) mains sockets after 2 years of isolating computer PSUs. With multiple systems, the phantom/vampire power costs builds up so I power them down completely. When you flick the 13A switch back on, you get a current spike into the PSU.
As an electronics design engineer, I really should find a better solution, but for now, I'm using good quality 13A mains socket switches to power off my PCs and servers at night. 13A sockets are much cheaper to replace than a good quality ATX PSU.
I also just noticed while looking at the close up images that the middle prong almost looks a little chipped? I don't know if it's a trick of the light or what, but would that also be safe to leave alone?
Ah okay, I just wasn't sure lol. It's under 10 year warranty and considered a good PSU (rm750x) so if any issues arise I'll just RMA it. Only had it for almost 2 months but I have been plugging it in and out frequently, so I suppose it's normal. Just wanted to make sure it wasn't a fire hazard or anything
The "middle prong" is the mains safety Earth pin.
It should be OK, but if you have a spare mains lead, use it instead of the one you've been plugging and unplugging for 2 years. The spring contacts inside may be showing signs of wear and more importantly, pitting, due to repeated arcing at high currents.
Clean the carbon buildup. It causes resistance in the line voltage. Then seat ALL plugs and connectors well.
Cable isn't warm so it's probably fine. Not gonna bother with it right now. I don't want to damage it further or possibly electrocute myself wiping the pins off lol. If it's not warm there's not much resistance, right? That's at least what I've researched. I'm no professional though
After further inspection I don't believe it's a chip, just the way the scorch marks look. I'm asking you this because I'm getting conflicting information. Some people tell me it could cause resistance and I need to clean it, while others tell me it's fine to leave alone. I don't want to mess with it under fear of messing it up further, unless I have to.The "middle prong" is the mains safety Earth pin.
Under normal conditions, hardly any current flows through the Earth pin. All you'll see if you measure the current is a few milliAmps from the Class Y capacitors.
In the event of a serious fault inside the PSU, e.g. if the Line input (115V or 230V AC) shorts out to chassis, a large current (10's of Amps) will flow down to ground and blow a fuse or trip a breaker. That's why you should always use an ATX PSU with a good solid earth. With no safety earth, you might die from electrocution if a fault occurs.
It should be OK, but if you have a spare mains lead, use it instead of the one you've been plugging and unplugging for 2 years. The spring contacts inside may be showing signs of wear and more importantly, pitting, due to repeated arcing at high currents.
A new IEC mains lead should cost less than $10.
https://www.amazon.com/Monitor-Power-Cord-Replacement-6ft/dp/B09N3KRMXY
All connector pairs (plug/socket) are rated for a limited number of insertions. Some are rated for 1000's of operations, others only a few. On some Milspec components (microD) this limit is 50. After that, the gold plating starts to wear and contact pressure goes down. In critical applications, observing this limit is important.
So now I'm not even sure it's scorch marks anymore. I thought they were because they're very brown and dark in person, but could it genuinely just be wear marks from plugging it in and out often? I've never had the PC trip a breaker or anything since using it.I'd simply change the mains lead. You've no idea what damage has occurred inside. I regard IEC leads as expendable items and I've got loads of spares. Get a new lead. For peace of mind, clean the contacts in the PSU to reveal shiny metal. If you're tempted to use a file, don't leave any metal dust behind. Clean thoroughly.
The two shorter "prongs" in the PSU (the engineering term is 'pins' or 'contacts') are for Line and Neutral. If they are badly pitted and blackened due to arcing, they need attention. I've seen far worse damage inside cheap mains on/off switches, where half the metal contacts have vanished (vapourised).
The guy on Reddit is correct. The ground "prong" should never arc, unless the PSU has gone badly wrong, the Line input shorts out to the metal case and a fault current flows down to earth. This fault current is usually high enough to blow a mains fuse or trip a circuit breaker.
Very small currents (less than 2.5mA) flow down to ground through the earth pin, due to leakage currents in the Class-Y RFI filter capacitors inside the PSU. This is by design. A milliAmp is one thousandth of an Amp. The pitting of the Line and Neutral pins is due to currents of roughly 60A (60,000mA).
Any marks you see on the Earth pin are probably down to normal contact wear, but scorch marks will occur on the two shorter pins due to arcing, if you plug and unplug "live". As for high contact resistance, yes it can cause arcing which in extreme caaes can cause a fire.
You'll get conflicting advice because people have different opinions, especially on an open forum. I'm an electrical and electronics design engineer. Other people have only your safety in mind and may recommend caution. Some lay folk are well-meaning but mis-informed. Make up your own mind.
It's easy to misinterpret photos, but yours seem pretty clear to me. If it doesn't fizz and crackle with a new mains lead, I'd be happy to continue using it.
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