Power Supply failure  

Re: Power Supply failure

I'm going to post a factual summary here in hopes that it kills this thread.
...

Nice writeup. But those are not facts. I could go over each line and disprove it but it's much easier if you would agree that you just posted static specs. And I think most of us would agree, that by the specs it works.
What you're not writing is that the specs are pretty tight set. There is no room for tolerances. For example you can measure 10x MK42 beds and 10x 40W heat elements and you will get a nice range of readings. Usually around 5-10% for resistors.
Now let's just assume your provided measure of 215 watts @ 120V is a value by the specs like most your calculated values. 10% more would mean 236.5W. It's already pretty close to the max rated 240W.

Now we can go to the next step and add the heat (because it's close to the bed and extruder cooling fan is blowing towards the PSU). The voltage below 120V is also pretty common in USA. And the PWM heating which is stressing the PSU a lot. It's just very high risk that this PSU can't survive very long under this conditions. For some people it's happening under warranty, for others it's not.

There is no reason to kill this thread. It shows pretty nice picture what we are encountering here in US with the provided power supplies. It's not about "cheap" PSU, it's just under powered for the usage in USA.

Re: Power Supply failure

Nice writeup.

It's not about "cheap" PSU, it's just under powered for the usage in USA.

Thanks but the PSU is absolutely not underpowered for usage in the USA, this is unsupported speculation perpetuated by the misinformation throughout this thread: The AC input is rated for 10A regardless of input voltage, the DC volts don't change when you run the input at a different wall voltage.

Fact: Prusa sells 5K+ MK3's a month for over a year with zero major hardware revisions, and can still barely keep up with demand.

This alone demonstrates that there is clearly no systematic issue with the MK3 Power Supply, or they would have altered the design - they change things all the time, so where's the outrage?

Power supplies go bad, this thread has lumbered on for a year with no direction, it's unproductive dog-piling about a non-issue.

My post is to provide factual clarity on the issue, if you have some facts to contribute, please do.

Re: 'static specs'. I personally measured several 24V 40W E3D heaters we have for spares and two MK52 beds we've got in the shop, and I'm being very generous with my numbers.

Besides, if the stuff attached was somehow way out of spec, it would blow the Einsy fuse first...not the PSU fuse.

Do the math yourself - measure the system yourself - don't take my word for it.

Re: Power Supply failure

Well, you're completely off regarding clicking and buzzing part. What you wrote goes for old (ancient) or poorly designed PSU's, not for new ones or, in our case, PSU which costs almost 100 euros. I would agree that cheap chinese PSU for 20-30$ would hiss and rattle, but not one for 100$ (BTW... the price of PSU after warranty is far from "not expensive"). These days (good) PSU's mostly run at high frequencies, which eliminates any noise. If PSU clicks that surely means that cheap parts are installed in it. Ferrite chokes do ratlle, but again, not quality ones.
We alreadey came to a conclusion that power 240W is quite enough, since PSU's don't die in Europe...

I agree, components do die, but don't you think that if they die too often and only in USA then it must be something wrong with design regarding powering them to 110V...? Are you trying to say that two dead PSu's in 6 months is "quite OK" for you? Come on...

And, lastly... why on earth would you want to "kill this thread"?

You are correct that all current PSUs supplied by Prusa's don't "buzz" from loose chokes, only our "old boy". I post that to make the info comprehensive, it's the exact same PSU that has always been supplied with the MK3 - but frankly they may just be "shaking them" as part of the QA process inside Prusa to weed out the "buzzy" ones - it's not really a design change, just an extra manufacturing or QA step.

If you do the math assuming Prusa posts accurate numbers, there are *maybe* 50 people in this ENTIRE thread of 58 pages with dead supplies over the course of a year, let's be super generous and say that's 5 posts a month, actually let's say the posts account for 10% of the actual failures that get reported so let's call it 50 PSUs are dead every month, out of 5000...so if their failure rate is speculatively 1 in 100 at the high-end?

I'd guess it's way below 1%, and you can be sure they track it much better on their own back-end of user-reported failures and RMA "shrinkage" rather than scoping this community forum.

This thread has no productive value, it only precipitates confusion.

Re: Power Supply failure

Well, you can't know how many people experienced dead PSU and never posted here, or they are not even members of this forum. Unless, of course, you are employed in Prusa or PSU's manufacturer. For instance: my filament sensor died a week or two ago. I've got a replacement for free, but i didn't post this event anywhere...

Regarding "underpowered": i assume you're not pure electronics guy, right? I mean - you don't do hobby projects, solder stuff, program MCU's... it clearly shows that. Just an example: you can take mosfet with specs of 10A max and run it at 9 amps, or you can take 20A mosfet and still run it at 9 amps. Fisrt one will be at 90%+ all the time while second one will be onl at moderate 50%. Of course, second one is more expensive, but you don't need a degree to know that second one will live waaaay longer than first one. And i bet that this is exactly what is happening in these PSU's.

The pure fact in electronics (golden rule) is: NEVER run anything at it's maximum for long. And NEVER even design things that will do that. This is fist golden rule of a good design of any electronics. A good practice is 50-70% max. That's why Prusa should ship printers with appr. 300VA PSU's, not 240 ones. The fact you can't deny is that printer is already DESIGNED to run certain time at it's limit. A big mistake.

Re: Power Supply failure

I am very happy. They shipped my my power supply in a week. I am back up and running.

I boiught a Meanwell 350/24 as bac up.

Re: Power Supply failure

Nice writeup.

It's not about "cheap" PSU, it's just under powered for the usage in USA.

Thanks but the PSU is absolutely not underpowered for usage in the USA, this is unsupported speculation perpetuated by the misinformation throughout this thread: The AC input is rated for 10A regardless of input voltage, the DC volts don't change when you run the input at a different wall voltage.

Fact: Prusa sells 5K+ MK3's a month for over a year with zero major hardware revisions, and can still barely keep up with demand.

This alone demonstrates that there is clearly no systematic issue with the MK3 Power Supply, or they would have altered the design - they change things all the time, so where's the outrage?

Power supplies go bad, this thread has lumbered on for a year with no direction, it's unproductive dog-piling about a non-issue.

My post is to provide factual clarity on the issue, if you have some facts to contribute, please do.

Re: 'static specs'. I personally measured several 24V 40W E3D heaters we have for spares and two MK52 beds we've got in the shop, and I'm being very generous with my numbers.

Besides, if the stuff attached was somehow way out of spec, it would blow the Einsy fuse first...not the PSU fuse.

Do the math yourself - measure the system yourself - don't take my word for it.

It seems like you want to fire up this thread again...
Of course is my statement pure assumption based on the reports on this issue I saw this year. I don't want to debate with you about the numbers. Most of the measurements were done already by many different people with an engineering degree. My MK3 is working fine for 8 month now, so any measurements on my unit are not helpful.

This thread is helping us to understand when it happens and under which conditions. Calling it "no issue" and closing this communication channel doesn't help anybody.

Maybe you can explain following cases which are bothering me most:
-> Using MW-350-24V eliminates any clicking noise.
-> We have reports of people where their PSU has failed more than two times after a short period of time. They replaced it to MW-350-24V and this PSU didn't fail again.

For me personally it helped to see that it is operating at around 80%-90% load even on perfect unit. This is not good especially for a PSU which is being treated rough (with heat and PWM). That's why I will not replace my PSU if it fails out of warranty with the original one. I would buy one with more headroom.

Re: Power Supply failure

Well, you can't know how many people experienced dead PSU and never posted here, or they are not even members of this forum. Unless, of course, you are employed in Prusa or PSU's manufacturer. For instance: my filament sensor died a week or two ago. I've got a replacement for free, but i didn't post this event anywhere...

Takeaway: Prusa will replace failed components under warranty if you contact their support.

I am very happy. They shipped my my power supply in a week. I am back up and running.

I boiught a Meanwell 350/24 as bac up.

Takeaway, Prusa has replaced components under warranty when you contact their support; posting in this forum has caused people without problems to buy things they don't need because they believe they've purchased a product prone to failure.

Of course is my statement pure assumption based on the reports on this issue I saw this year. I don't want to debate with you about the numbers. Most of the measurements were done already by many different people with an engineering degree. My MK3 is working fine for 8 month now, so any measurements on my unit are not helpful.

This thread is helping us to understand when it happens and under which conditions. Calling it "no issue" and closing this communication channel doesn't help anybody.

Maybe you can explain following cases which are bothering me most:
-> Using MW-350-24V eliminates any clicking noise.
-> We have reports of people where their PSU has failed more than two times after a short period of time. They replaced it to MW-350-24V and this PSU didn't fail again.

Someone who has killed more than one PSU in a row is more likely to have some kind of severe supply issue that is killing PSUs, like input surges; or I guess you think this is a common occurrence and it's been swept under the rug? (Unlikely)

MW-350-24V is a completely different topology - a charger doesn't sound like a mustang, they are different beasts. The clicking comes from the power supply, so yes, changing the power supply would eliminate the clicking, assuming you could still hear it over that loud active fan.

As to replacing with a larger supply... I went with the LRS-350-24 and, at least for me, it is a much noisier/louder power supply. When the cooling fan kicks in, it pretty much drowns out the rest of the printer. When idle, the switching noise is noticeably louder than it was on the Prusa supply. It's not annoying or anything and you can't hear it unless you are near the printer, but it is definitely there.

This is "dragon chasing" that wastes productive time: replacing PSU becasue Prusa doesn't know how to design a 3D printer (as if), oh no, the non-OEM PSU doesn't fit so let's redesign parts and design a bracket to the machine to make it "better", oh no the fan is loud now let's mod the PSU and swap with a quieter fan; and while I'm at it go to home depot and get some lamp cord to re-wire my panic circuit...

It's not an issue to refit a stronger PSU onto your Prusa, but it's absolutely not necessary. I've repaired my fair share of Meanwell supplies to know they're nothing special.

Re: Power Supply failure

Someone who has killed more than one PSU in a row is more likely to have some kind of severe supply issue that is killing PSUs, like input surges; or I guess you think this is a common occurrence and it's been swept under the rug? (Unlikely)

MW-350-24V is a completely different topology - a charger doesn't sound like a mustang, they are different beasts. The clicking comes from the power supply, so yes, changing the power supply would eliminate the clicking, assuming you could still hear it over that loud active fan.

It happened more than once. It doesn't matter what kind of supply issues this guys might have. All the other electronic stuff in their room is working fine and bigger PSU is solving their issue. From the customer perspective I fully understand the complains.

And if you really start with car metaphors.... You can tow couple tons with your Prius or get a RAM truck. That's exactly how it sounds to me.

Re: Power Supply failure

posting in this forum has caused people without problems to buy things they don't need because they believe they've purchased a product prone to failure.

People without problems? With, say, two PSU's dead in 6 months? Yeah ,sure... people WITHOUT problems indeed.

Someone who has killed more than one PSU in a row is more likely to have some kind of severe supply issue that is killing PSUs, like input surges;

Yeah, sure. And interesting - because of that "power surges" of yours only Prusa PSU's die, and nothing else, right? And even more... quite some people has obvioulsy exactly the same type of these "power surges" which kill only and only Prusa PSU's...
Come, on...even you don't believe in what you write... PSU MUST BE made such way that IT CAN SURVIVE those surges.

As i said before: you comment on thing you don't know inside and your statement that PSU is not underpowered just confirms that. PSU CAN NEVER work at it's 100%. Max. power is reserved for EMERGENCY ONLY and for short periods. Designing ANY machine to do so is WRONG practice!!!! Period.

It's like i would comment on repairing cars, but i'm not a mechanic...

Re: Power Supply failure

posting in this forum has caused people without problems to buy things they don't need because they believe they've purchased a product prone to failure.

People without problems? With, say, two PSU's dead in 6 months? Yeah ,sure... people WITHOUT problems indeed.

They bought a Meanwell power supply based on speculation the OEM PSU is prone to fail, an unfounded "rumor" perpetuated by this thread.

Someone who has killed more than one PSU in a row is more likely to have some kind of severe supply issue that is killing PSUs, like input surges;

Yeah, sure. And interesting - because of that "power surges" of yours only Prusa PSU's die, and nothing else, right? And even more... quite some people has obvioulsy exactly the same type of these "power surges" which kill only and only Prusa PSU's...
Come, on...even you don't believe in what you write... PSU MUST BE made such way that IT CAN SURVIVE those surges.

As i said before: you comment on thing you don't know inside and your statement that PSU is not underpowered just confirms that. PSU CAN NEVER work at it's 100%. Max. power is reserved for EMERGENCY ONLY and for short periods. Designing ANY machine to do so is WRONG practice!!!! Period.

It's like i would comment on repairing cars, but i'm not a mechanic...

An input surge will blow the AC Fuse in the IEC inlet, not kill the PSU; if it's a faulty PSU it will eventually die regardless of load.

Repeated blowing of AC fuse may indicate a 120V issue, or a failing PSU, it's a troubleshooting step, not a solution.

You're convoluting a few random reports as some systematic issue with the PSU, which is demonstrably not true.

PR tests all PSUs under load twice before shipping.

Out of the all the MK3's we've touched I've seen one dead PSU, and it was a shipping problem, the mains cap got completely dislodged from the board taking the traces with it.

POWER SUPPLIES FAIL for numerous reasons, this thread has not demonstrated any noteworthy or common failure mode, in the rare case that it fails under warranty Prusa Support will take care of it, that's the bottom line.

Re: Power Supply failure

Which mean well power supply did you buy?

Re: Power Supply failure

I had two OEM PSUs fail within 3 months after assembly. They (Prusa Support) weren't receptive to replacing the second one either, so I replaced it with the Meanwell. It has been going strong for a couple months. 4 other 3d printers are in the room on the same UPS and the only two PSU failures have been on the lone MK3.

Re: Power Supply failure

I had two OEM PSUs fail within 3 months after assembly. They (Prusa Support) weren't receptive to replacing the second one either, so I replaced it with the Meanwell. It has been going strong for a couple months. 4 other 3d printers are in the room on the same UPS and the only two PSU failures have been on the lone MK3.

Odd. Once I answered 5-6 questions and sent photos, they repalce it.

Re: Power Supply failure

... this thread has not demonstrated any noteworthy or common failure mode...

Wrong again. This thread CLEARLY showed that common failure mode is powering it from US 120V supply. None of EU PSU's died.

But... i'm confused. I wish you would at least read your own posts and check out what you write, since you negate your own words. First you wrote:
Someone who has killed more than one PSU in a row is more likely to have some kind of severe supply issue that is killing PSUs, like input surges;

but now negate yourself:
An input surge will blow the AC Fuse in the IEC inlet, not kill the PSU

Come on.... decide already... WILL or WON'T kill the PSU?

It's no use anway. I give up. It's like talking to a brick wall. You won.

Re: Power Supply failure

It seams the Power supply Issue has bitten me as well. I walked out of my print room to grab some lunch and when I came back, the printer was off and stopped. Toggling the power switch had no affect. My battery back up was on and supplied power. Plugged it into the wall direct and still no power.

My only question is how to set my multi meter and what readings should I be getting?

I'm pretty new to multi-meters and haven't found a good source to help me fully grasp what everything means yet.

Re: Power Supply failure

It seams the Power supply Issue has bitten me as well. I walked out of my print room to grab some lunch and when I came back, the printer was off and stopped. Toggling the power switch had no affect. My battery back up was on and supplied power. Plugged it into the wall direct and still no power.

My only question is how to set my multi meter and what readings should I be getting?

I'm pretty new to multi-meters and haven't found a good source to help me fully grasp what everything means yet.

I was getting 0.7V with is way too little.

Re: Power Supply failure

I'm pretty new to multi-meters and haven't found a good source to help me fully grasp what everything means yet.

If you're inside a warranty, please contact support team and get it replaced. They will also guide you, if they need any additional checks.
If you're outside, get a mean well PSU like all of us and replace the original one.

Re: Power Supply failure

I'm pretty new to multi-meters and haven't found a good source to help me fully grasp what everything means yet.

If you're inside a warranty, please contact support team and get it replaced. They will also guide you, if they need any additional checks.
If you're outside, get a mean well PSU like all of us and replace the original one.

I started reading on Tab one, I just found out that there are fuses inside the PSU that are user replaceable. I e-mailed support but in the mean time I'll check on the fuses and hope for a positive outcome. Thanks for the input.

Re: Power Supply failure

I started reading on Tab one, I just found out that there are fuses inside the PSU that are user replaceable. I e-mailed support but in the mean time I'll check on the fuses and hope for a positive outcome. Thanks for the input.

There are two. One in the plug accessible outside and one is inside. I haven't seen a post here which was saying a fuse replacement helped. Usually after you replace a fuse, the PSU will blow up pretty nice because the fuse is blown for a reason. Contact Support via live chat. Sending email to support wasn't successful to me so far. Nobody answered to my emails but on live chat you get somebody on a line pretty fast.

Re: Power Supply failure

Adam, regarding multimeter: for line measurements set it to ACV. If it's autorange then this is it, if not set it to 200V. Your line voltage should be , i guess, around 120V.
For PSU output measurement set it to DCV and range (again if not autorange) anything above 25V. Output (red and black wires) should read 24V or slightly above.
You can check fuses with ohmmeter, set it to beep (beep when short-circuit probes) and check out: a good fuse should beep. You can usually see if it's ok or not: a good fuse has a tiny wire across glass tube. BUT PULL THE LINE OUT PLUG FIRST before you dissasemble PSU! And bear in mind that (good) PSU's have capacitor inside which can still be charged up to couple of hundred volts and can give you a pretty nasty shock, so it's better to wait a minute or two after disconnecting mains to be sure. However, since your is dead i doubt that capacitor will have any charge. Still, it's no harm to watch out.

Howerer, as nikolai said, i don't think that replacing fuse will help. Fuse is always "a secondary" element - first to blow is usually any semiconductor inside - there is no as fast fuse as transistor 🙁 Fuse is there not to protect circuit from dying but to protect from further damage of even fire.