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dryja123
(@dryja123)
Honorable Member
Re: Power Supply failure


I am waiting on my Mk3 to ship. Would you suggest not using the Prusa power supply, and just go with the 350W supply from the get go.

Debra

Use the included PSU. More than 4000 orders have gone out the door and there may be 10 or so reported failure cases so far. That's a 1/4 of 1% failure rate.

You don't want to introduce more issues by not using the included parts to start. Prusa warranty and support is great if you have an issue down the road.

Posted : 16/02/2018 5:06 am
EC
 EC
(@ec)
Re: Power Supply failure

Eh. 10 people on this forum... maybe. There are other message boards and facebook group where the power supply issue is pretty common and a fairly big issue. I'd say it's definitely at lot more than you're letting on.

Posted : 16/02/2018 1:10 pm
jonathon.b
(@jonathon-b)
Estimable Member
Re: Power Supply failure

Having a briefly read of some of the comments on this thread, Do these problems mainly seem to be happening with US 110v supplied PSU's?

I'm in the UK so from what I looked at most of you seemed US based.

Something that gives me comfort is the printer comes with a CE marking, which should mean all parts comply with current European standards. I think that's why they enclose the terminals on the supply so its above IP2X rating.

If the power supplies are low quality the chances are they are not CE marked and could be a week point, but like someone else said with a low % failure rate its probably noting to be to concerned about

Posted : 16/02/2018 3:10 pm
Craig Trader
(@craig-trader-2)
Eminent Member
Re: Power Supply failure


Having a briefly read of some of the comments on this thread, Do these problems mainly seem to be happening with US 110v supplied PSU's?

I'm in the UK so from what I looked at most of you seemed US based.

Something that gives me comfort is the printer comes with a CE marking, which should mean all parts comply with current European standards. I think that's why they enclose the terminals on the supply so its above IP2X rating.

If the power supplies are low quality the chances are they are not CE marked and could be a week point, but like someone else said with a low % failure rate its probably noting to be to concerned about

1) Prusa Research is using the same power supply for all regions: the PSU auto-detects voltage and frequency. All you need is the correct mains cable for your local power.
2) Most of the complaints are from the US, because the largest fraction of the orders are from the US (43.3% -- see the unofficial order tracking spreadsheet).
3) The stock PSU is CE marked, but it's made in PRC ie: China, labeled in English and Czech.

I'm one of the unlucky few with a dead PSU. I went ahead and ordered a generic replacement from Amazon (which arrived damaged, and was the wrong size) then a Meanwell replacement, also from Amazon (which arrived in good shape). The Meanwell PSU is much larger than the stock PSU, and even with Paul's well-designed PSU cover and brace will not directly replace the stock PSU, because there's not enough slack in the wiring harness. At the moment, my Meanwell PSU is sitting to the left of my Mk3, while the brace is attached to the right-side to stabilize the upright frame. This solution works, but it isn't a permanent solution -- to keep using the Meanwell, I would need to replace the wiring harness.

It's obvious that Prusa Research had these power supplies custom manufactured -- I've looked at dozens of 24V supplies this week, and all of them are larger and heavier than the Prusa PSU. Generic 24V supplies all tend to be 115mm wide (vs 100mm for the Prusa PSU) because they have 3 sets of output terminals (instead of the 2 sets that the Prusa PSU provides).

Is the PSU failure rate higher than I'd like? Yes, obviously. Is it too high? That's a question for Prusa to answer. Does it take too long to get Prusa to ship out a replacement? At the moment, yes, because they're busier than a one-armed paper hanger, just trying to keep up with demand for their printers. On the other hand, once you get their attention, they will ship out a replacement -- mine should be here Monday.

I'm still very happy with my Mk3 Kit purchase -- the Mk3 is still a much better printer than the Mk2 (I have both).

I solve problems, usually with computers ......
Posted : 17/02/2018 12:13 am
Craig Trader
(@craig-trader-2)
Eminent Member
Re: Power Supply failure


I am waiting on my Mk3 to ship. Would you suggest not using the Prusa power supply, and just go with the 350W supply from the get go.

Use the stock PSU, definitely. The odds of a failure are very low, and the supplied wiring is designed for the stock PSU. Wiring up a replacement is non-trivial.

- Craig -

I solve problems, usually with computers ......
Posted : 17/02/2018 12:16 am
dryja123
(@dryja123)
Honorable Member
Re: Power Supply failure


Eh. 10 people on this forum... maybe. There are other message boards and facebook group where the power supply issue is pretty common and a fairly big issue. I'd say it's definitely at lot more than you're letting on.

I don't have a facebook account so I was speaking to what I've seen here. If you had to throw a number and guess how many failures do you think have been reported? 10, 50, 100, 1000?

I was just suggesting that the poster should use the PSU given to them unless they had an issue with it. Besides, more issues may be resolved with models that were shipped later.

Posted : 17/02/2018 3:01 am
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure



I am waiting on my Mk3 to ship. Would you suggest not using the Prusa power supply, and just go with the 350W supply from the get go.

Debra

Use the included PSU. More than 4000 orders have gone out the door and there may be 10 or so reported failure cases so far. That's a 1/4 of 1% failure rate.

You don't want to introduce more issues by not using the included parts to start. Prusa warranty and support is great if you have an issue down the road.

Your logic is a little flawed. First of all, not everyone hits up the forums when they have a problem, and I know a lot of people who simply don't use Facebook. It seems like every day now someone posts a PSU related failure on Facebook these days regardless, and it doesn't explain why me and a few other people have had more than one complete failure. The reality is, this is probably a $15 power supply including the very simple power panic module. That power panic module probably costs less than a couple dollars to Prusa. So I laugh when I see they are starting to sell the PSU on their site for a whopping $89.

Posted : 17/02/2018 7:09 am
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure



Having a briefly read of some of the comments on this thread, Do these problems mainly seem to be happening with US 110v supplied PSU's?

I'm in the UK so from what I looked at most of you seemed US based.

Something that gives me comfort is the printer comes with a CE marking, which should mean all parts comply with current European standards. I think that's why they enclose the terminals on the supply so its above IP2X rating.

If the power supplies are low quality the chances are they are not CE marked and could be a week point, but like someone else said with a low % failure rate its probably noting to be to concerned about

1) Prusa Research is using the same power supply for all regions: the PSU auto-detects voltage and frequency. All you need is the correct mains cable for your local power.
2) Most of the complaints are from the US, because the largest fraction of the orders are from the US (43.3% -- see the unofficial order tracking spreadsheet).
3) The stock PSU is CE marked, but it's made in PRC ie: China, labeled in English and Czech.

I'm one of the unlucky few with a dead PSU. I went ahead and ordered a generic replacement from Amazon (which arrived damaged, and was the wrong size) then a Meanwell replacement, also from Amazon (which arrived in good shape). The Meanwell PSU is much larger than the stock PSU, and even with Paul's well-designed PSU cover and brace will not directly replace the stock PSU, because there's not enough slack in the wiring harness. At the moment, my Meanwell PSU is sitting to the left of my Mk3, while the brace is attached to the right-side to stabilize the upright frame. This solution works, but it isn't a permanent solution -- to keep using the Meanwell, I would need to replace the wiring harness.

It's obvious that Prusa Research had these power supplies custom manufactured -- I've looked at dozens of 24V supplies this week, and all of them are larger and heavier than the Prusa PSU. Generic 24V supplies all tend to be 115mm wide (vs 100mm for the Prusa PSU) because they have 3 sets of output terminals (instead of the 2 sets that the Prusa PSU provides).

Is the PSU failure rate higher than I'd like? Yes, obviously. Is it too high? That's a question for Prusa to answer. Does it take too long to get Prusa to ship out a replacement? At the moment, yes, because they're busier than a one-armed paper hanger, just trying to keep up with demand for their printers. On the other hand, once you get their attention, they will ship out a replacement -- mine should be here Monday.

I'm still very happy with my Mk3 Kit purchase -- the Mk3 is still a much better printer than the Mk2 (I have both).

The wiring harness is simple. Go to your home improvement store and buy some 14-16 gauge power cord wire and buy some male and female spade connectors. Everything else is reusable.

Posted : 17/02/2018 7:14 am
dryja123
(@dryja123)
Honorable Member
Re: Power Supply failure



Your logic is a little flawed. First of all, not everyone hits up the forums when they have a problem, and I know a lot of people who simply don't use Facebook. It seems like every day now someone posts a PSU related failure on Facebook these days regardless, and it doesn't explain why me and a few other people have had more than one complete failure. The reality is, this is probably a $15 power supply including the very simple power panic module. That power panic module probably costs less than a couple dollars to Prusa. So I laugh when I see they are starting to sell the PSU on their site for a whopping $89.

I don't understand how my logic is flawed. I'm suggesting that the failure rate is low in comparison to how many printers have gone out the door. If my logic is flawed throw a number on how many you think are defective and do the math on against the approximate 4000 - 6000 orders that went out the door.

How is my logic flawed by suggesting to the poster to use stock parts so you don't introduce more problems. I didn't want to guess the posters skill level but what if this is their first ever printer and they ever built and they accident mix up polarity on and after market PSU and damage a printer or worse, kill themselves.

If you're suggesting that there's a 1% failure rate of 5% (200) 10% (400) then that would suggest there's a chronic issue.

And you're right about people who don't use Facebook, I'm one of them. I'm not sure if you intended to respond to Eric's message but you didn't quote him.

Eh. 10 people on this forum... maybe. There are other message boards and facebook group where the power supply issue is pretty common and a fairly big issue. I'd say it's definitely at lot more than you're letting on.

Posted : 17/02/2018 3:22 pm
Protoncek
(@protoncek)
Reputable Member
Re: Power Supply failure

OK, in my opinion you're right about failure rate, i think it's not critical - if it would be that Prusa would change PSU type weeks ago.
However i don't see any harm using any ohter PSU rated at 24V 240VA or more. 24V is 24V, no matter if PSU is original or any other kind. Polarity reversal can be mixed on original or any other PSU for that matter. And this kind of fault isn't included in warranty no matter which PSU you will use. Kit is intended for people with basic knowledge, not for total dumbs (if i may exaggerate a bit 😉 )
If i've had two consequent PSU failures be sure that third one wouldn't be original but some know brand and somewhat more powerfull.

Posted : 17/02/2018 3:42 pm
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure




Your logic is a little flawed. First of all, not everyone hits up the forums when they have a problem, and I know a lot of people who simply don't use Facebook. It seems like every day now someone posts a PSU related failure on Facebook these days regardless, and it doesn't explain why me and a few other people have had more than one complete failure. The reality is, this is probably a $15 power supply including the very simple power panic module. That power panic module probably costs less than a couple dollars to Prusa. So I laugh when I see they are starting to sell the PSU on their site for a whopping $89.

I don't understand how my logic is flawed. I'm suggesting that the failure rate is low in comparison to how many printers have gone out the door. If my logic is flawed throw a number on how many you think are defective and do the math on against the approximate 4000 - 6000 orders that went out the door.

How is my logic flawed by suggesting to the poster to use stock parts so you don't introduce more problems. I didn't want to guess the posters skill level but what if this is their first ever printer and they ever built and they accident mix up polarity on and after market PSU and damage a printer or worse, kill themselves.

If you're suggesting that there's a 1% failure rate of 5% (200) 10% (400) then that would suggest there's a chronic issue.

And you're right about people who don't use Facebook, I'm one of them. I'm not sure if you intended to respond to Eric's message but you didn't quote him.

Eh. 10 people on this forum... maybe. There are other message boards and facebook group where the power supply issue is pretty common and a fairly big issue. I'd say it's definitely at lot more than you're letting on.


Use the included PSU. More than 4000 orders have gone out the door and there may be 10 or so reported failure cases so far. That's a 1/4 of 1% failure rate.


My point is you can't imply that there have only been 10 failures. The data isn't there to make the claim that 1/4 of 1% is the actual failure rate when you're basing your numbers only on people raising their voice in this forum. Personally I do believe this is more widespread than that, but only Prusa knows the actual numbers. I'm concerned about the longevity of this power supply in general. What's the failure rate after 6 months of printing for example?

Posted : 17/02/2018 4:04 pm
The Plastic Shed
(@the-plastic-shed)
Estimable Member
Re: Power Supply failure

For now I'm taking Jo's word for it that they did their research, I am however sceptical because basic math confirms that the 240W rating is borderline, with everything working together the components are more than capable of pulling this amount of power. The Einsy recommendation is for 16A+ minimum whilst the installed PSU is only 10A - again this isn't guesswork https://ultimachine.com/products/einsy-rambo-1-1 - hence I am and shall remain sceptical although mine has performed OK so far - currently on 11 days 6 hours 44 minutes, most of which doing PETG (although I use Rigid ink that prints cooler than most). At a professional level I wouldn't approve the current sizing, I'd want at least another 25 to 50% over and above what the maximum ever possible current was since you don't want to be on the red line all the time - preferably never if you want longevity.

Most Chinese PSU's seem biased toward 120 and 220 but should have a tolerance, what isn't stated is any derating requirement and most switched mode power supplies must be derated especially at lower voltages i.e. below 115 VAC. Like it or not unless Jo had a hand in component specification the items used in Chinese PSU's can vary in quality massively, not all components are born equal - ask anyone in the electronics game, again this is not speculation.

Then you have the constant switching clearly heard when the capacitors charge and discharge trying to keep things stable as the heated bed switches, the inrush this causes can deliver all kinds of stress to upstream components.

There simply isn't the evidence for any black and white conclusions but there is enough to make one suspicious. I have a spare Cosel but I won't use it unless I need to, for what the Mk3 cost there are certain expectations and obligations - if there weren't I'd have bought a cheapo Chinese - I bought into Jo's passion and reputation, so far I haven't been disappointed with that choice.

Posted : 17/02/2018 4:54 pm
dryja123
(@dryja123)
Honorable Member
Re: Power Supply failure



My point is you can't imply that there have only been 10 failures. The data isn't there to make the claim that 1/4 of 1% is the actual failure rate when you're basing your numbers only on people raising their voice in this forum. Personally I do believe this is more widespread than that, but only Prusa knows the actual numbers. I'm concerned about the longevity of this power supply in general. What's the failure rate after 6 months of printing for example?

Let me share some more of my flawed logic. When people invest money into a product and something fails they tend to look for an outlet to vent. People vent on forums, blogs, YouTube videos, etc... The forums is the only place I've seen people report defective PSUs but I admit that I'm not on Facebook.

Once again, 10 or so is a loose implication and I was speculating the reported defectives I've seen here. I understand that this support forum is not the authority on the data. You disregarded my overall point, however. Do you agree or disagree with suggesting to the poster that they should use or not use the included PSU. That was the overall point.

Posted : 17/02/2018 5:02 pm
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure


10 or so is a loose implication and I was speculating the reported defectives I've seen here. I understand that this support forum is not the authority on the data. You disregarded my overall point, however. Do you agree or disagree with suggesting to the poster that they should use or not use the included PSU. That was the overall point.

To answer your question, that's a tough one. I'm nervous to use my 3rd replacement, because my second PSU didn't silently fail like the first. It arced like crazy, and literally exploded a component. That makes me nervous, because there are a couple people on this thread that failed in the same fashion. I'll probably use my third one though to be honest. I've always been a risk taker lol.

Posted : 17/02/2018 6:52 pm
michael.a35
(@michael-a35)
Trusted Member
Re: Power Supply failure

Do we have any more recent hypothesis from Prusa? This problems seems to be continuing.

I don’t mind, because I know Prusa is trustworthy and has great replacement policy, but everywhere I look electrical engineers say PSU clicking is very bad.

Posted : 17/02/2018 6:57 pm
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure


Do we have any more recent hypothesis from Prusa? This problems seems to be continuing.

I don’t mind, because I know Prusa is trustworthy and has great replacement policy, but everywhere I look electrical engineers say PSU clicking is very bad.

According to Prusa the clicking is not a hazard, it's just the PWM chip cycling on and off as the heat bed demands less power once it gets close to temperature. My guess is that since all these PSUs seem to be failing in the same fashion, that it's the same part shorting out. Problem is I don't know what part that is. It seems to be happening on the AC side of the PSU, that part is obvious. Maybe it's overheating causing the insulated wire on one of the transformers to melt. Pure speculation though.

Posted : 17/02/2018 7:07 pm
dryja123
(@dryja123)
Honorable Member
Re: Power Supply failure


To answer your question, that's a tough one. I'm nervous to use my 3rd replacement, because my second PSU didn't silently fail like the first. It arced like crazy, and literally exploded a component. That makes me nervous, because there are a couple people on this thread that failed in the same fashion. I'll probably use my third one though to be honest. I've always been a risk taker lol.

I completely understand and to be fair, if you take a look at my comments on the very first page of the thread you'll see why the PSU scares me too. I actually cancelled my MK3 order over it but eventually switched it back when I realized that the defective rate is minimal. I understand why you're hesitant to try a third because you've had 2 failures but that's unfortunate and not the norm. It sucks that it happened to you and I pray the same doesn't happen to me.

Posted : 17/02/2018 7:16 pm
michael.a35
(@michael-a35)
Trusted Member
Re: Power Supply failure



Do we have any more recent hypothesis from Prusa? This problems seems to be continuing.

I don’t mind, because I know Prusa is trustworthy and has great replacement policy, but everywhere I look electrical engineers say PSU clicking is very bad.

According to Prusa the clicking is not a hazard, it's just the PWM chip cycling on and off as the heat bed demands less power once it gets close to temperature. My guess is that since all these PSUs seem to be failing in the same fashion, that it's the same part shorting out. Problem is I don't know what part that is. It seems to be happening on the AC side of the PSU, that part is obvious. Maybe it's overheating causing the insulated wire on one of the transformers to melt. Pure speculation though.

The pulse modulation seems an odd reason. The PWM rate would be nowhere near the frequency of the clicking form what I’ve heard. I’ll let them do their thing though.

I have an MIT engineer friend. If mine fails when it comes maybe I can show him and help everyone out.

Posted : 17/02/2018 9:36 pm
Christopher Tilley
(@christopher-tilley)
Trusted Member
Re: Power Supply failure



The pulse modulation seems an odd reason. The PWM rate would be nowhere near the frequency of the clicking form what I’ve heard. I’ll let them do their thing though.

I have an MIT engineer friend. If mine fails when it comes maybe I can show him and help everyone out.

The clicking occurs with the indicator light on the heated bed. I'd guess it's like 5 to 10 hz. The light stays solid for a couple minutes during the initial heating, then as the bed approaches the set temperature, cycles on and off. The pulses coincide with the clicking.

This is how josef explains it:

"Some users reported PSU “clicking”. What happens is, when you switch to high load on the heated bed the input coil winding vibrate a little. It is physics. The fact this new PSU has active PFC may make this more pronounced, especially on 110V. But you can hear it with every PSU on both 120V and 230V when you stick your ear close enough. As we are preparing to integrate our whole PSU + PowerPanic + connector assembly into one unit – to reduce the assembly time, we have a power supply specialist in-house. So we could quickly find out that this is what is going on. They are perfectly safe and they were also tested when we were getting them tested for the CE marking at the external lab. The clicking can be reduced by increasing the PWM frequency for the heatbed in the later firmware, which we plan to implement."

Posted : 17/02/2018 11:22 pm
Protoncek
(@protoncek)
Reputable Member
Re: Power Supply failure

OK, i agree that it's physics. But i also know that this physics can be silenced. That's why some coils are submerged in resin to eliminate clicks. Better / more precise manufacturing and better quality core materials also causes clicks to go away. But having more expensive PSU would increase total cost of printer.

Posted : 18/02/2018 9:57 am
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