Power Supply failure  

Re: Power Supply failure

I ended up ordering and installing the LRS-350-24. It doesn't seem very loud at all even when the bed and hotend are heating up. I have printed about 24 hours worth of machine time with ASA and all is well so far.

I am hoping this will be my last power supply for the Prusa. This is a production machine dedicated to fab parts for manufacturing and engineering prototypes. It definitely prints better quality then the 4 cr-10s in the lab, but it hasn't proven as reliable so far.

Re: Power Supply failure

+1 victim of PSU issue here. i3 MK3 printing PETG for about 5-10 hours per day for 2 weeks. I'm in the USA, 120 VAC 60Hz. Based on what people have been saying online I just got a LRS-350-24 overnighted. Let's see how it goes.

MW NES - 350 - 24 and Power Supply failure

Hello,

I just finished jury rigging a Meanwell NES-350-24 power supply I scrounged from another project to the inputs of the EINSY RAMBO. When I figure out the power supply issues with my i3 MK3, it needs to go back to the original project, but so far it has taken me half way through the same print job that killed the PRUSA supplied PRPZ-24-240 in about 10 minutes, it has worked well for 3 of the 6 hours in he print job.

I thought someone might want to know that.

Mike

Re: Power Supply failure

My LRS-350-24 has been doing great for 3 weeks of heavy use now. I never heard anything back from support regarding the second stock power supply that went bad in 3 weeks.

Re: Power Supply failure

I'm going to order an LRS-350-24 for mine; which terminals am I supposed to use?

Re: Power Supply failure

All three + and all three - are common, so you can use any two + and any two -.

Re: Power Supply failure

My power supply has also died, but the only issue I can see is the fuse being blown. I replace the fuse and it immediately blows the new fuse as soon as I turn the power on. I can replace the power supply, but I fear it won't make a difference if something is drawing a lot of power still.

Re: Power Supply failure

Phillip, if you are running on a line voltage of 115 volts or so it is very likely that the problem is due to a power supply that is a touch marginal at that voltage. very few folks running on 220 volts are reporting many problems contact Prusa chat support and consider the popular Meanwell 350 watt upgrade... for your printer and save the replacement that Prusa sends you for another project like long strings of LED lights for the holidays

Re: Power Supply failure

My power supply failed this am after 3-4 months of printing.

Re: Power Supply failure

My power supply failed this am after 3-4 months of printing.

I ordered an LRS-350-24

Re: Power Supply failure

My power supply failed this am after 3-4 months of printing.

I ordered an LRS-350-24

and prusa is replacing the old one.

Re: Power Supply failure

Good Evening

Today while printing a small print my power supply started ticking.. Then about 15 minutes later POOF... It went up in smoke.. Anyone else had that happen?

How long do they warranty the PSU.??

Mine just died after only 4 months of use. They told me the parts were covered for one replacement under warranty for 1 year.

Re: Power Supply failure

Seems like the Prusa Power Supplies are consumable parts ....

Re: Power Supply failure

Seems like the Prusa Power Supplies are consumable parts ....

I would agree with thst based on my review.

Re: Power Supply failure

this seems to be linked to two things
the PowerSupply as specified is ok... But the manufacture of them can not maintain tight enough quality control to meet those specifications.
those run on 220 /240 volts seem to be more stable than those on 110/120 volts and those latter ones are more stable if their line voltage is in the 118 to 221 range volts. this is hard to nail down as only a few report on how stable their line voltage is. and so is mostly a guess.

My line voltage is very stable at 119.5 volts and my PS never clicks... I ran the line voltage down to 110 with a variac and the PS is clicking when it is in the 108 to 112 range and printing. so of course I run it at the 120.

All this indicates to me that the PS has an adequate capacity for its use if it is built with components that are all or even mostly on specificatfication but if in the normal run of production they slide below spec then the resultant PS will be prone to failure.

not knowing the terms of the Contract that Prusa has with its vendor for these we can only speculate further that the actual % of failed units is at a level that costs Prusa less than canciling that contract and then perhaps going to a more expensive Meanwell 350 watt PS would.

I would love to know how folks that have bought assembled printers and have line voltage in the under 112 volt range have faired? if they have a far lower return rate for failed PS that might indicate that PRUSA is testing under load and at 110 volts input the units and any that show signs of weakness (clicking ?) are sent to be used for kit production aimed at markets that have 220/240 mains... My kit was so intended as It came with a British fused plug for its power... and some error caused it to be sent to me in the USA.

Re: Power Supply failure

A little lower line voltage should never be a problem! "Normal" PSU's are usually rated 85...240V or 100...240V, so running on 110V should be normal. You just can't expect that all people will have ideal power line...
It's obvious that PSU's are poorly designed (that is, designed for EU market). I guess that warranty is the thing of manufacturer, not Prusa, so it's no expense on them. But still... bad reputation falls on Prusa, so i guess that they should really replace PSU with anything more stable - it doesn't have to be meanwell 350, but any other "better" same range PSU would do...

Re: Power Supply failure

You just can't expect that all people will have ideal power line...

True. In europe it doesn't hurt that much if the voltage drops to 220V or even 215 instead of 230V. You're still in the regular operation range of a switching power supply. But if you're going towards 100V, this is where you have max load on all components. We know already that the used passive cooled power supply operates at the maximum rating. The PWM heating is also not very power supply friendly. So there is no room for poor components in the power supply. Unlucky combination of this cases and your power supply is failing with a poooof.

That's why I'm using a UPS with automatic voltage regulation. It saved already couple prints due to short power outages and my MK2/MK3 are also happy for stable power source.

Re: Power Supply failure

Well, i guess that UPS is a must in any case. OK, printer has power failure function, but in the past it proved not working in some cases, so i rather don't rely on it. However, not all UPS devices has voltage correction, so a man has to watch out and pick the right one. In my region a good used UPS is not hard to get and in many cases it's cheap, too. Usually it just needs batteries replacing, but i have bigger ones anyway to extend work time.

Re: Power Supply failure

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

MK3 24v Power Supply PSU Troubleshooting

Common Questions:

Power Supply “clicking” during operation:
Totally normal behavior in Switch Mode Power Supplies - You’ll know it’s normal if the click sound correlates with the flashing of the LED on the heated bed: the bed draws a lot of current and the PSU audibly “clicks” as it delivers power. The bed LED will transition from solid to flashing as the bed reaches target temperature and the power is then delivered in short bursts to maintain the target temperature.

Supply “buzzing” during printing:
Older PSU’s had ferrite chokes on the smoothing capacitors that tend to “rattle” during axis motion - causing an audible buzz. Newer PSUs are the same construction but have the components physically snugged to the board to prevent vibration of the chokes.

About MK3 Fuses

The MK3 has four user replaceable fuses:

Figures on MK3 power consumption

Power Supply Unit (PSU) Ratings
The supplied “PRPZ-24-240” PSU is rated for 3.6A AC input and 10A on the 24V output according to the label.

AC Current Draw @ 120V
When running both heaters at the start of the print, our US MK3 draws maximum 215 watts @ 120V, that works out to <2A on the AC Supply, so the 5A AC supply fuse is more than sufficient.

MK52 Heated Bed
The MK52 bed measures ~3ohm resistance, calculating current draw at 24V we get ~8A, the supplied 15A fuse has plenty of headroom for normal operation.

40W E3D Heater
The 40W 24V E3D heater cartridge measures ~14.4ohm, calculating for amps that yields <2A, the supplied 5A fuse has plenty of headroom for normal operation.

Einsy, Fans & Sensors
The Einsy itself, Hotend, Part Cooling Fans, and Sensors consume ~120mA under testing with fans running 100%, negligible load to the 5A dedicated logic fuse. The motors are current limited at 940mA per motor, even if they were all running it would still be only 4.7A.

Power Consumption Summary
No “normal” printing situation will cause blown fuses.

On a freshly assembled printer this may indicate an assembly issue such as reversed wires or poor power connections, external power delivery problem such as surge or sag, or possibly a faulty power supply.

On a printer that has been printing and then fails, you should still check for obvious problems before replacing fuses or seeking RMA.

In either case - based on the specific failed fuse, you should investigate that aspect of the machine:

AC Fuse

Motor & Logic Fuse

Hotend Fuse

Heated Bed Fuse

About MK3 Power Panic
The “power panic” circuit is powered from AC supply directly and simply monitors for voltage drop on the DC supply ~23.2V and upon detection of a fault, commands a shutdown to the mainboard.

Panic Troubleshooting
We have observed poor connection between the power panic board and the PSU 24V positive rail - located in the base of the PSU assembly - cause “errant” panic triggering on an otherwise healthy PSU. This is an advanced troubleshooting step, you are not advised to disassemble the PSU assembly that includes the power panic circuit and the Fused AC Inlet.

Troubleshooting Summary

Noises
Buzzing from PSU may be normal if its caused by the vibration of the chokes on the capacitors or the plastic insulation sheet.
Clicking from PSU is probably normal if it clicks along with the flashing of the LED on the heated bed as the system heats.

Fuses
If one of the DC Einsy fuses fails, it’s unlikely a PSU issue, more likely it is a wiring problem you will need to investigate further using the details above.

If your AC fuse is blowing there is either an AC supply surge or a faulty PSU. A blown AC fuse is due to EITHER a surge on the 120V input or a load on the 24v rail IN EXCESS of 10A, such as a short circuit.

Final Note
Power Supplies fail, it happens. If a PSU failure occurs under warranty Prusa Research support will assist you with RMA.

Outside of warranty, replacements are available direct from Prusa Research and are not expensive. If a temporary workaround is needed while a suitable replacement is sourced, there are “off the shelf” options to keep you printing.

MK2S Specific: A reversed bed/hotend connection will blow your RAMBo hotend fuse, this is somewhat common on MK2S but highly unlikely on MK3 due to connector changes to make switching them by accident very difficult.

Note: The maths above are specific to the 24V system on the MK3, the MK2S uses specific 12V parts: fans, E3D Heater Cartridge, Motherboard, and obviously a different spec 12V PSU. The 24V system on the MK3 permits lower current draw due to higher voltage, and more silent operation of the motors at 24v.

We are not affiliated with Prusa Research in any capacity, I post this information in hopes it provides some clarity!

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"?