Power Supply failure  

Re: Power Supply failure

Swapped mine out with the NES-24-350, clicking and rattling are gone and i've been printing on it for a while now. It's been great.

For those about to do it themselves:
1. This printed parts set works great: https://www.thingiverse.com/thing:2812350

2. You will need longer M4 screws for where the PSI mounts to the Z&X frame, so get flat ones and not the tapered ones. I think 12MM will work. If you only have tapered my M4 12MM ones work but they're not the right kind. You will need flat washers between this same vertical piece and the frame, or at least I did because my machine screws stuck a bit out from the printed part.

3. You will need M4 screws if you want to attach the PSU to the printed part all the way around. On the side you can use longer M4 12mm tapered screws but on the back where the insulation is you will need shorter screws so that you're not pressing on the insulation.

4. Stock wires are too short by a couple inches. It doesn't look like when you're putting it together, but trust me they are. As others have said if you are going to extend the wires solder or properly crimp don't just twist.

5. Stock wire gauge is 16GA

6. The thingiverse link above fits the power panic board.

7. Take a picture of the PSU before you excitedly start taking things apart 😉

8. Some people don't like the fan noise from the PSU. I thought it was going to be an issue and it's totally not. The fan is really quiet and only turns on every now and then for a few seconds. It's really not a big deal IMO.

9. Maybe its bias but I feel like everything heats up faster. Doubt it though.

10. I used a volt meter along the way to test leads and make sure I was getting 24V, then flipping the leads to make sure i got -24V. This was good because it allowed me to confirm along the way that I didn't get anything crossed up. If you don't have a volt meter use this as an excuse to get one 😉

What a great write up! I think I may go ahead and get the LRS version and do this mod. If Prusa is having issues with the QC of their power sources then why no get something proven to hold up even if it's a couple bucks more. I found the LRS on amazon for $36. Thanks for posting this! I had posted in another thread before I found this thread that my printed died and I'm pretty sure it's the power source.

Re: Power Supply failure

QUESTION to the electrical experts. I was unpacking my MK3 today and just eyeballed the contents in each box when I came across the power cord "110/120v".
Thinking of all the computer and electrical devices I've built, repaired or replaced the power cable seemed very light and flimsy compared to all that I've used.

COULD the damage to power supplies be affected by an under rated power cord? I'm not pointing to the power cord, just wondering....

Re: Power Supply failure

Swapped mine out with the NES-24-350, clicking and rattling are gone and i've been printing on it for a while now. It's been great.

For those about to do it themselves:
1. This printed parts set works great: https://www.thingiverse.com/thing:2812350

2. You will need longer M4 screws for where the PSI mounts to the Z&X frame, so get flat ones and not the tapered ones. I think 12MM will work. If you only have tapered my M4 12MM ones work but they're not the right kind. You will need flat washers between this same vertical piece and the frame, or at least I did because my machine screws stuck a bit out from the printed part.

3. You will need M4 screws if you want to attach the PSU to the printed part all the way around. On the side you can use longer M4 12mm tapered screws but on the back where the insulation is you will need shorter screws so that you're not pressing on the insulation.

4. Stock wires are too short by a couple inches. It doesn't look like when you're putting it together, but trust me they are. As others have said if you are going to extend the wires solder or properly crimp don't just twist.

5. Stock wire gauge is 16GA

6. The thingiverse link above fits the power panic board.

7. Take a picture of the PSU before you excitedly start taking things apart 😉

8. Some people don't like the fan noise from the PSU. I thought it was going to be an issue and it's totally not. The fan is really quiet and only turns on every now and then for a few seconds. It's really not a big deal IMO.

9. Maybe its bias but I feel like everything heats up faster. Doubt it though.

10. I used a volt meter along the way to test leads and make sure I was getting 24V, then flipping the leads to make sure i got -24V. This was good because it allowed me to confirm along the way that I didn't get anything crossed up. If you don't have a volt meter use this as an excuse to get one 😉

What a great write up! I think I may go ahead and get the LRS version and do this mod. If Prusa is having issues with the QC of their power sources then why no get something proven to hold up even if it's a couple bucks more. I found the LRS on amazon for $36. Thanks for posting this! I had posted in another thread before I found this thread that my printed died and I'm pretty sure it's the power source.

For those of you that replaced your PSU did you keep the same fuse in the switch as factory? I think it's a 5A fuse.

I just put in an LRS 350-24 tonight. I printed the mount from thingiverse and everything went together good except for a misalignment of the bottom plate nut on the right side. I had to dremel out the plate to get that nut to line up. Wire lengths worked out fine and I reused the on/off switch and 110v receptacle. I left the fuse installed that was there and everything is running fine. As posted above the fan is a little loud, but only comes on every once in awhile. I ordered another fan tonight to see if it is quieter.

Re: Power Supply failure

QUESTION to the electrical experts. I was unpacking my MK3 today and just eyeballed the contents in each box when I came across the power cord "110/120v".
Thinking of all the computer and electrical devices I've built, repaired or replaced the power cable seemed very light and flimsy compared to all that I've used.

COULD the damage to power supplies be affected by an under rated power cord? I'm not pointing to the power cord, just wondering....

No issue. This printer doesn't pull that much power at all, only ~200W, call it 3-4A at 120V with generous amounts of PSU inefficiency. Your outlets are likely rated at 15A for driving higher power stuff, which might need a heavier gauge cord. For a short cord with 3A AC, the original cord is fine.

Re: Power Supply failure

QUESTION to the electrical experts. I was unpacking my MK3 today and just eyeballed the contents in each box when I came across the power cord "110/120v".
Thinking of all the computer and electrical devices I've built, repaired or replaced the power cable seemed very light and flimsy compared to all that I've used.

COULD the damage to power supplies be affected by an under rated power cord? I'm not pointing to the power cord, just wondering....

No issue. This printer doesn't pull that much power at all, only ~200W, call it 3-4A at 120V with generous amounts of PSU inefficiency. Your outlets are likely rated at 15A for driving higher power stuff, which might need a heavier gauge cord. For a short cord with 3A AC, the original cord is fine.

This is likely correct, easy enough to test anyways, just measure voltage drop on the power cord, if its under 3% you are fine, if its over then maybe upgrading the cable is a good idea.

Re: Power Supply failure

Thanks for posting pictures, this really concerns me. I lost a house, animals, and everything I own to an electrical fire. These wide spread PSU issues have been really concerning. I think at this point I'll cancel my order and buy the MK2S.

They have gone on record and said PSU is from same manufacturer as mk2 PSU so i doubt the Mk2 PSU is of any higher quality.

Re: Power Supply failure

Thank you Paul and Nathan,
I didn't think it was anything, but I like to approach a problem from 20 different ways. I haven't even put together my printer yet, just unboxed and did a quick survey because of minor crushing on a corner during shipping.
The packing was great though and everything inside looked solid.

Re: Power Supply failure

QUESTION to the electrical experts. I was unpacking my MK3 today and just eyeballed the contents in each box when I came across the power cord "110/120v".
Thinking of all the computer and electrical devices I've built, repaired or replaced the power cable seemed very light and flimsy compared to all that I've used.

COULD the damage to power supplies be affected by an under rated power cord? I'm not pointing to the power cord, just wondering....

No issue. This printer doesn't pull that much power at all, only ~200W, call it 3-4A at 120V with generous amounts of PSU inefficiency. Your outlets are likely rated at 15A for driving higher power stuff, which might need a heavier gauge cord. For a short cord with 3A AC, the original cord is fine.

Agreed. I've done a fair amount of monitoring of power consumption both on the AC side and DC side of the printer. When consumption is totally maxed out (during preheat), the printer is pulling ~240 DC watts from the PRUSA PSU, and the PSU is pulling ~290 AC watts from the wall. 290watts @ 120v AC = 2.4amps AC.

2.5A should be no problem even for a lightweight power cord. Even the cheaper/thinner ones (18awg) are typically rated at 10amps, though I typically swap then out with much thicker ones if they're being used for anything over 4 or 5 amps.

Re: Power Supply failure

Is the existing wire cabling completely transferable to the MeanWell? In that, no wire extension required, and cable can be placed in same cable management order as the original installation? Seems to be some disagreement on that here.
I have had no problems with the stock PSU, but want to have one ready to go if I have to. Have already printed the enclosure. Thanks for any information. 😀

Re: Power Supply failure

Is the existing wire cabling completely transferable to the MeanWell? In that, no wire extension required, and cable can be placed in same cable management order as the original installation? Seems to be some disagreement on that here.

There is no disagreement. If you swap to the MeanWell the stock cables won't be long enough. Buy some cable and make a new one that's the appropriate length.

Re: Power Supply failure

Is the existing wire cabling completely transferable to the MeanWell? In that, no wire extension required, and cable can be placed in same cable management order as the original installation? Seems to be some disagreement on that here.
I have had no problems with the stock PSU, but want to have one ready to go if I have to. Have already printed the enclosure. Thanks for any information. 😀

I installed the Meanwell LRS 350-24 and didn’t have to change any of the cables. The stock fan in the LRS was loud and I replaced it with this one: https://www.amazon.com/gp/product/B00N1Y4ARG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

The wires on the replacement fan are backwards so you have to fix that, but it is nearly silent.

Re: Power Supply failure

Mine failed last Saturday. I would say that the printer has a couple of weeks of print time. I was 5 hours into a 7 hour print when the failure occurred. I was printing PLA @ 215/60. All nine of my printers are powered through several UPS so I know the power was clean.

When I checked the print job the printer had stopped, the UPS alarm was on (the other UPSs were fine, none showed a power failure. I think the alarm was caused by an over current condition). The fuse on the PS had blown. I replaced it and when I turned the printer on the magic smoke was released.

I have reported the problem and am waiting to see what Prusa will do. In the mean time, I have ordered two 350W supplies for both of my MK3 printers.

Re: Power Supply failure

Question, could this be related? There seems to be a grounding problem on the main board. It talks about being a 110v problem and not so much a 220.

Random resets - earthing problem - easy fix
https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/random-resets-earthing-problem-easy-fix--t14986.html

MK3 resets while printing
https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/mk3-resets-while-printing-t14657-s10.html

Re: Power Supply failure

While my printer has been almost flawless, the power supply clicking is driving me crazy so I might mod it out anyways...

Re: Power Supply failure

Question, could this be related? There seems to be a grounding problem on the main board. It talks about being a 110v problem and not so much a 220.

Grounding is pretty complicated thing. The PSU has an earth ground. The PSU is attached to the frame. So the frame is earth grounded, too (If your house installation is correct). The mentioned "fixes" are putting the earth ground to a digital "-" ground. It can be pretty dangerous.

I assume in their cases, the earth ground is bad or just missing in their installation. In some circumstances the digital ground fluctuates and that's leading to a reset. Attaching digital ground to earth ground helps in that case because it stabilize the PSU and digital output.
But if your installation is correct, you might guide electrostatic discharges through the ENSEY board. And you definitely don't want to do this.

Re: Power Supply failure

Question, could this be related? There seems to be a grounding problem on the main board. It talks about being a 110v problem and not so much a 220.

Grounding is pretty complicated thing. The PSU has an earth ground. The PSU is attached to the frame. So the frame is earth grounded, too (If your house installation is correct). The mentioned "fixes" are putting the earth ground to a digital "-" ground. It can be pretty dangerous.

I assume in their cases, the earth ground is bad or just missing in their installation. In some circumstances the digital ground fluctuates and that's leading to a reset. Attaching digital ground to earth ground helps in that case because it stabilize the PSU and digital output.
But if your installation is correct, you might guide electrostatic discharges through the ENSEY board. And you definitely don't want to do this.

nikolai, I appreciate the explaination. I wouldn't have made the changes indicated unless I got a go ahead from PRUSA. I learned alot about ground and ground between buildings with networking. I was just wondering since this issue was just on the 110v circuits and not the 220 like the power supply problem if they could be related.

Re: Power Supply failure

Add me to the long list of power supply failures.... it just happen whilst I was watching the last 5 mins of a 10h print. Little puff of smoke. 110v.

I guess I'm going to spend the morning with support... SIgh!

Re: Power Supply failure

Add me to the long list of power supply failures.... it just happen whilst I was watching the last 5 mins of a 10h print. Little puff of smoke. 110v.

I guess I'm going to spend the morning with support... SIgh!

Did some more digging and think I found the fault. Resister R4 has blown. It's difficult to see in my picture taken through the vents, but it's exactly the same problem found by jltx in this post: https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/power-supply-failure-t13443-s90.html#p61363 . The resister has a crack through it and a brown smoke stain on the rear side. Like other experiences my fuse near the power connector did blow, but of course, replacing it didn't make a difference.

I'm going to forward this on to Prusa support, but unless they have found a substitute power supply, I'm not sure I'm going to be able to trust it.

Re: Power Supply failure

I'm going to forward this on to Prusa support, but unless they have found a substitute power supply, I'm not sure I'm going to be able to trust it.

That's where I'm at. I had one fail, and the second they sent would drop to zero volts randomly when heating. I've got my 3rd prusa supply, but I'm using a meanwell. I assume that the prusa supply will blow eventually and I don't want it to take my Einsy or my house with it. Since I have the meanwell (to bridge the replacement gap, 2 day delivery vs a week for me from Prusa), I might as well use it as the more reliable supply.

Re: Power Supply failure

Did some more digging and think I found the fault. Resister R4 has blown...

As already mentioned this is not the root cause. It's just a correct point of failure once too much current is flowing through the circuit.
Why there is too much current flowing, is a big mystery where PR need to figure out soon.