michael.w15
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Power Supply failure

Jan 08, 2018 1:19 am

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.??

michael.w15
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Re: Power Supply failure

Jan 08, 2018 4:24 am

So I dug a bit deeper... The issue with the clicking and the PSU is a bad thermistor NTC 5D-11. It failed rather violently with flames and everything. Thermistors are known to making clicking noises when they are not functioning properly. Leading to a failure and usually a blown fuse, which I have as well.. I've opened a ticket with Prusa.
Last edited by michael.w15 on Jan 08, 2018 2:21 pm, edited 1 time in total.

scott.w12
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Re: Power Supply failure

Jan 08, 2018 7:40 am

Interesting...A clicking PSU just before the bed reaches temp seems to be a common issue. Mine ticks right before the bed reaches temp, but not during prints.

nuno.m2
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Re: Power Supply failure

Jan 08, 2018 9:50 am

NTC is not a supplier.
NTC stands for Negative Temperature Coefficient.

It's a thermistor issue.
Maybe this is the issue that is holding up shipment in the past week, as told by a support representative? Or a new one? Who knows...

dryja123
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Re: Power Supply failure

Jan 08, 2018 3:33 pm

Would you mind posting a few pictures of the failure?

yves.t
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Re: Power Supply failure

Jan 08, 2018 3:55 pm

I contacted support about the clicking of the power supply on my MK3 while the heat bed is heating.

"The clicking noise is not a concern at all. It does not harm the PSU at any way and will be taken care of in future FW updates."

I wonder how they will fix the PSU thru a firmware update. And now I'm a little worried after hearing about a PSU failure.

I guess it's something to be aware of.

nuno.m2
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Re: Power Supply failure

Jan 08, 2018 4:08 pm

They will adjust the heatbed PWM frequency and resolution in firmware to stop that clicking.

michael.w15
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Re: Power Supply failure

Jan 08, 2018 4:15 pm

Here are pics from the failed power supply. When it failed there was a flash of fire from inside the case. The printer had been printing for almost 70 hours when this happened.

The first pic is the blown thermistor. there may be other parts that let out the magic smoke as well.

IMG_2667.JPG
Blown thermistor
IMG_2667.JPG (335.15 KiB) Viewed 13232 times

The second pic is the chunk of thermistor that fell out of the PSU case.

IMG_2674.JPG
Chunk of thermistor that came out of case.
IMG_2674.JPG (306.4 KiB) Viewed 13232 times

dryja123
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Re: Power Supply failure

Jan 08, 2018 5:36 pm

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.

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Protoncek
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Re: Power Supply failure

Jan 08, 2018 6:05 pm

Cancel order? Well...in MK2S power supply is very similar, only that it's 12V. So noone can guarantee you that it won't "explode". These PUS?s are all pretty much similar built, so it can happen or it can't happen, regardless of model...
Don't cancel just because of this issue. I understand your fear, but in your place i would rather put some fire/smoke detectors in room where printer is located.

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