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I think I got a bad PSU  

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Vexzilla
(@vexzilla)
New Member
I think I got a bad PSU

Just finished assembling my MK3S, and it's not turning on.

Outlet works with other things plugged in, I tested the outlet and it is wired correctly. Proximity tester shows the cord between wall and unit hot, but everything else is cold.

PSU light doesn't turn on, no screen activity.

At this point I'm thinking the PSU may be bad, but I'm not sure how to check more authoritatively.

Any other things I could check while I wait for support to get back to me?

This topic was modified 5 years ago by Vexzilla
Posted : 09/05/2019 6:05 am
cwbullet
(@cwbullet)
Member
RE: I think I got a bad PSU

Don't check with your tongue, us a micrometer to check for DC current output across positive and negative.  It could also be a bad fuse.  

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Chuck H
3D Printer Review Blog

Posted : 09/05/2019 9:52 am
Vojtěch
(@vojtech)
Honorable Member
RE: I think I got a bad PSU
Posted by: charles.h13

Don't check with your tongue, us a micrometer to check for DC current output across positive and negative.  It could also be a bad fuse.  

Well, i'd rather use a multimeter to measure the DC voltage. Otherwise it could quickly get quite sparkly. 😉

Posted : 09/05/2019 11:42 am
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(@)
Illustrious Member
RE: I think I got a bad PSU

The power supply is a pretty simply device: only a few wires to connect, but any one of those wires in the wrong place will result in a shutdown.

Many folk think it's a race to build the printer as fast as possible and end up wasting days and weeks because of some small mistake. Triple check each of the wires to the EINSY power strip is connected properly.  The stripe on the wire is important.  Reread the manual to make sure the striped wire goes to the correct strip connector. 

If it is wired correctly, the best next test is with a voltmeter, to see if 24v is present at the power strip. 

Posted : 11/05/2019 10:27 am
Milos V.
(@milos-v)
Prominent Member
RE: I think I got a bad PSU

My original MK2 power supply is switchable between 230 and 110 V. Maybe it could be wrong position of this switch. Not sure about the behaviour running PS set for 230V on 110V but it might be worthy to check the position (not change, just check 😉 )

Milos

Posted : 11/05/2019 12:58 pm
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(@)
Illustrious Member
RE: I think I got a bad PSU

Prusa MK3S manual lists: Power supply: 90-135 VAC, 3.6 A / 180-264 VAC, 1.8 A (50-60 Hz)  -- a switch makes sense.

That said, unless the strap is inside the fuse, or switch is against the frame, I'm not seeing it on my MK3. 

 

The PS manufacturer says this, and photo below (click to enlarge) shows a switch:

Input voltage 90-132V / 180-264V AC according to switch setting

 

Posted : 11/05/2019 5:54 pm
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