Fried PSU?

Hi everyone,

I modded my Velleman Vertex printer so that I could use it with a heated bed. I soldered my own Power expander and added a 12V 360W PSU that I had laying around. I installed everything and tested with a multimeter and everything was doing fine. The power expander worked and gave a nice 12V to the heated bed when the controller board wanted to. But I'd read here that you can speed up the heating process by turning the voltage adjustment knob on the PSU, so I turned it up to the maximum wich was around 13.xxV Everything worked fine and he did a great print with that setup. I wanted to connect a E3D fan directly to this PSU, but found out it was running very slow, so I checked the voltage the PSU was giving, wich was only 7.8V? I tried turning the adjustment knob but it keeps giving 7.8V and is making some flicky noises to now. The PSU is dead probably, but I want to know what caused it. Is it because it's only made for 12V, and I crancked it up to much? Very wierd, because it finished a print perfectly without the bed dropping temps. But now just after that it seems dead...

EDIT: It is a chinese PSU, just a Meanwell clone I guess

Thanks in advance,
Andreas

Edited 3 time(s). Last edit at 01/07/2017 09:45AM by Andreas15.

Buy cheap, buy twice.... If you want something that can perform above its limits, buy a proper one.

It worked perfect for 1 and a half year. So you want to say that the voltage regulation is just crap?

Switching power supplies are power limited. If you turn up the voltage, the maximum current they can supply goes down. DC power = voltage x current. Since power= current^2 x resistance, if you double the voltage (which doubles current) you quadruple the power.

When power supplies fail, they usually shut down completely. Since the voltage reads low you may have triggered some sort of protection circuit that will reset itself when you connect a load that is within the supply's limits. Try disconnecting everything from the supply and measure the output voltage. If it goes back to 13V, crank it back down to 12V and try using it again. If the voltage remains low, the supply will require repair (yeah, sure, you betcha) or replacement.

Operating anything at the limit of its specs is asking for trouble. If you are going to buy a new power supply, make sure it is capable of supplying the required power plus about 25-30% more. The price difference between a 320W and a 450W power supply is only a couple dollars and buying the higher power capable one will save you this sort of trouble and expense in the future. A few extra dollars spent up front is cheap insurance. Also, industrial type supplies generally have all sorts of protection built in that the only slightly cheaper "LED" power supplies don't have. If you see a bunch of certifications like UL/CE/TUV on the supply, it is probably a good one. Real Meanwell supplies have all those certifications. I recently bought a new in box 24V 8A Meanwell power supply via ebay for $40. A similar rated "LED" supply would have cost $30. The $10 difference is minor compared to the inconvenience of spending another $30 and waiting for a replacement power supply to arrive.

If your bed heater doesn't get hot enough, get one that's rated to deliver more power/heat. But if you do that, make sure that the MOSFET on the controller board can handle the extra power/current. If it isn't you may have to add an SSR with a heatsink and fan, or you'll end up replacing the MOSFET and maybe the controller board, too. This sort of crap is why buying a cheap printer with the idea of upgrading it in the future is a bad idea. When you change one thing it leads to a whole list of other things that have to change. You would have been better off spending more up front to get something that does what it is supposed to without any upgrades.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Switching power supplies are power limited. If you turn up the voltage, the maximum current they can supply goes down. DC power = voltage x current. Since power= current^2 x resistance, if you double the voltage (which doubles current) you quadruple the power.

When power supplies fail, they usually shut down completely. Since the voltage reads low you may have triggered some sort of protection circuit that will reset itself when you connect a load that is within the supply's limits. Try disconnecting everything from the supply and measure the output voltage. If it goes back to 13V, crank it back down to 12V and try using it again. If the voltage remains low, the supply will require repair (yeah, sure, you betcha) or replacement.

Operating anything at the limit of its specs is asking for trouble. If you are going to buy a new power supply, make sure it is capable of supplying the required power plus about 25-30% more. The price difference between a 320W and a 450W power supply is only a couple dollars and buying the higher power capable one will save you this sort of trouble and expense in the future. A few extra dollars spent up front is cheap insurance. Also, industrial type supplies generally have all sorts of protection built in that the only slightly cheaper "LED" power supplies don't have. If you see a bunch of certifications like UL/CE/TUV on the supply, it is probably a good one. Real Meanwell supplies have all those certifications. I recently bought a new in box 24V 8A Meanwell power supply via ebay for $40. A similar rated "LED" supply would have cost $30. The $10 difference is minor compared to the inconvenience of spending another $30 and waiting for a replacement power supply to arrive.

If your bed heater doesn't get hot enough, get one that's rated to deliver more power/heat. But if you do that, make sure that the MOSFET on the controller board can handle the extra power/current. If it isn't you may have to add an SSR with a heatsink and fan, or you'll end up replacing the MOSFET and maybe the controller board, too. This sort of crap is why buying a cheap printer with the idea of upgrading it in the future is a bad idea. When you change one thing it leads to a whole list of other things that have to change. You would have been better off spending more up front to get something that does what it is supposed to without any upgrades.

It was a 12V 360W power supply. The bed resistance was 1.3ohm, so I don't think I would be operating it at the limit of it specs, even when increacing the output voltage. If I measure it with 14V (about the output I increased the 12V to) it should make for a 150W, wich is a lot below the 360, right?

I've tried disconnecting everything but it stays on 7-8V. So I guess it's broken then...

I have multiple printers, you act like I'm a noobie that just bought his first printer and doesn't know shit. The vertex was my first printer and after having build multiple printers now I tought it would be cool to upgrade the vertex to. So I just added a power expander and that 12V PSU together with an MK3. That is adding things, not "a whole list of other things that have to change" right?

Al I want to know is if it is because these are cheap chinese PSU's, I've already ordered a new MeanWell by now, but I don't want to fry that one, so I want to be sure it is just the PSU and not something else in the system that is causing this...

Edited 1 time(s). Last edit at 01/07/2017 11:36AM by Andreas15.

Quote
Andreas15
Al I want to know is if it is because these are cheap chinese PSU's, I've already ordered a new MeanWell by now, but I don't want to fry that one, so I want to be sure it is just the PSU and not something else in the system that is causing this...

I don't think you did anything wrong, I think you were just unlucky with what was probably a cheap Chinese power supply.

I am guessing that the Velleman printer doesn't use Arduino/RAMPS electronics; but if it does and the printer has an LCD control panel, then I advise against turning up the voltage. In that configuration, the 5V regulator on the Arduino already gets too hot with 12V supply, and increasing the supply voltage makes it even hotter.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

No, indeed, I was running 2 seperate PSU's, because the Velleman board uses 15V. The other PSU was only running the heated bed.

To me it looks like something around the little potentiometer that adjusts the voltage is wrong. Because I can perfectly hook up a 12V fan to the PSU and it will run, but just slower. It's also no fixed value. I've measured from 7.4V to 8.7V... I'm just not sure, because it worked perfect for more than a year on 12V, just the setting how it came. And now after switching it to the Velleman and increasing the output a little it's dead a day later...

Is a MeanWell protected to shorts in the circuit it powers? Say the heated bed it is powering shorts, will the PSU be dead than, or do the MeanWells have a failsafe for that?

Quote
Andreas15
No, indeed, I was running 2 seperate PSU's, because the Velleman board uses 15V. The other PSU was only running the heated bed.

To me it looks like something around the little potentiometer that adjusts the voltage is wrong. Because I can perfectly hook up a 12V fan to the PSU and it will run, but just slower. It's also no fixed value. I've measured from 7.4V to 8.7V... I'm just not sure, because it worked perfect for more than a year on 12V, just the setting how it came. And now after switching it to the Velleman and increasing the output a little it's dead a day later...

Is a MeanWell protected to shorts in the circuit it powers? Say the heated bed it is powering shorts, will the PSU be dead than, or do the MeanWells have a failsafe for that?

Even the cheap Chinese PSUs are short-circuit protected.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I know, but is that only for shorts internally in the PSU or also for shorts in the circuit it is powering?

Quote
Andreas15
I know, but is that only for shorts internally in the PSU or also for shorts in the circuit it is powering?

It's for shorts externally.

What the cheap PSUs don't like is being run close to their maximum ratings for extended periods. But you should be OK with a MeanWell.

Edited 1 time(s). Last edit at 01/07/2017 02:59PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I know, but normally I wasn't to is maximum I think, with 360W for only a heated bed, wierd it failed than.

Well, I hope everything is just fine with the MeanWell

Believe me, there are worse failure modes for a switch-mode psu than a low output. I had a 12V power brick blow it's main input capacitor recently, which was enough to split the plastic case in two and blow one part across the room. What was left of the PSU was buzzing and getting very hot by the time I killed the power, but at least it didn't dump rectified mains voltage into the load. I don't look at plastic power bricks quite the same anymore...