Power supply cutting out.

Have just found my printer stalled, but this time with all fans stopped, even PSU fan.

Just thought I was beginning to iron out problems and tweak the printing, but now it's dead...

If I turn off the mains to the PSU and wait a minute it will come back on, but then cuts out again a few minutes later.

Good news is that it is not dead, bad news is you have a short some place. Best place to start is unplug everything, I mean everything, steppers, bed and all. Start with the supply board, switch on. If all is good, plug in the Duet board, if all is good, plug in the steppers and so on until you find the issue.

Dietee

Thanks, I'll try that when I get back home tonight.

Does anyone know at what current the PSU will cut out at?

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RS Ormerod #472

The label on my PSU says the 12V supply is rated at 32A. If you are exceeding that because of a short, I would expect you to find scorch marks.

It could just be that you have a bad PSU. Do you have another one you can try?

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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].

A PSU usually contains a short circuit protection:

Quote

Short Circuit Protection (SCP)

This protection constantly monitors the output rails and if it finds an impedance of less than 0.1O then it immediately shuts down the power supply. In other words if somehow the output rails are short-circuited then this protection kicks in and shuts down the PSU, to prevent damage/fire. ATX 2.31 spec states that the two +12V rails should have separate short circuit.

Source: [www.techpowerup.com]

I had a look, but did not see any sign of scorch marks or smell of burning. That was my first thing I looked for when it stopped the second time.

I'll ask the IT department if there are any spare PCs knocking around that I can borrow a PSU from.

I see on the wiring loom from the PSU to power board there is a large multiway connector and a 4 pin connector with 2 black and 2 yellow wires. Which wires carry the current to the machine? I assumed it would be the 4 pin one, as this measures at 12v, but does the 24 pin one carry any current? I'd like to try and measure the current with a clamp meter.

Right, been to the IT department and raided the "scrap PC corner", I've got a standard ATX PSU to try tonight, lots more there to scavenge bits out of.

I also found a HP server PSU which will give upto 80A at 12V! I've found the info to get it running on it's own and have soldered the links in place. Obviously I won't try this one until I've proven there's no short circuits. Might also be an idea to add a fuse inline.

I have tried the 2nd hand ATX PSU, and after the usual dozen or so attempts to connect with the web interface, all is looking good. I'm now halfway through a 3 hour print and keeping my fingers crossed it will be OK.
It was interesting to note the wires going to the 4 pole connector on the alpine PSU were only 20AWG approx 0.5mm^2. The wires on the HP ATX unit are much thicker 20AWG ~ 1.3mm^2.
Also the fan seem to slow down less on heater bed switch on.
I think I'll just send the Alpine unit to the scrap pile.

Glad you got it working. I too have an Alpine PSU, and it seems to be working OK, although the fan slow-down is very noticeable when the bed heater turns on. I guess you got a bad unit, and suggest you ask RRP for another one.

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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].

Thanks Dave, but I don't think I'll bother asking for a new one, I think the 2nd hand ones I can get from work are better quality. They certainly seem more substantial, with decent sized capacitors inside.

He already has! Do you still want one, tim_h? I'm still a bit concerned that you have may have a short somewhere. Can you test the resistance of the heated bed with a multimeter? With the power off, put the proves on the two big contacts, where the ribbon cable connects. It should be around 1.3 ohms. If it's a lot lower, like below 1 ohm, it will draw a lot more current.

Ian
RepRapPro tech support

Hi Ian, the printer has now been running for over 2 hours without the PSU cutting out. I can't check the resistance at present as it is still running, but I'm pretty sure there is no short circuit. Maximum current draw is under 7 amps with bed heater on at present.
I think for now we can assume the Alpine PSU was a faulty.
You can cancel my request for a replacement, thanks.

Edit: Sorry, just re-checked the current readings. Bed current is 10 - 10.5A depending on temperature, total load is in the region of 14- 15A.

Edited 1 time(s). Last edit at 01/02/2014 06:18PM by tim_h.

A couple of points raised on this thread. The 24 pin and the 4 pin ATX connectors have 12v circuits. The ATX spec may allow for these to be different supplies but the ACE version does indeed only have one (likewise Alpine I assume).

Rory