R.I.P. Power Supply

[Cameron]

My PSU died. It was a 30 amp Astron PSU that now blows a fuse from some internal short. I will go figure out how to fix it, but in the meantime, I bought this one from some of the forum recommendations. With the 12x12, it only gest a little bit warm from the whole load. Have only been using it for 2 weeks, but so far so good.
http://www.ebay.com/itm/Power-Supply...0AAOSw14xWLQEp

costs a bit more than some ATX PSUs, but it is not super huge so that is nice too.

[Mjolinor]

I really don't understand why they designed these things with heavy current low voltage heaters. You can get the cartridge heaters at pretty much any voltage, the Stratasys use 120 volt ones and I have a big selection ranging from 12 up to 400 volt. Same goes for the heated bed, mains operated silicon heat pads are available for a few pennies.

Switching AC is different from switching DC but it is no more complex and you only need a couple of amps of DC at the very most to power your micros and steppers. Altogether a lot cheaper and more reliable.

[spaceorange12]

If the fuse is OK then it should be an easy fix. Have you checked the temperature sensor for continuity, the one stuffed into the green inductor?

I got an ohm reading of 0.00, which indicates a short if I remember correctly.
What do I do?

[Mjolinor]

It should be 0, it is a safety thing that will go open circuit at some temperature, that will be written on it.

You do get them that work the other way round but I doubt this will be one.

If the fuse is intact then it really is unlikely to have failed and is most likely a broken connection somewhere.

Check the live an neutral inputs to the fuse. C4 next to the fuse is most likely across live and neutral so one leg shuld read 0 to the live pin and one leg 0 to the neutral pin. Is it a multi voltage input (110 - 230 or so) that you select somewhere or is it a multi voltage input, that will be specified on the sticker.

[spaceorange12]

Yep, both legs on C4 read 0 to their respective pins.
My power supply has a manual switch to select between 110/220v inputs, I have it on 110v which is correct for my area.

[Mjolinor]

I can't really offer a lot more but I do not think there is a lot wrong with it.

Check the 4 three legged devices that are fastened to the heat sink, two top right, two bottom middle. Are any of the three legs directly short circuit (0 ohms) both ways round. If they are then they are blown. What about the other thing plugged in just under the temperature sensor, is that to a switch or something or is it another sensor?

The resistor wedged between the two black capacitors at the top may have gone open circuit, check the value. Measure it with a meter and look at the colours on the resistor, work out what it shoudl be and see if it si correct.

[spaceorange12]

All of the heat sink components test correctly.
The plugin under the temp sensor leads to the case fan.
The resistor between the capacitors measures 0 ohms, supposed to be a 270 ohm resistor.

I am just as confused as you are, but I'm ready to just order another if there isn't an easy fix.

[spaceorange12]

I have come to realize that the fault does not lie in the power supply. I dug up another old power supply and tested it with the printer. This ps didn't turn on either. Any thoughts on what wiring problems might prevent a power supply from turning on? Note that the problem occurred while the printer was off so nothing changed between my last print and now.

[printbus]

Any thoughts on what wiring problems might prevent a power supply from turning on?

A short between 12v and ground will keep the power supply from turning on. When it detects the over-current, the power supply will protect itself by shutting down the output. Well, at least most of these switching power supplies will.

What electronics suite do you have (RAMPS vs RUMBA vs. ?)? Remove all the 12V connections to the electronics, and then reconnect them one at a time. In otherwords, connect power for the electronics iitself first. If that works, then connect motor power if that is separate for your electronics. Then try connecting heater power, etc.

[Roxy]

You might want to plug in the supply with nothing connected to it and see if it produces output voltage. Some switching power supplies need a load before they will turn on so this test may not do anything. But if you have voltage on the power supply with it not connected, you can start connecting one wire at a time and see when it loses power.