power supply overload

I am ready to try my first print but I can't get my extruder heater to turn on.
My heatbed heats great. All my motors work great. but as soon as i set either of the two choices for my extruder heater temperature, the power supply kicks off and shuts my printer down. I have a switch on the power supply and it just clicks until i turn the heater to off, then everything will power back up fine.

My printer was supplyed with an AT 300w but none of the plugs matched the fans so i switch it out for a 430w ATX that i had laying around.

Any suggestions.

The total wattage of the PSU is not what's important. Yes it's an indication of how beefy the PSU is, but you need to pay attention to the wattage on the specific rails you are using. If you have RAMPS, then you will be using 2 12 volt connections. What is the power rating on the 12volt rail? Are there two of them, or are they connected together internally. You will need to supply a minimum of 11 amps and ~5 amps on the two RAMPS rails, but it's safest to supply a bit higher that that. If youe PSU has 2 12v rails, then it's best to use separate rails from the PSU for each RAMPS rail.

My PSU that I got from ebay provides 30 amps total at 12v, and I've never had an issue with it shutting down

I got into this because its cool, and i have been making G-code for over 30 years (CNC Programmer). That lingo i understand, however, im extremely green on the printer side.

Terms im not familiar with RAMPS, Rails, PSU.

I'll take a stab at these:

PSU = power supply unit
Rails = linear guides????
Ramps= something to do with amps??

Please clarify.....Sorry for being such a noob, but we all have to start at the beginning



added later: just found out ramps is a motherboard..... i use a Sanguinololu.

Edited 2 time(s). Last edit at 09/26/2013 01:14PM by makovai.

RAMPS is the printer control board - Reprap Arduino Mega Pololu Shield - that sits atop the arduino. I'm not sure if that's the electronics you're using.

The term rails in this context is basically an electrical circuit. You ramps has 2 distinct circuits - it's why there are two power connections and 2 differently rated fuses on the RAMPS. One rail operates the heated bed and has an 11A fuse. The other rail does basically everything else and has a 5A fuse.

Your power supply should have a sticker on it - or maybe it came with a spec sheet - that tells how many amps it supports at each voltage level. Many power supplies also have multiple rails. These rails are electrically isolated from one another - and may have different specifications. For example, you might have 1 12V rail that's rated for 5 amps, and another for 7 amps. These numbers are just for example, but you need either two 12v rails, one that supports 11 Amps and the other 5 Amps, or 1 rail with 2 connectors that will support 16 (or more) amps

So, did you buy a fully assembled printer? I'm guessing this because you said your printer came with a 300 W PSU. What kind of printer is it?

My printer uses RAMPS controller board, and as jbernardis has said, RAMPS takes two 12V power input. My PSU has two rails, but there was no indication which rail has how much wattage, so I just assumed the load is evenly distributed into each.

Yes, based on the symptoms you stated, I would guess is a case of PSU overload. The component that consumes the most power is heated bed. I had a view instances of PSU failing (tripping and stopping) in the middle of print, and it only happened when I was printing with ABS (= higher bed temperature).

Since the last PSU failure, I've put some make-shift insulation (cardboard covered with aluminum foil on top) under the heated plate, and seems like the heated bed reaches to the operating temperature slightly faster. I hope this is also an indication it would consume less power now, and consequently stop overloading the PSU.

I've started asking people around if they have any old/unused PSU or desktop PC. I would like to have a separate PSU for heated bed. I read it somewhere setting up a dedicated PSU for heated bed with RAMPS is quite simple, but I can't remember where I saw it.

Using a separate power supply for the bed is easy - at least with RAMPS. Just connect it to the 11A connector on the RAMPS and you are done.

Did you check the heater resistor or its lead wires dont have a short?

Thermally insolating the heater bed is a good idea just to save some power, but presumably the power supply is chosen to match the high end of power use from it.

> I got into this because its cool, and i have been making G-code for over 30 years (CNC Programmer). That lingo i understand, however, im extremely green on the printer side.

Cant imagine they still need much g-code done manually for CNC? Not for 3d printing, at least.

bernardis Wrote:
-------------------------------------------------------
> Using a separate power supply for the bed is easy
> - at least with RAMPS. Just connect it to the 11A
> connector on the RAMPS and you are done.

I would assume that "11A connector" is one of two 12V connectors on RAMPS? Is there a label on the board indicating which one is this 11A connector and which one is the other one? Sorry, I don't have access to my printer right now and even if I did, I am known for not being able to see those little labels printed on the circuit board. LOL

Does the extruder heat work with everything else turned off? The printbed uses signifigantly more power than the extruder, so if the printbed works by itself but the extruder doesn't, then there's a short.

Look at this diagram. It shows which power connector is the 11A one (notice the 11A and 5A written on the board itself)

Wow! so much information. Thanks guys.
To answer a few questions:
I built this myself but I asked them to throw in a PSU. It is a I3X with a Sanguinololu MB
The heated bed heats just fine. But the extruder heater doesn't heat no matter what I do.









> Cant imagine they still need much g-code done
> manually for CNC? Not for 3d printing, at least.
LOL... nope, I Stair at Mastercam all day now.

your power supply if it's working properly has plenty of capacity. Are you connecting BOTH RAMPS connectors? The 11A one is just for the Heat Bed. The 5A is for everything else.

Would it be possible to connect the hot end directly to the power source. You can probably even rig it so the thermistor is still in play and the RAMPS thinks it is heating the board. That way you can monitor the temp. Or if you have an IR thermometer or other way of measuring the temp, you can just simply connect to the PSU. It's a simple way to rule out the hot end.