Heatbed shutting off power supply.

Ive been printing some with my printer and the part are looking good. So I started printing the ImMoov finger starter. Shut down for the night and when I was going to print the next day the heatbed wouldnt come on. Left it untill today and the wiring looked good, and rechecked every setting I could think of and everything looked to be ok. so redid the wiring and put on a new ramps board, got everything hooked up and the heatbed got hot everything checked out releveled ready to print. Went to turn on the heatbed to warm up and it would shut off the power supply. Rechecked everything looks ok, tryed again and same thing. Decided to see if I could print a small part in ABS without the heatbed
started the hotend and loaded the Gcode and hit print and the power supply shut off. All the motors work, endstops ect, but when I turn on the heat bed or try to print the PS shuts down. When the PS shuts down from the heatbed nothing works no motors or anything until I shut off the heatbed then after a few seconds the PS will come back on and the motors and everything works. But when I leave off the heatbed and just run the hotend and then try to print after the PS shut off the only way to get things to work is to shut down pronterface and then reconnect and then the motors will work again and all. So Im thinking maybe the power supply went bad for some reason or there is something Im missing. I allso hooked the heatbed to the Xbox ps I have and it got hot but I have not temp control, and then there still the proble of the shutdown when I try to print. Tryed to hookup the Xbox ps to ramps and couldnt get it to work right, underpowered or something. Still looking things over.

I have a Getech 12v 29A single switching power supply.
MK2B heatbed
Mega 2560 R3
Ramps 1.4

Everything was working and was printing good parts and then this, spend more time working on this printer than I do printing.

Thanks.

Are you sure the hot-end resistor is not shorting to ground somewhere?

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Waitaki 3D Printer

Ok replaced the hot end rechecked all wiring, after taking eveything apart and looking for anything that could be a problem. could find nothing wrong. Hooked the heatbed up to the Xbox ps and works. Got everything back together and all looking good. Turned on the heatbed to heatup and it came up to temp then swiched off temp started falling.
Cannot get to switch on to warm up, the temp read right for room temp. Out of ideals at the moment. Dont know about swiching off settings in software then trying to print ABS without a heatbed. Was using heatbed printing on glass, with blue tape and a shot of hairspray. Parts stuck tight. Was getting nice looking part printed.
Hope someone has some ideals, I got nothing at the moment.

Thanks.

So the heat-bed is not shutting the PS down now?
Have you got a fan blowing continuously on to the Ramps board to cool the yellow fuses and the heat-bed Mosfet. A fan ( and a heat sink on the 'Fet) is absolutely essential

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Waitaki 3D Printer

No not after a disabled the temp settings for the bed in sli3r and made a new gcode for the part I was trying to print without the heatbed on. Before the heatbed quit working, when I would turn on the heatbed or hotend on in pronterface the ps fan would speed up. But after it quit working when I try to run the heatbed it would shut down the ps and I would have to turn off the heatbed then dissconnect pronterface and then restart to get anything to work. Ive tryed two differnt ramps boards and same thing. The thermalresistor
seems to read the room temp right, so I dont thinks thats it? But I ordered new parts anyway. The heatbed will heat up when connected to a seprate ps and not connected to ramps, but I have no temp control that way. So right now I dont know what to do other than order parts. And I will try to get a fan closer to the fuses.

Ok moved the fan so it blows right on the fuses ect and the room temp was about 65 ferenhet. No go. Ive slowed down my print speeds earlyer so I dont think anything should be working that hard. Cant belive that two ramps boards could go bad at such low temp. If so maybe I should try some other board if ramps has such a flaw. So what next cant think of anything else to try other than order new parts.

As for the power supply. When I turn on the hotend the ps fan will speed up as it draws more power.
But when I turn on the heatbed it dosent speed up as if the heatbed isent drawing more power. But will stop the motors ect from working until I dissconet pronterface and then restart it. So I dont think its the ps, the thermalresistor reads room temp right so I dont think that the problem. The heatbed will warm up when connected to a ps directly ot I think its ok. I havent changed any settings in software. So must be the ramps board, but two of them going bad when nothing should of gotten that hot. Love this thing when it works but it has been a real pain to get running and keep running. But I will get this to work.

Been doing some reading. And to fix this I should desoder both of the yellow PTC fuses and replace them with wire that will fit. Then on the 12V power input wires from the power supply to the ramps install the white plastic fuse holders with 15 amp automotive fuses? Seems that there is a problem with the ramps not being able to handle the current in high demand. Looks to be a easy fix if this is correct. Or is it a 5amp fuse for one fuse and 15amp for the other? A lot of this is clear as mud. But kind of fun in a sick way.


Ok 5amp fuse on the 5A line and the 15amp fuse on the 11A line because 11amp auto fuses are hard to find.

Edited 2 time(s). Last edit at 04/01/2014 09:43PM by romon.

It could also be possible the mosfet was damaged at some point too?

Measure the voltage of the heated bed pins (keep one lead on one of the GND screws where the power is connected, and check the + and - pins with the other lead on the D8 pins) both the + and - should read approx 12V when the bed is turned off.

Measure the resistance of the heated bed? Should be above 1ohm

If you don't have a multimeter, maybe try unplugging the heated bed and turning on the bed in the software and see if it still trips? then connect say a 12V fan to the heated bed port and switch on an see if it works?

I have a similar setup (mk2b and ramps 1.4) and don't have a problem with it on my prusa i3.

I think you need to solve the heatbed problem rather than muck about with the yellow fuses.
Let's back up a bit...
Does the power supply shut down if you switch on the hot-end only?

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Waitaki 3D Printer

No hotend works just fine. Went ahead and did the hack on one of my ramps boards and still have the same problem. Its not so much that the heatbed is so much shutting down the ps but that it dosnt power it up like when I turn on the hotend. When I trun on the hotend the fan on the ps speeds up as it puts out more power the supply the hotend an it starts to get hot. When I trun on the heatbed the fan on the ps dosent speed up and it dosent heatup. The thermistor seems to be working right as it reads room temp corectly and the heatbed will get hot if I connect it to a Xbox ps. Everything else works just fine. One day the heatbed was working just fine and Im getting good prints, the next day trun on the printer and the heatbed dosent work. The hotest its been in the room where the printer is was 65 degrees and a fan blowing twards the ramps. And I have two ramps boards and both of them have the same problem. So any ideals would be great.

Thanks for the help.

What voltage do you measure between + and - on D8 when you switch the heat bed on? And what voltage do get on D8 when you switch the heatbed on with the wires to the heatbed disconnected at D8?

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Waitaki 3D Printer

Ok found the problem, me. I took off that ramps board that I did the hack on and was going to put on the other one, to get good voltage readings, and after I got everything hooked back up the heatbed started working? Two things I hate is when something dosent work right and I dont know why, and when things start working and I dont know why? Got to thinking about it, and when I did the hack on the ramps I installed the inline fuses on the wires from the power supply, so when I install the unhacked board I cut them off. ???? Got to think about it and when I first put things together I put some sodder on the ends of the wire from the ps, so the wires wouldnt fray and would be easyer to get them into the termanals on the ramps. Well good/bad ideal, probley got a cold sodder joint on the wire ends and wasent getting good voltage to the D8 line. Worked for a while but after heating up and cooling down a couple of times the sodder formed a shell around the wire end and it wasent getting good contact and a drop in voltage/amps?
At least that what I hope happened and I have it fixed, and it wasent something else and the problem will come back. Anyway did some printing this morning and it looks good
so we will see what happens from here.

Thanks to waitaki and sdavi for the help.

Until next time.

I'm having the exact same problem but its shuts down then i turn my hotend on. I think the problem might be in the power supply which is 5A and arduino has 5A and 11A input,i'll try to switch to 15A PS and se what happens.

The funny thing is that im now having this issue although it worked fine with exact same setup for a year.

I had power supply problems with the heated bed. I was using a "12Amp" power supply.

Printing was fine, but when I switched on the Heated bed, it would immediately switch back off (even with the hot end off). Then after many tries, the HB would cause the whole thing to power down (inc. ramps). Then I found I could heat the hot end, then switch on the HB and the HB would work (with VERY hot yellow fuses on the RAMPS) - which is odd as I was using more power than with the hot end off.... anyhow..

It turns out my PSU was rated at 12Amps "Duty cycle" - i.e. in bursts. In reality it's a 7Amp continuous supply.

I switched to my monster 30Amp unit , which has a meter on it and everything worked perfectly. The whole rig draws 9 amps with the HB on and printing. Oh, and the fuses on the RAMPS now run cool.

Mine all worked fine for a few days before any problems started. I am assuming the power supply degraded a touch, or something on the RAMPS became less tolerant of low current over time.

So the moral of the story is make sure you have a decent enough power supply!

Edited 1 time(s). Last edit at 04/09/2014 07:10AM by Dodgey99.