PSU connector got melted....

Hi,

I am using following in my 3D printer.
Arduino MEGA2560, RAMPS 1.4, ATX PSU, Marlin firmware, 300x300 heatbed.
Yesterday when I started the printer, I felt something burnt & that was the PSU connector which is connected to RAMPS.

What could be the reason for this?

Anybody had such issue??

I am using large heatbed without any relay. Is any relay necessary to fetch correct Amperes for large heatbed?

Regardss,
Prashant.

That's a common point of failure. There is an awful lot of current passing through that connector. The one that came with my ramps was rated at 10 amps, but the heated bed can draw more than that. Of course, any electrical connection is going to be at its weakest where there is a connection.

I've since replaced my connectors with one that is rated up to 15 amps. I think I got them from mouser, but I don't have a link for you. It's not foolproof, but I'm hoping it's just a bit better. Also, it is VERY important that the wire be proper gauge (at least 20, perhaps even 18) and that you screw it down as tight as you can possibly make it.

I have the same Arduino and Ramps as yours. I used heavy duty wiring for the bed heater but the Arduino board used to run very hot due to the amps going through it. After I fitted a solid state relay for the heat bed, it now runs very cool.

@ dave3d, can you tell me how & where did you fitted the solid state relay, preferably a ckt diagram??

I have one lying idle at this moment, but I don't know how to use it. (12 Volt PCB Mount Relay - 30 Amp)

That would be very kind of you...

Regards,
Prashant.

Hi Prashant, there are only 4 wires to the solid state relay. It is not rocket science.

2 wires go fom the Ramps/Arduino bed connection output (D8) to the relay input so the relay switches on and off as required. I then wired a ground lead from the PSU direct to the bed and a +ve 12v supply from the PSU through to the output connectors on the relay to the +ve connection on the bed heater. Just pay attention to which one is +ve and which one is -ve. It is as simple as that.

The relay needs to be dc not ac. The spec on mine is:-

Fotek SSR-40DD
40 amp rating
5-32v dc input
5-110v dc output

I ordered it on Ebay from China. Got the idea from this forum.

[www.ebay.co.uk]

I mounted it on the back of one of the uprights on my OrdBot. Kept it close to the Ramps board to keep the wiring as short as possible. Works very well. Previously I used an ir gun and it was 150 deg C+, now cool enough to touch.

Edited 1 time(s). Last edit at 10/09/2014 01:37PM by dave3d.

Hello Dave3d,

Thanks for the info...

Mine relay is 6 Pin, DT90-1C-12VDC, (2 terminal for C, 2 for coil & 1 each for NO, NC)

NO : 30A 250VAC,

NC : 20A 250VAC

[doat.co.in]

It didn't specified much details but similar to [www.mouser.com]

Regards,
Prashant.

SevenSwitch is a design crafted with RepRap controllers and heated beds in mind. Easy to make and even buyable assembled.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

Prashantdshinde, I have the same relay setup as dave3d and I really like it, All the wires and connectors are now cool to the touch. I originally intended to use an automotive type relay that was electromagnetically operated but was advised against it on this board due to the fast cycling the bed relay goes through. The light on the solid state relay sometimes looks like a Morse Code reader it flashes so much. My bed can pull up to 19 amps which could be a strain on a mechanical relay cycling that fast.

Hi Dave3d, Airculd,

I made the relay circuit as per the image shown in - [www.makerfarm.com]

I hear the click sound when I turn ON the heatbed in Pronterface, But the heatbed is not getting heated.

Any suggestions please.....

prashantdshinde,

I cannot comment on whether your relay is suitable. It sounds as though it is if it has a 12v dc coil.
If it clicks it must be pulling in I think. Can I suggest you put a multimeter on it to check the output connections are correct and they are switching.

As Airkuld said, an electromagnetic relay is not ideal. You are better with a solid state relay. The one I use cost just 4.33 GBP.

@ Traumflug,

I have assembled a seven switch 1.2.

Con1 is PSU +12v,

Con2 is.....? I don't understand what /where to connect this?

Heater is heatbed connector. But both pins of Heater connector shows 12v & 11v resp. Please clarify.

Please correct me if I am wrong.

If you can show me some images with all connections on ramps1.4 that would be very helpful

Regards,
Prashant

Conn2 is the pwm control signal from your main controller board, I'd assume coming straight from a pwm able pin of the micro controller there.

More details here : [reprap.org]

Edited 1 time(s). Last edit at 10/23/2014 08:41AM by DeuxVis.

---

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Remove those connectors and trash them, I have gone through two sets, one came on the board and the other was a "quality" set. Both burned out, so I went with what I know, I got some EC3 RC battery connectors. They are rated to between 40-60A and I no longer have to deal with the thermal expansion causing my heated bed connectors to loosen.

Replaced 4 pin terminal blocks.