Heated Bed Connector - Burned Crispy :o(  

Re: Heated Bed Connector - Burned Crispy :o(

Usually the RAMBo connector is also toast.

Replacing the connector is not easy; much better to solder the cables directly to the underside of the RAMBo

Peter

Re: Heated Bed Connector - Burned Crispy :o(

Yes, both the plug and socket are Molex and yes, they can pass 18 Amps without issue.

The problem occurs because of other issues, such as poor cable management or connection not properly made. However, the problem can also occur apparently for no reason whatsoever and has been present since the Mk1 was released, well over a year ago.

It has also happened to me after using the Mk1 for 9 months. And when it happened to me there was a reason (mentioned above) despite the fact I was well aware of the potential issue, I was simply careless.

Peter

I wasn't aware this problem already longer exists. I just build mine and will try it for some time with the connectors. But, when it functions good and I think I don't need to take it apart anymore I will solder the cables to the RAMBO.

Re: Heated Bed Connector - Burned Crispy :o(

Fixed mine:

Solder+silicon to hold.
I was a bit scared but with no other solution available I did it.
So far so good I'm back in business 🙂

Re: Heated Bed Connector - Burned Crispy :o(

Did anyone ever actually get contacted back by customer support on this issue? I have been running a MK2 for over 10 months with no issues until now.

I am a complete novice at best, and really need some help walking through this.

Re: Heated Bed Connector - Burned Crispy :o(

My printer had been sitting there not used for about 7 months. i just tried to get it going and as soon as the bed started heating up the same thing happened to mine.....how did this turn out? did you get it fixed? I dont know enough about this stuff to fix it....

Re: Heated Bed Connector - Burned Crispy :o(

I claim the screws are tightened too tightly and the connector rotates in the housing. You can often see this on the pictures, the plug hinges are always deformed at the sides. Normally these plugs are not very tightly screwed (5 lbs in).

Re: Heated Bed Connector - Burned Crispy :o(

sadly, I've joined the club. After about six months of use, I got a thermal runaway error yesterday, and couldn't get the bed to heat up afterwards. The thermistor functions, no loose cables, but a connector that wouldn't budge. After some careful prying I got it to come loose, but it suffered from serious heat. The screws aren't on the terminal aren't loose. In fact, I haven't managed to unscrew them yet...

Is getting out the soldering iron the only way to go? By the way, all wire harnesses were assembled as per the manual.

Peter

Re: Heated Bed Connector - Burned Crispy :o(

Is getting out the soldering iron the only way to go?

No, but it's by far the best way to go. Maybe solder some heavy duty wire tails onto the RAMBo and then add a pair of these (or similar): https://www.banggood.com/5Pcs-235-Pins-Reusable-Spring-Lever-Terminal-Block-Electric-Cable-Wire-Connector-p-1103030.html?rmmds=flashdeals

Peter

Re: Heated Bed Connector - Burned Crispy :o(

No, but it's by far the best way to go.
Peter

Thanks for the swift answer. I'll look into the possibilities of repairing the wires myself, but as the machine is less than a year old, everything was assembled as per the manual, and the machine was used within the prescribed parameters, I'm sure this problem should be resolved under warranty.

Re: Heated Bed Connector - Burned Crispy :o(

Hi!!

Today i got the same problem, printer stopped while i was at work.

Found this.

Did some research on the forum and noticed that everybody who had this happen to them
seem to have the same problem and its not that the cable management is not correctly done, the problem is that the
cables are too short and strains the connector.. look here

If you look closely you see that the cables going to heatbed are too short and pulls on the connector up and to the back, a few
cm longer cables and maybe a zip-tie, this problem would be solved.

I contacted support chat but they dont give a shit, they just told me its my problem and to buy a new connector even if i
tried to explain why this keeps happening again and again.

I have been working as an electrician more than 10 years and i am confident that this problem
would be solved with longer cables.

What do you guys think?

//Kimmo

Re: Heated Bed Connector - Burned Crispy :o(

Hi!!

Got mail from prusa today, they have looked at my pictures and want to send me
a new molex connector, maybe because they see that the cables from my bed are just a little too short.

Gonna solder a piece of wire on the cables to extend them a little, or just solder some wires
to the rambo card and then connect them with the Heatbed cables..

anyways nice that they looked at my pictures and decided to help me 🙂

// Kimmo

Re: Heated Bed Connector - Burned Crispy :o(

Hi,

+1.

Start to smell this morning...Might be from my last print, a big object, forcing the bed to travel almost entirely up/down overnight...

The molex has just started to melt...Nothing looks really bad at this stage.

Does anyone has source it from the web ?

Happy friday

Re: Heated Bed Connector - Burned Crispy :o(

Hi,

+1.

Start to smell this morning...Might be from my last print, a big object, forcing the bed to travel almost entirely up/down overnight...

The molex has just started to melt...Nothing looks really bad at this stage.

Does anyone has source it from the web ?
molex.jpg

Happy friday

From Europe or better, from France ?? I found US or China, but cost of delivery and/or delay is not compatible ...

Re: Heated Bed Connector - Burned Crispy :o(

Similar thread here that I started: https://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/problems-with-prints-resetting-then-found-burned-m-t5957.html

Re: Heated Bed Connector - Burned Crispy :o(

Thanks, but i'm not sure about my ability to solder it 😕

I ordered here : http://www.uctronics.com , and hope it won't last much to receive it !

Re: Heated Bed Connector - Burned Crispy :o(

Hi,

same problem here. It even melted the cables. My solution was soldering the cables directly to the board.

Re: Heated Bed Connector - Burned Crispy :o(

Did some research on the forum and noticed that everybody who had this happen to them
seem to have the same problem and its not that the cable management is not correctly done, the problem is that the
cables are too short and strains the connector.. look here

If you look closely you see that the cables going to heatbed are too short and pulls on the connector up and to the back, a few
cm longer cables and maybe a zip-tie, this problem would be solved.

I have been working as an electrician more than 10 years and i am confident that this problem
would be solved with longer cables.

What do you guys think?

//Kimmo

Hi Kimmo,

After months of printing, the heated bed started progressively to required more and more time to catch the 100C required for ABS printing.
I soon realized that the cable connector was getting so hot, that I could not touch it. The problem was that the internal metal part of the molex female connectors have been deformed and so they were not capable for a reliable (18A) connection. Deformed not by the heat (at least not yet) but by the permanent stress that is applied to them by the too short length of the heat-bed cables.

If the cables were 5-10cm longer then there would be no stress to the connectors and thus no problem.

The solution is, first of all to replace the cable with a longer one and:
1. If the male Molex connectors have no signs of carbon deposits on the contact area, then replace the female connector.
2. If the male connectors have signs of carbon deposits (more black than metal color), then replace both the male and female connector. Some skills are required to de-solder and remove the connector from the PCB without destroying the surrounding area.

The proposed solution to solder the wires directly to the bottom of the PCB is not the first on my list, since sooner or later, it will introduce a couple of problems (at least from my experience):
1. There is no way to mechanically hold the soldered cables in place unless someone drill the PCB and screw/cable tie ... them. So, the soldered wires will constantly apply stress to the copper bands and eventually they will detach them from the PCB. Result is an almost not fixable PCB.
2. The two cables will be soldered very close to each other. If for any reason a couple of wires from one cable are cut loose and happen to touch the wires of the other cable the rambo PCB will be destroyed beyond repair.

The only way to safely solder the cables to the PCB is to first solder appropriate pins through the PCB and then solder the cables on the pins. Don't forget to put therm-shrink tubes to cover the cable and the pin.
Since we have the male connectors already soldered to the PCB, one could carefully cut and remove the upper plastic part of the connector and use the metallic pin to solder the cable.

Re: Heated Bed Connector - Burned Crispy :o(

I had this same thing happen. Support said "Tough luck". The problem on mine was that the screw fitting wasn't made properly and even though the screw was tight, the connector wasn't and the cable worked loose over time. I fixed the screw connector, replaced the crimp sheaths on the cables, and haven't had a problem since, knock on wood.

Re: Heated Bed Connector - Burned Crispy :o(

This just happened to me a few days ago, after printing very successfully for the last six months or so. In my case, the filament being used as a cable guide broke and perhaps that allowed extra strain on the connector (this was discovered when I opened up the electronics box). I'm going to go with the soldering of the wires directly to the board. I can't find it now, but I feel that I actually read that suggestion during the assembly process, it was something they do in the Prusa factory on the machines they use to print the parts. If it was a forum post, I can't seem to find it now, but I think it was in the notes on the assembly step and I can't find that either, but the pdf is a newer version.

Re: Heated Bed Connector - Burned Crispy :o(

This just happened to me a few days ago, after printing very successfully for the last six months or so. In my case, the filament being used as a cable guide broke and perhaps that allowed extra strain on the connector (this was discovered when I opened up the electronics box). I'm going to go with the soldering of the wires directly to the board. I can't find it now, but I feel that I actually read that suggestion during the assembly process, it was something they do in the Prusa factory on the machines they use to print the parts. If it was a forum post, I can't seem to find it now, but I think it was in the notes on the assembly step and I can't find that either, but the pdf is a newer version.

I soldered the bed wires directly to the Rambo and added a couple inches to them as well. It's working fine now. It turns out that my recollection of the suggestion to build it that way was wrong. They suggested the power cables be wired that way, which is how I had done it. Probably someday I'll be soldering the hot end cables in that way. 😛