After printing with PETG, the inside off my Felix 3.0 looked like this. The wires for the headed bed meltdown. I use the printen for more then a year now. Printed with PLA, now problem like this. How can I repear this, and why did it melt. The tempretur I used for the bed was 55 dgr.
Not sure what heated bed the Felix has, but those connectors are not rated for very high current which probably caused them to melt. Find out what the pin spacing is on the burned one and find a connector that will replace it and has a high current rating. For 5mm spacing (I’m just guessing it’s that) try KF501’s
Order is important. It is extremely important not to occur at the same time heating the bed and the hot head. I always suggest warming up being head first and only after bed. Simultaneous heating to the maximum power causes great consumption of electrical current and obviously heating.
@Ronaldo_Oliveira agreed but he burned the bed connector rather than the power input itself which indicates a current failure only for the bed.
@Ronaldo_Oliveira If everything is correctly dimensioned and connected, it should not be a problem to heat the bed and head together, but if you want to heat it separately, you should always heat the bed before the head! Otherwise the head can burn the filament while waiting for the bed.
@Gerlinde_Habekotte The cables should get cable crimp terminals before screwing into these connectors!
Something like this: http://www.ebay.com/itm/400-tlg-Aderendhulsen-Sortiment-Aderendhulse-Kabelschuhe-Set-fur-Crimpzangen-/232232097081?hash=item36121c9539:g:Fl0AAOSw6DtYSLCC
It did melt because the connection was not good enough (=resistance) and therefore produced heat in the connector.
Isn’t it possible that there was a failure in the bed that caused excessive current draw?
@Kleinfeld_Technical Yes, if the bed has/had a short between two or more heat traces, then the resistance drops and so the current increases. It could also be a temporary short of the heatbed cables while it moves.
It could also be that those connectors worked themselves loose over the year. If one or both of them are loose, there would be arcing which could also cause this.
To help protect board I would place fast blow fuse inline to heated bed sized properly for voltage and max current draw.
These (cheap) connectors are operating close to (maybe even over !?)their rated current limits and if their contacts loosen over time, that connector will heat up a lot even to the point of burning like yours.
As suggested above, you must replace that burnt connector and then you have 2 choices:
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The simplest is to regularly check that new connector is always tightened on the wires and that it does not generate excessive heat while operating your 3D printer.
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The BEST solution is to move the heavy current switching outside the controller board by using a mosfet circuit. Just look around here, or on YouTube for circuit details and assembly videos. I would also make sure that the connectors used on that mosfet circuit have better current ratings that the ones on your controller.
@Gerlinde_Habekotte You can find the proper terminals as others are saying, but I wouldn’t do that if it were me. Doing that is tricky, and may require you to order 100 packs, as well as finding the right component and waiting. Then soldering and resoldering.
Just solder the wires to the pads on the bottom of the board. Skip the terminal altogether! It is faster, easier, and still very “right.” And you have no terminals then to melt!
@cprezzi I experienced the same problem in a cheap printer from china. Cheap connectors didn’t make a good connection.
Thanks for all your answers. They were very usefull.
I had the problem with my $1000 printer kit from a ways back. They replaced the board for me.
Those heated bed connectors are problems for many people. The wire draws a lot of power, so the wire and connector metals heat, expand, cool and contract as the power cycles. That wiggles the connectors looser and looser.
There are eyelet type connectors that you can get. You can use heat shrink tubing around the part that you crimp and solder to the wire. I do not know where to get a screw terminal for those to be used though.
The topic comes up often enough that if you can look back through this community’s posts you should find plenty of suggestions and parts lists.
I squared R losses are a kicker. Good ferrules would make a termination more reliable as would a decent sized terminal block. There’s a temptation to turn the PSU up a bit to speed the heater bed but that puts additional strain on the system. This requires careful study to make sure it can handle it. If not then maybe the board needs to be helped out in some way.
By the way, a burnt PCB can cause other problems so remove the screw terminal block carefully and give the board a good clean and inspection… Or just buy a new one. That’s the bit against my wallets religion.
Add one of these as suggested by @JP_Roy