Re: Melted Terminal Block for Heater Bed
Erron
That looks very much like a cable management issue - did you cable tie at the entry to the RAMBo housing to prevent cable movement?
Peter
It looks like that cause i have everything unpluged from the rambo (pulled it out to get a better look) , and everything was indeed cable tied, and there was no movement of the connectors plugged into the board during printing
In regards to the version number, Looks like 1.3a
I'd like to get the headbed running ASAP, and i know Josef was advising to solder the to solder the headbed leads directly to the back of the board. I'm no expert at soldering, (but i have all the equipment) if anyone is willing to offer some tips or pointers on how to get it done. I'm assuming you need to desolder and remove the connectors on the board first?
Re: Melted Terminal Block for Heater Bed
Erron
Yes, soldering is the next suggestion. No need to desolder the connectors, just strip the wires back 3 to 4 mm and using flux and solder (or multicore solder), make sure you time the ends of the wire completely.
Then place the wire on top of the solder pad underneath the board, press the soldering iron onto it for a couple of seconds and make sure the solder flows between wire and pad to make a good mechanical and soldered connection.
I guess the board is made using lead-free solder, so you may need to heat the solder pad and apply a small amount of your solder first.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
Erron
Yes, soldering is the next suggestion. No need to desolder the connectors, just strip the wires back 3 to 4 mm and using flux and solder (or multicore solder), make sure you time the ends of the wire completely.
Then place the wire on top of the solder pad underneath the board, press the soldering iron onto it for a couple of seconds and make sure the solder flows between wire and pad to make a good mechanical and soldered connection.
I guess the board is made using lead-free solder, so you may need to heat the solder pad and apply a small amount of your solder first.
Peter
Thanks! sounds easy enough.. didn't wanna have to solder the Extruder lead too 😛 if i didn't have to. Sounds great.
Re: Melted Terminal Block for Heater Bed
Stay clear of soldering the extruder cables. I think they may be a steel wire and there not solderable. In any event, the extruder only requires 20% of the current that the heated bed requires, so should not be an issue.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
Stay clear of soldering the extruder cables. I think they may be a steel wire and there not solderable. In any event, the extruder only requires 20% of the current that the heated bed requires, so should not be an issue.
Peter
Does it matter which lead goes on which pad? i know it didnt seem to matter when i was putting them in the molex connector?
EDIT: And i really appreciate all the advice PJR!
DOUBLE EDIT: I went back and read the instructions, and it said it didnt matter. Got everything soldered up and reconnected, and i have a working heatbed again! Thanks guys.
Re: Melted Terminal Block for Heater Bed
Awesome. Good luck printing.
Re: Melted Terminal Block for Heater Bed
just adding a "me too" note here- I experienced similar meltdown, as described earlier in this thread.
took a few hours & tries to unbuild the rambo-box,, successfully solder heatbed wires to the rambo backplane, & reassemble.
I used a ziptie thru the project box's now-unused heatbed-wirehole, for strain-relief, & to guide the hotbed cables from getting stuck on the back corner-edge of the y-axis assembly.
hotbed rises to 50 much faster now. 😳 
Re: Melted Terminal Block for Heater Bed
can you post a picture of your solder joint please?
Re: Melted Terminal Block for Heater Bed
just adding a "me too" note here- I experienced similar meltdown, as described earlier in this thread.
took a few hours & tries to unbuild the rambo-box,, successfully solder heatbed wires to the rambo backplane, & reassemble.
I used a ziptie thru the project box's now-unused heatbed-wirehole, for strain-relief, & to guide the hotbed cables from getting stuck on the back corner-edge of the y-axis assembly.
hotbed rises to 50 much faster now. 😳
Yup, and im guessing my original issue was probably under tightening the heatbed connector, ive been running my second machine that i built last week almost non-stop for most of the week, and no issues at all. And i know i tightened that heatbed connecter till my hand hurt 😛 (will report back if anything changes.
Re: Melted Terminal Block for Heater Bed
Hi soldered a new heater bed to the Rambo and here are the images. Unfortunately I am not seeing any faster heat times yet
Re: Melted Terminal Block for Heater Bed
Hi Tim
Can't remember if you have posted this before... Can you please advise what your bed heater resistance is and also the voltage across the bed terminals when heating?
Thanks
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
I have a brand new heatbed which is different than the original one I had. I realized that there are 2 negative terminals on this board so once I soldered that on the bed heated up very nicely. Each of the terminals is for 1/2 the board so you need to connect both. This board also has a nice blue led which I like to see.
Re: Melted Terminal Block for Heater Bed
Tim
As you probably know, most heated beds have this arrangement as they will work on both 12 and 24 volts. If you have not wired it properly, then it will not be hot very quickly. I can't help very much unless you answer the questions... What are the readings for resistance and current?
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
Yes I realize there are two. Right now I think I have solve the heat bed issue. It is responding very well. Thanks for the help.
Re: Melted Terminal Block for Heater Bed
Tim
Looking again at your photo, it seems that you may not have wired it properly for 12 volts. Solder pads 2 and 3 need to be connected.
Peter
P.S. It would be good if you could post your fix online as it may help others.
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
Yes the image was wrong and as a result only 1/2 of the plate heated. Once I connected the 2,3 connector pads 100% of the bed heated - and quickly.
Re: Melted Terminal Block for Heater Bed
Tim
That's great news. Tanks for letting us know.
Did you get your other issues from last week resolved?
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Melted Terminal Block for Heater Bed
Sadly I have not.
I am still having trouble printing but now I have eliminated the bed problem.
PLA is just plain difficult so I am now going to attempt to print a test object using the last remaining ABS filament I received when I purchased it. I will resume that discussion on the thread "No Luck Printing Anything"
Re: Melted Terminal Block for Heater Bed
Hi
I had the same issue with a melting terminal. Not sure yet, how I will try to fix the problem.
A general solution for a future printer update, could be to use 24V for the heatbed.
The heatbed PCB would need a redesign but the contact resistance at the terminal would have less influence on the whole heating circuit.
For the same heating power only half the amps would be needed and therefor less power loss would occur at the terminal connector.
greetings from Bavaria
Re: Melted Terminal Block for Heater Bed
Not only the terminal, but also the FET burned out. Lukely I was near the printer and the house was not on fire.
This happens within the first 24h of operation.