Help! my heat bed not work well

Hi.
I receive my printer 2 days.
In first day .. all function work well, But I have no time to try it.
But the second day - today,
My heat bed can't work well.
When I set the heat bed temp to 80 degree.
It'll heat to some degree and start cool down.
I can only heat every 5 degree.
Like set the temp to the 50 degree ,when it reach 50 degree. I can set to 55 degree, when it reach 55 degree I set to 60 degree.......to 80 degree.
But when I start print..It'll cool down after a while.

How can I fix it?

 

You may not need to rise up heated bed temp as 80 degree,lower a bit,try 60.

 

Thanks for answer my question. I try the PLA today. It's more easy then ABS.
but I have many ABS filament. this is not my only printer. I have a ABS only printer.
So I hope the heat bed can work.
Thanks robo3d team.

 

I've got a probable solution for this problem but I won't be able to test until this weekend:
http://www.amazon.com/Sunkee-Solid-...e=UTF8&qid=1384276112&sr=8-1&keywords=ssr+vdc

This should take the load off of the RAMPS board and prevent the overheating that seems to be a frequent occurrence.

 

Leon,I have tested some relay like that,it doing very well.This can really solve the problem.
It makes power from 350w power supply directly,the RAMPS board becomes a controller to send signal,it will not heat itself anymore.

 

I "Think" I am having the same , if not similar issue. Originally, my heat bead worked fine... for months. Now, It will turn on when I first start it up, but after 5 minutes, it quits heating. The Software is still calling for heat, but the bed just cools down. I turned the printer on its side and watched the two red lights. The top one (closest to the terminals for the bed/extruder) flashes at varying rates and is the control for the extruder. The lower Red light comes on at first, then off once the bed gets to temp, then on and off a few more times regulating the temp, but after just a few minutes, the red light just stays off.... And the bed cools down.

 

Sounds like the polyfuse is latching open killing the heatbed.

I replaced my polyfuse rated at 11A with one rated at 14A. So far so good but I haven't done extensive testing to know if it fixed the shutoff problem. The other alternative is a relay bypass circuit. You can get a 25A ssr for 15 on amazon or 2 for the polyfuse.

 

hi, I'm not an engineer or technician, i have the same issue with my printer that arrives 4 days ago. Up to now i not had any problem, but to use my ABS supply the bed must to be 100 ºC and then the temperature of bed start to cool down, even if i try adjust by the software, how can i fix that without open the printer and weld or switch any electrical component? If not possible, could you provide a step-by-step guide with pictures thats show me how to fix that? I'm noob here, thanks in advance!

 

I would love to just change the "polyfuse". Can you help me know where it is mike?

 

i have no ideia how to do this or if it is linked to the issue...

 

@Caio it sounds like your best solution would be to print a ramps fan holder and blow air on your board to keep the polyfuse closed.

What happens is the polyfuse heats up and the rated amperage decreases. So a polyfuse rated at 11A @ 25C might only be rated at 8A @ 80C. This is below our boards amp draw of around 9A, leading to the fuse tripping open. Keeping the polyfuse cool will keep it operating normally.

@John

If you have basic desoldering skills it was a pretty quick job.

From the Ramps 1.4 Wiki page



Per this schematic it's on F2

You can use RGEF1400 in place of the MFR1100.

Tessarect took a bunch of pictures of his replacement and should be posting a tutorial soon.

 

BTW, if you have never soldered before, DO NOT ATTEMPT THIS. Do not make this your first soldering attempt.

If you desolder and re-solder a new component and you are not familiar with the process of soldering you can really mess things up and not understand what it is that went wrong.

Soldering isn't difficult but there are gotchas if you're not familiar with the process. I've seen what looked to be great solder jobs but turned out that they were cold solder joints that caused all kinds of reliability issues.

 

Thanks Mike! i do not know how to sold so i will not do this, i solve the problem with a little fan beside the circuit, it works well, i made some pieces with the bed 100ºC. i know that is not the best way but....

 

If it works, it works

 

Hello guys. Im experiencing the same issue. Only its way worse...

My machine worked out just fine for 1-2 months. Suddenly I was starting to lose the control of the heatbed. First it happened while printing and now It cant even start. Noticed almost immediately that the fuses on RAMPS are freaking hot and tried to cool them with a hair dryer (no hate please that was all I had at that moment). After I reset the machine with the hair dryer blowing all worked pretty well. But the very second I took the blower away, the fuses were tripping and the heat bed was lost.

I checked all the machine for broken, melted or misfitted cables and everything looks fine. So I ordered and installed the G3D fan solution , see my attached file. Even with the fan solution the fuses keep tripping and my print wont even start. I am printing with PLA but im having hard time getting the plastic to stick without the bed.

Any suggestions before I solder new fuses ? And if not, what fuses shall I take (Im noob at the electric staff) ? This is truly frustrating,

Thanks in advance for any help !

Athena