GT2560 burnt heatbed socket

[DQW]

Hello guys,

After been able to print decent from January on I've stumbled on a serious problem. Today I printed a standard print.
Only thing I did was bring the temperature up from 65 tot 69 degrees celsius to avoid warping on a big flat piece I was printing.

Until I suddenly started to smell something that wasn't the filament being extruded. After a short while I suddenly saw smoke coming out of the top of the mounted GT2560 board.
I immediately shut off the printer and felt the board motor drivers, because I thought I saw the smoke coming from there. They weren't that hot at all.
Then I started looking at the plugs of the heating and saw that my heatbed plug was burnt thru. Detailed Picture attached.

Now I can't remove the socket anymore unless unsoldering it. The wires got of the socket.

What do I do know and what do I fix?? Oblivious now for the moment for what to do. Ofcourse I want it fixed as soon as possible.

Do I need a new board, or just desolder that component use the unused socket next to it and put it in place? And how can I prevent it from happening again!

[Mark]

might be the poor quality of the plug, you can use a better plug to replace the current one. And how's the bed resistance? usually it is about 1.2-1.5ohms, if it's too low then I think the plug will not bear the high current.

[DQW]

might be the poor quality of the plug, you can use a better plug to replace the current one. And how's the bed resistance? usually it is about 1.2-1.5ohms, if it's too low then I think the plug will not bear the high current.

Where do I find better plugs? And how do I measure the bed's resistance? (without it smoking again?)

[Mark]

uh..maybe like you said, use the unused one, not all the plugs have a bad quality. And the resistance, don't need to power on the bed, just use a multimetre to check it. you can check out this link:
http://www.geeetech.com/forum/viewtopic ... 19&t=17039

[DQW]

So I've tried to measure the bed's Ohm's but I got 1 or 0. So I might be measuring it faulty. I looked at the thread u have shown me.

I've set my multimeter on 200 ohms(the ringer) and tested both sides of the heatbed 'pins'. Though mine show different pins on the one in the thread U showed me. See picture.

Another picture is the plug itself and it's burned from one side only.. maybe that tells something to. I'm now pulling of the other unused plug and then putting it back on the broken ones place.

[DQW]

I've connected the new socket in place and connected the heating bed and when manually heating the bed it gave me a red light near the socket, so the mosfet is OK.

Now the avoid it happening again, I still need to know what I have to measure exactly on the heating bed, because the thread doesn't make it clear to my which pins I should use to measure it.
As I am afraid to start it up again and have the same problem again. Could you tell what to measure exactly on the heating bed? I've used every stand from ohm's to Megaohms on my multi, but I always get 1 or 0.00 or on the Ohms stand I get a quick downwards counting to 0.

[DQW]

Well I've replaced the part and hooked everything back together. I'm at my 3th print now so far. And nothing happened.

I guess the cable pulled the socket out of the plug and made it heat up due to not being connected. At least I hope so.
Still I would like to know how to measure the bed to be sure it has the correct current running thru.

[Mark]

no need to measure the current, just unplug the heated from the socket and measure the two cables of the bed to get the resistance. And then you can use the Ohms' Law to calculate the current I=U/R.

[DQW]

I measured it and I get for the Ohms 1.6 on the lowest stand of the multimeter? So is this ok or to much?

Following question arise when I was feeling my fan for the circuit board should it blow on the circuitboard or take the heat away from it?
Because I followed the build manual on my prusa I3 and then it was set to blow away from the circuitboard (GT2560).

[Mark]

The fan should blow on the board to cool it down. And the heatbed, I think 1.6ohms is ok, not too much. Theoretically speaking, a large resistance will be more safe for your hotbed cause the current will be very small, but if too much, the temperature will not reach to the target temperature as you want.