MK2a heatbed

Half of my heatbed dosent get very hot at all, and Ive had problems with edge lifting loose from printbed and sometimes parts come loose on the half that dosent get hot.
The other part no problem so as of now I can only print something on the hotter part of the bed.
I have the black MK2a heatbed, and Im using a Geteck 12v 29A DC swiching power supply.
And I have it wired to the no. 1 and 2 soder points for 12v.
And like stated half get hot to the touch and the other not so much.
I put some cardboard under it to try to get the temp up but it dosent help much.
So do I have a bad heatbed or something with the wiring? So I try to wire it for 24v? I wouldnt think so but am new to this.


Thanks.

Have you measured the resistance of your heatbed ? Does it heat OK if you connect the heatbed directly to your power supply (dont do this without knowing the resistance first)

Since you mentioned number 1 and 2 points for 12V, it isn't by any chance one of the boards that has 3 solder points and dual power? Could it be a MK2B?

If it has 3 solder points, do you have a table on the board that looks like this one: Reprap wiki ? If so, then you actually have to bridge the 2 negatives together (i.e. pins 2 and 3) when using 12V supply.

Measuring the resistance is a good idea. If the bed is configured for 12V, you should be looking at a resistance of around 1 to 1.2 ohm. Also make sure you are using the correct size wires to connect the heated bed, they need to be capable of carrying around 10-12A.

Yes that what I was thinking after reading some today and looking at some pics on Google images.
I have it wired from the ramps board and sodered to the 1 and 2 points, wich I understand is only providing power to half the board. So I will connect the 2 soder point to the 3 and should have power to the whole board. But what little printing Ive been doing looks good. A little more fine tuning and I should be good to start printing some of the stuff
Ive built it for. Still need to learn some more about the settings in sli3r and marlin to get good prints. More cocerned about print quality than speed. Lot to learn and have fun.

Thanks for the reply, Ill be back.

Ok sodered the no 2 and 3 points together, then insulated the bottom of the bed with cork glued on with high temp gasket sealer.
Got everything back together and a big differnce. Took the bed 30 to 40 minutes to get up to temp and only half the bed getting hot.
Now it only took 3 to 4 minutes and the whole bed hot.
What a diffrance doing things right makes.
Should be able to print some tomarow and work on fine tuning my settings.

Thanks agin for the help.