Heatbed will not heat to 110

I’ve been printing with , pla filament, for over a year. Works great, have no problems.
Decided to try printing with, abs filament. The heat bead would not heat up, which I was told probably was the, mofet, that was no good. So I deicide to change the, Ramps 1.4 board.
The problem now is the heat bed will heat up, but will not go any higher then in the high seventy degrees’ and then settle back to the low seventy and stay there.
I use Slic3r and Pronterface.
Printer is; Prusa i3
Mega 2560 R3 control board
Ramps 1.4
12 v - 15 amp power supply

Edited 1 time(s). Last edit at 05/30/2015 08:46AM by tobig11.

Might be the power supply.
Most people run 12v 30amp PSU's

Is the thermister configured for the correct one in the firmware? I'm still kinda new to this arena, so if I'm wrong or way out in left field please disregard. I have heard of MOSFET issues, but I've not had to deal with them yet.

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Floyd
Might be the power supply.
Most people run 12v 30amp PSU's

The heatbed usually only draws 8A. But it is a good idea to check the voltage at_the_bed-solder_terminals. Maybe the cable is too thin?

Which heatbed do you have, is it insulated from below?

What is written on the MOSFet? ( Q3 especially ) Does it get hot?
-Olaf

Edited 1 time(s). Last edit at 05/30/2015 11:52AM by o_lampe.

The headbed is a mk2a. Change the wire to the thermistor to a thinner wire. This got me to 90 degrees. I quess, next I will get something to insulate the bottom of the bed.
To me I would rather print with PLA then ABS. ABS is more durable then PLA, butis easier to work with and don't smell. May in time when I work with it more I will like it better. The biggest dislike for me is trying to get it to stick to the bed.
Thank and have a good day, Ed

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tobig11
Change the wire to the thermistor to a thinner wire. This got me to 90 degrees.

Wow, what is the science behind this?
It sounds, like you are only cheating yourselve.

Sorry, don´t take it pesonal
-Olaf

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o_lampe

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tobig11
Change the wire to the thermistor to a thinner wire. This got me to 90 degrees.

Wow, what is the science behind this?
It sounds, like you are only cheating yourselve.

Sorry, don´t take it pesonal
-Olaf

The science behind this is the one, I had on the printer is one I made up. The one I just put on the printer, Is a premade one, made for the printer. So how am I cheating myself? So anyhow I now setup the themistor center under the bed, which I can get the bed to 110 deg, if I want to wait for it. I set the bed temperature to 100 deg, which works fine when printing, so it will shout down sooner. I have order insulation for the bed, when I get it I will reset the temperature.
Thank you, Ed

Edited 1 time(s). Last edit at 06/01/2015 08:28AM by tobig11.