Hot bed freezes pronterface

Just assembled Mendelmax 1.5, I have a 30a 12v power supply, voltage drops to 11.5v when I turn on heat bed then creeps back up to 11.98v by my meter but pronterface freezes and I can't print. I was able to make test print using car battery as power supply and was successful until the ABS print came off and I stopped print. Car battery puts out 12.6v at start, 12.1v when I stopped printing. I haven't smoked any electronics yet, would rather not, I was thinking I could tweek the output of power supply to 12.15v maybe higher if I still have issues. Is the a bad idea? Or any suggestion of a better idea?
thanks for your time, Kurt

Edited 1 time(s). Last edit at 03/23/2014 02:57PM by K.

I would think your power supply is alright as it is. Have you checked the resistance of the heat bed and are the heat bed cables thick enough for the current?

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Waitaki 3D Printer

1.4 ohms heat bed resistance, for the power cables I was a little goofy and made a multicable 6 strands for each leg using the wire left from wiring the motors, I will just go ahead and swap that out, would 14 gauge be right?

I have replaced wiring to heat bed, still freezes, I am bummed, meter D8 I get 11.3v, I was measuring at power supply before

I forgot to mention... If you are using a PC power supply, you will need to put a load on the 5v rail (say, a 5 watt resistor or something) otherwise your PS will probably play up.

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Waitaki 3D Printer

Is it Pronterface that's frozen, or is it that your connection to the electronics/USB is dropping and disconnecting?

I'd check that you get clean, solid supply to the logic side of your electronics. If your electronics are something like [reprap.org] , you might add a capacitor between VIN-AM and ground, or maybe one of the alternate powering suggestions there.

If you are losing USB connectivity, check that your logic-side power isn't noisy.

Pronterface has error messsages if I unplug USB so I think it's still connected , controls don't work and have to uplug to turn bed off
I have a plotter with "special" USB cable tried that and different computer
Have already swapped out power supply for identical, the one I returned checks out ok,,
it works on a car battery so I really want to blame power supply anyway,,,, what have I done different my setup?
Have a to find pc power supply I can pull, , will try that next, thanks for the 5v tip

Edited 1 time(s). Last edit at 03/25/2014 09:25AM by K.

Is pronterface really frozen, or is it waiting to push other commands into the electronics.... maybe see if you can toggle the 'Watch' control or clear the output log. You could also start up another pronterface or try to connect with pronsole ot Repetier host or something to prove if its Pronterface or your electronics that's frozen.

The car battery would give very clean, strong power, so I'd guess it must have something to do with getting the power out of your 12V 30A supply and into your ATMega. Swithicng powersuppys can have lots of high frequency ripple and noise, which won't bother the power-hungry heaters and stepper motor coils, but could possibly affect the ATmega logic and the stepper-drivers.

With RAMPS-like electronics, you could hook your battery up to the 12V 5A side, and the 30A supply to the heatbed side.

Edited 1 time(s). Last edit at 03/25/2014 11:06AM by DaveX.

new power supply, stayed connected after bed heat for maybe 4sec then lose connection, as I think now, frozen screen,,,,
quite a while later with different USB cable and using different USB jack I was able to print!