Naked Heated Bed

Hi everyone...So I recently bought a heated bed off of Amazon but upon opening the package I realized that the board was completely naked lol...no resistor or LED...So I can live without the LCD but what about the Resistor? Do I need to procure one? What is the Purpose of the Resistor on the Board????

Also I am running an Arduino Mega/RAMPS 1.4 combo and I live in the US and am running a 120 volt power supply.

I have attached a picture of my board. Should I wire my board for 12 volts or 24?????

Thanx

The resistor is for limiting the current of the led, so if you are not going to solder a led, you can also ignore the resistor since they don't have anything to do with the heated bed itself. If you want to add a led, use a 1k resistor (for 12v) and remember that leds have a polarity (the shorter leg is the negative) or simply solder 2 each in the other way.

As for the LCD it allows to run your printer standalone (without a computer, just using the lcd and a SD card to run things) so you can run your reprap without the lcd.

As for your mention of your mains voltage, STOP RIGTH THERE. every part of your printer should be wired to the power supply, wich would produce a voltage of 12v (or 24, depending on the ps, but typically 12), so your mains voltaje is only a concern to the power supply. NEVER wire mains voltage to a heated bed (unless it's designed for or, and pcb HBP are not). You probably know this already, but better warn you that to set your house on fire. And last, since your bed will be drawing quite a bit of power from the power supply make sure you power supply can deliver enough power.

Use at least 1.5mm² or 14gauge wire for the heatbed. For ABS printing use silicone insulated wire ( recommended )

Yes, for 12V you have to solder both pads to the GND cable.
-Olaf
PS: I´ve turned my MK3 heated bed upside down ( blank aluminum is on top ) The glass plate has much better contact or with blue paintertape you can print with 40-45°C on the bed.
The MK3 is the only board ( I know ) where this is helpful.

Edited 1 time(s). Last edit at 06/03/2015 04:02AM by o_lampe.

thanx for the info...as for lcd...that was actually a misprint..I meant to type LED...and as for the powersupply that was another misprint...my power supply is 12 volt

And thank you for your response as well o_lampe So I'm not sure of the guage but I do have an extra length of insulated wiring that came with an e3d heater cartridge for my spare hotend would that be sufficient or should I just bite the bullet and buy some thicker guage wiring???

Also what is this GND cable you are talking about?

Quote
swicboi
And thank you for your response as well o_lampe So I'm not sure of the guage but I do have an extra length of insulated wiring that came with an e3d heater cartridge for my spare hotend would that be sufficient or should I just bite the bullet and buy some thicker guage wiring???

Also what is this GND cable you are talking about?

The hotend cable usually has a nice heatresistant insulation, so "yes". But it is also meant to power only 40W (~3.3 Amps ) instead of 100W ( ~8 Amps ), so "no".
It might work, but I´d go for a thicker cable.

With GND cable, I meant the -cable to the heated bed. It has to be soldered to both GND-pads.
-Olaf

thanx for the advice guys...So I decided to buy some 16 guage wire and used that to hook up the bed...I had trouble getting it to turn on till I ran a PID autotune...once I did that it ran great...Though after my first print finished The bed did not power off...even after i turned it off in pronterface...I had to manually turn off the power...What could cause this????

What program do you use for PID autotuning?

Do you have this M140 S0 line in your end-Gcode?
Where did you put the cables on the RAMPS? Probably they are placed in extruder 2 (D9) now?
-Olaf

Well I know the locations are different things on different boards....but if your looking at the board with the power on the bottom right...I plugged the bed into the first 2 screw terminals from the power main..directly next to it...On my board they are lableled for the bed

would that m140 code still work in my configuration???

Quote
swicboi
Well I know the locations are different things on different boards....but if your looking at the board with the power on the bottom right...I plugged the bed into the first 2 screw terminals from the power main..directly next to it...On my board they are lableled for the bed

Bottom left would make sense...
Yes the connector is right. M140 S0 should work.
-Olaf