MKII Heatbed Issue: Turns off

Hey all,

I've got a Issue with my MKII Heatbed: It's heating about 30 degrees, and then it turns off. (Voltage Drop from 11.85V to 0.3V) everytime. Doesn't matter if Printing or just Heating. I'm using two ATX Power Supplies. 19A+16A.

Software:
Sprinter FW
Pronterface

Hardware:
RAMPS 1.3
Prusa Mendel
DELL Power Supplies.

Could be your thermal fuse the big flat orange looking thing standing up on your ramps. It basically a self resetting circuit breaker if you pull to many amps it gets hot and trips. Mine would trip when I would first try to heat the bed after I put a fan on my ramps it has not kicked out since.

So, maybe it can be solved when i swap the two fuses or install one with more amps?

It would probably be safe to change the bigger one to a 15amp replaceable fuse. The stock is 11amp and the mkII draws really close to that on heatup I would try a fan first just to see if thats the real problem it if it is then replacing the fuse should fix it.

I would guess that your PSU is cutting out because the draw is too high. I would try a new PSU with a higher rating and not touch the fuses.

---

FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

I will try now PSU's with higer rating and check the fuses. If i power it directly from a ATX, and put another ATX at the Ramps, it work too.

Or another idea:

how thick are your bed cables to the ramps?
Maybe its requiring too much amperage and your cables may be too thin to withstand a prolonged heating (high amperage)

Just some thoughts because I had a similar problem with the heating bed before and the extruder as well...

try using thicker cables. I use 18 gauge stranded, but you may use a bit thinner if it works for you. I just wanted it to warm up as fast as possible.

cheers and good luck