M1 current sharing between nozzle and bed

[Scott]

Hello

I have an M1, and I am trying to print ABS for the first time. I try to set my bed temperature to 110 C, and with the nozzle off, I get to about 102 C. As soon as I heat the nozzle, however, the bed temperature drops to 82 C. It seems a little like I am having trouble sharing the heater current with the nozzle. Has anyone else had an issue like this? Any fixes?

Scott

[Joshua Wills]

How do you have your power supplies connected?  I'm not certain about different revisions of the kit, but you should have received two separate power supplies, one 12V laptop style and one 24V open-frame.  The 12V should be connected to "5A" on RAMPS, and the 24V should be connected to "11A".  The HBP is the only thing that is powered from the second power input.

[Scott]

I do have my power supplies connected as you mention. I also have a work fan connected to D9 (extruder on D10, HBP on D8). When I disconnected the work fan, the HBP gets to temp and does so much faster. That must have been the problem. So is there a better place to connect a work fan?

[Triffid Hunter]

On Mon, Sep 10, 2012 at 9:24 AM, Scott <scott.k...@gmail.com> wrote:
> I do have my power supplies connected as you mention. I also have a work fan
> connected to D9 (extruder on D10, HBP on D8). When I disconnected the work
> fan, the HBP gets to temp and does so much faster. That must have been the
> problem. So is there a better place to connect a work fan?

sounds like your fan had a short. A standard computer fan takes so
little current compared to the heaters as to be totally
inconsequential, unless it has some sort of fault. I'm surprised
something wasn't melting

[Scott]

Sorry it has taken me a while to do the checks.

The cooling fan shows 23 kOhm, which seems pretty reasonable to me. I checked that the 24V power supply is connected to 11A and the 12V laptop supply is connected  to 5A.

The HBP looks like it is about 6 Ohms, so draws 4A or something from the 24V supply? Does that sound right?