Prusa power supply question

[HonestJohnP]

All,

I had my Prusa where the head moved along the 3 axes in the correct distances.

I had not yet connected the heated bed, thermistors, or heating element in the tip.

When I connected them, I first gave pronterface the command to heat up the bed to see if it would warm up.

the power supply immediately shut off.  The board still appears to communicate with my PC.

I shut everything off, I disconnected the wires to the heated bed and tip, and everything started back up again.

Any idea what I could have done wrong?

John

[Joshua Wills]

John, if you have the 5V load installed, the next paragraph is for you as well.  If not - try a load on the 5V rail of your PSU, anything that will draw ~500mA of current.

Andre (and maybe John) - that sounds a lot like there's a short in the HBP circuit, either on the HBP itself or in the wiring.  What's the resistance of the HBP as measured at RAMPS?

[Andre Foti]

1.2 at RAMPS...

BUT - I increased the load on the 5v Rail and now I am fine...

Thanks,

Andy

[Rick Pollack]

With ramps 1.2, how do you have the HBP wired?

--
Rick Pollack
MakerGear
23632 Mercantile Rd.
Unit D-Rear
Beachwood, OH 44122

[Jay Couture]

I think he meant 1.2 ohms measuring at the RAMPS connector. Not version 1.2 of RAMPS.

[Andre Foti]

RAMPS version is 1.4, resistance is 1.2 ohms at connector D8 on RAMPS - sorry for the confusion!

[sfisher10]

Was that the hot or cold resistance? 

[Andre Foti]

Cold, around 24C - hadn't gotten the bed to fire at the time the reading was taken.

It now works quite well, less than a minute to 60C...

If I could eliminate the lashing in the Z axis I would be a super happy camper.

[HonestJohnP]

Andre,

Thanks for chiming in.  Apologies for being out of the loop for the last few weeks. 

Are you ready for the next dumb question?

What is the 5V rail line?

and how do I increase the load on it??

John

[Triffid Hunter]

On Fri, Oct 5, 2012 at 1:35 PM, HonestJohnP <johnpb...@gmail.com> wrote:
> What is the 5V rail line?

5v rail appears between the red wire(s) and black.

> and how do I increase the load on it??

get a 12v 40-50w downlight, do this with it -->
https://picasaweb.google.com/lh/photo/DXCMfe-rdn-H1GMnmOiKGNMTjNZETYmyPJy0liipFm0
(look closely, connects to red wire side!)

yes, we are connecting a 12v light to 5v. Yes, it still gives a useful
amount of light, I use mine as a worklight -
https://picasaweb.google.com/lh/photo/U9OxeyQEzV7bmAFm5tjj3dMTjNZETYmyPJy0liipFm0

Please Note: LED ones won't work. fluorescent ones won't work. It MUST
be an incandescent type- we need that ole hot wire for this!

[HonestJohnP]

Awesome, thanks!!

John