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Power Outputs Malfunctioning

Posted by Veen 
Power Outputs Malfunctioning
February 18, 2013 11:15AM
I'm setting up my first printer using the RAMPS 1.4 Board and Marlin firmware. I have all my steppers moving properly but am having trouble with the hot-end, bed, and fan outputs. They all seem to be permanently "stuck" in an on or off position. The hot-end is stuck on and the bed and fan are stuck off. It may be the mosfets and I'm getting some new ones to replace just to be sure. However, the control pin on each FET is low and only one of the outputs is still on. No matter how I toggle the hot-end or bed on or off in pronterface, I don't see any difference on the control pin for the FET. Any suggestions for what to look for would be greatly appreciated.
Re: Power Outputs Malfunctioning
February 27, 2013 08:56PM
Have you wired up both 12v inputs?
Re: Power Outputs Malfunctioning
March 01, 2013 01:03PM
I have tried both with and without both 12V inputs.

I did some further testing last night and found that the ground for the hot-end output was shorted to the board ground. Even with the FET removed it was still grounded. I also found that without any pressure on the terminal block, it was open, but as soon as I pushed on it, it shorted again. So I removed the terminal block and tested the pad, which is now not shorted. I don't really get how the terminal block could cause the short, but I ordered a new one and some new FETs. Hopefully it will all work when I build up again.
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