[Swansea Hackspace] REPRAP question - Yellow Fuses on RAMPS board overheating

[Richard Morgan]

Hi All,
I have a problem with my 3D printer and I hope you can help.

*Blowing on the Bed*
When I start a print the bed begins heating and gets as far as about 50
degrees the stops and cools down again!

Speaking with Ceri, he suggested it might be the big yellow fuses on the
RAMPS board tripping out. I tested this by 'blowing' on the fuses while
it's heating up and 'bingo' Ceri was right.

*Fitted a Fan*
So, I fitted a 40mm fan (wired to the D9 point) over the RAMPS board to
cool it down (as it doesn't look that cool to be blowing on your board when
people see you printing!). I added the "M106 S255 ; Turn on RAMPS Board
cooling fan" code in the 'start G-code' section of Slic3r to start the fan
when it goes to print.

*Remaining Problem*
Problem still is that the fan itself doesn't actually start (i.e. this
command doesn't execute) until the bed has heated to target temp first -
which is where it trips out the fuse. This means that I STILL need to
'blow' on the board until the bed has reached target temp and then the fan
kicks in and cools the board itself fine!

So short of wiring the fan to the yellow and black power on the board
(rather than to D9) so that it's always on - is there another way to fix
this problem please?

All help very gratefully received :-)

-- 
Kind regards,

Richard
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