Hot end always ON!

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Morriz
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Hot end always ON!

Postby Morriz » Thu Feb 15, 2018 5:07 am

Anyone know what is the problem with my HE280 hot end:

When I power on my Rostock Max V3, hot end starts immediately with red light ON and warming the heater cartridge.
Termistore measure right temp, but I cant stop warming the hot end.

The problem started during the start on a print, when bed was right temp and hot end was warming to reach the right temp.

I thing the heater certridge is good beacause it warms hot end.
I think the thermal safety fuse is good because otherwise heater cartridge not warm.
I think the 100k thermistor is good because otherwise display dosn't increase hot end temp.

So what is it??

Marcello

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geneb
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Re: Hot end always ON!

Postby geneb » Thu Feb 15, 2018 8:18 am

This can happen if the Kapton tape on the thermal fuse isn't fully covering the fuse body where it mounts in the cold section of the hot end. If any bare portion of the fuse body comes into contact with the hot end, it will result in the effect you describe.

g.
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Morriz
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Re: Hot end always ON!

Postby Morriz » Fri Feb 16, 2018 8:06 am

Thank you!
That was really this problem.

I moved just 2 mm on the right the thermal fuse and hot end and red led went OFF.

Stange but true!

Marcello

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geneb
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Re: Hot end always ON!

Postby geneb » Fri Feb 16, 2018 4:10 pm

\o/
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Jimustanguitar
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Re: Hot end always ON!

Postby Jimustanguitar » Fri Feb 16, 2018 4:34 pm

geneb wrote:This can happen if the Kapton tape on the thermal fuse isn't fully covering the fuse body where it mounts in the cold section of the hot end. If any bare portion of the fuse body comes into contact with the hot end, it will result in the effect you describe.


That kind of a short doesn't bypass the fuse, I hope...

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geneb
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Re: Hot end always ON!

Postby geneb » Sat Feb 17, 2018 11:01 am

The fuse is thermal Jim. If it gets too hot, it will do its job and die. :)

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Jimustanguitar
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Re: Hot end always ON!

Postby Jimustanguitar » Mon Feb 19, 2018 8:24 am

I wondered if the heater would pull ground through the metal can regardless of whether the fuse was open or not... That's what I was getting at.

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geneb
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Re: Hot end always ON!

Postby geneb » Mon Feb 19, 2018 9:03 am

I don't think so. It's my understanding that the hot side is the common plane, not ground. (ground is switched...)

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