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Help with J-head and thermistor not working

disneytoy

Help with J-head and thermistor not working
October 17, 2013 12:32AM

Registered: 14 years ago
Posts: 138

Mega+ Ramps+ Marlin.I had the J-head running before, but had to update the firmware.In Repetier if I turn on the hotend. nothing happens. At the bottom of Repetier, it shows Extruder: 478.00 C/Off.When I turn it on, i don't get a light on the ramps and the j-head does not get warm.

Any thoghts?

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Dust

Re: Help with J-head and thermistor not working
October 17, 2013 01:01AM

Admin
Registered: 15 years ago
Posts: 7,321

Sounds like a short in the thermistor or cables. Unplug the thermistor cable and measure the resistance...
Should be about 100k at 25c.

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disneytoy

Re: Help with J-head and thermistor not working
October 17, 2013 01:54AM

Registered: 14 years ago
Posts: 138

I'm reading about 70k and its around 15C room temp now. So it may be the firmware?

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Dust

Re: Help with J-head and thermistor not working
October 17, 2013 06:53AM

Admin
Registered: 15 years ago
Posts: 7,321

Could be firmware, as in wrong thermistor tables or type.

Could be a faulty ramps, there are a few components... Could be faulty ramps ADC pin.

Swap the HBP thermistor cable with the hot end thermistor cable, Does the fault move? or stay? (now put it back before you forget)

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nophead

Re: Help with J-head and thermistor not working
October 17, 2013 10:04AM

Admin
Registered: 19 years ago
Posts: 7,883

At 15C the thermistor should measure well over 100K as it is 100K at 25C and has a negative temperature coefficient.