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Shorted Thermistor and Resistor

Posted by c3opti

c3opti

Shorted Thermistor and Resistor
May 16, 2013 07:43PM

Registered: 11 years ago
Posts: 18

I accidentally had contact between the thermistor and resistor wires on my ramps 1.4 board for the hot end. I know that that damages the board and it has prevented these two connections from working. I switched the pin settings in the firmware so I can still make it work, but I was wondering if anyone knows of any way to fix this issue so that I can add a second extruder and/or a heated bed?

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antimix

Re: Shorted Thermistor and Resistor
May 24, 2013 12:40PM

Registered: 11 years ago
Posts: 65

Hello,

I am seeing a lot of those incidents, where 12V hits the 5V input. They seems very common.

Is there any voltage-regulator circuit or fuse that we can mount on the 5V Diode input signal to limit or block voltage over 5V ?
I would add to the standard design of the reprap.

Regards

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nophead

Re: Shorted Thermistor and Resistor
May 24, 2013 05:19PM

Admin
Registered: 17 years ago
Posts: 7,881

Not without affecting the accuracy of the reading. The protection needs to be between the pullup resistor and the MCU. See the discussion here: [forums.reprap.org]