Ramps 1.4 thermistor pcb repair

recoush

Been looking over the internet for how to fix  thermistor inputs assuming t0 and T2 are open always reads 121 C and the the sensor works fine now that  had to pins h to use the T1

has anyone fixed the input connections before looks like they go to U1 or do most just toss and get another ramps?
Should have a Radds pcb coming soon. but i would hate to just junk as it has allowed me to get every thing working :>) 
 

Repetier

If T1 works and the others not, use a multimeter to measure the voltage goind to the arduino input pin. Since you have 2 boards in can be the AVR processor having a defect or the RAMPS board having a problem or config error.

recoush

Well that sounds more like the mega AVR and not likely the ramps board.
At one time i was trying to get 2  extruders set up but never worked so T2 was likely open back then and now T0 is open.  The new thermistor is reading ok at 95K ohm

Think i saw the thermistor short thought i had (seen a spark) when i checked the r thermistor came a part at one wire looks like the thin shrink tubing wore through then the reading went to 121C

Will add another layer over those 2 thermistor wires before i install the radds
 got lucky when i assigned  t1 pin in pins.h  printer is working. for now :>)
Thank You
recoush

Repetier

It is no problem to short thermistor cables except that firmware then shows a defect thermistor. Input works from 0-5V. But it should be set as input not output!

recoush

got the radds today so i can swap them to see if the issues is ramps or the mega. not much between the ramps and the mega looks like a resistor and a cap unless the cap is bad maybe the cause.