Step 10.76 — Thermistors at room temperature¶
Step 77 of 80 with a helper · Chapter 10 — Wiring and Checkpoint #1
(no image — see text)
Parts:
- multimeter on Ω · tool
- room thermometer · tool
Do:
- Leave the bed thermistor plugged in; write its 10.44 reading in the table.
- Skip the hotend and chamber thermistors: the toolhead closed at 10.58, and Ch 13 reads both.
Check
Read your room temperature, then compare against Klipper's own curve for that part:
Helper Records the room temperature and copies the 10.44 bed reading into the table.
What you're looking at
A thermistor is a resistor whose value falls as it gets hotter; all three of this machine's are the same ATC Semitec part, nominally 100 kΩ at 25 °C. Measuring them cold catches a crushed or broken lead before any heater runs.
Within ±15 % of the row for your room is fine. 0 Ω means a crushed lead; OL means a broken one or an unseated crimp.
Derived from the [thermistor ATC Semitec 104NT-4-R025H42G] definition in Klipper's temperature_sensors.cfg (100 kΩ at 25 °C), which is the curve the printer will actually use.
| Room temp | Expected resistance |
|---|---|
| 15 °C | ≈ 162 kΩ |
| 18 °C | ≈ 140 kΩ |
| 20 °C | ≈ 127 kΩ |
| 22 °C | ≈ 115 kΩ |
| 25 °C | ≈ 100 kΩ |
| 28 °C | ≈ 87 kΩ |
| 30 °C | ≈ 79 kΩ |
Source: Klipper temperature_sensors.cfg · LDO wiring guide § Connecting build plate