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thermistor_troubleshooting [2016/04/16 17:18] – [Check Voltage on the Processor Pin] Traumflugthermistor_troubleshooting [2018/05/27 16:10] (current) – external edit (unknown user)
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 ==== Check Supply Voltage ==== ==== Check Supply Voltage ====
  
-Easiest way to do this is to disconnect the thermistor and measure voltage between both pins. With no thermistor connected, it should be full supply voltage, 3.3\_or 5\_volts depending on the controller.+Easiest way to do this is to disconnect the thermistor and measure voltage between both pins on the board. With no thermistor connected, it should be full supply voltage, 3.3\_or 5\_volts depending on the controller.
  
 ==== Check Thermistor Wiring ==== ==== Check Thermistor Wiring ====
  
-This measurement is simple, too. Disconnect the thermistor and measure resistance between both pins. At room temperature this should be around the nominal value of the thermistor, typically 10\_kOhms or 100\_kOhms. Warming the thermistor by hand should reduce this resistance.+This measurement is simple, too. Unplug the thermistor connector and measure resistance between both pins there. At room temperature this should be around the nominal value of the thermistor, typically 10\_kOhms or 100\_kOhms. Warming the thermistor by hand should reduce this resistance by a few kOhms.
  
 Measuring the thermistor while it's plugged in gives false results. Measuring the thermistor while it's plugged in gives false results.
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 This measurement can be done without the processor installed. If one is installed, the firmware shouldn't make these pins an output, but keep the default, input. This measurement can be done without the processor installed. If one is installed, the firmware shouldn't make these pins an output, but keep the default, input.
  
-Without a thermistor connected, both pins should read full 3.3\_volts (5\_volts on 5\_V controllers). Connecting a thermistor at room temperature should drop this not much, but a bit. Typically to 3.1\_... 3.2\_volts.+Without a thermistor connected, both pins should read full 3.3\_volts (5\_volts on 5\_V controllers). Connecting a thermistor at room temperature (not to these processor pins, but to the thermistor header on the board) should drop this not much, but a bit. Typically to 3.1\_... 3.2\_volts.
  
 Warming the thermistor by hand might change that slightly, perhaps by another 0.05\_V drop. Warming the thermistor with a lighter or soldering iron (be careful to not overheat it!), should drop that voltage further, down to very low readings, like 0.5\_V. Warming the thermistor by hand might change that slightly, perhaps by another 0.05\_V drop. Warming the thermistor with a lighter or soldering iron (be careful to not overheat it!), should drop that voltage further, down to very low readings, like 0.5\_V.
thermistor_troubleshooting.1460819890.txt.gz · Last modified: 2018/05/27 16:10 (external edit)