Diagnostics and Troubleshooting
346 809480 Instruction Manual XPR300
Table 3 9 – Minimum and maximum ohmic resistance values for thermistors
At approximately 25ºC (77ºF), you can expect a resistance of
approximately 10,000 ohms.
3. If the resistance is above the maximum value, contact your cutting machine supplier or regional
Hypertherm Technical Service team. They can help you to decide if there is a wiring fault or if
thermistor replacement is necessary.
4. If the resistance is at or near 0 ohms:
a. Inspect the wiring between each thermistor and its connector pins.
b. Look for shorts between wires or to the ground.
5. If the resistance is within range, continue cutting system operation.
6. If the resistance remains below the minimum ohmic value or does not change after you allow the
coolant to reach 85ºC (185ºF) or below, contact your cutting machine supplier or Hypertherm
Technical Service team.
7. If the thermistor resistance is within range when the thermistor is disconnected from the control
PCB and the code continues when the thermistor is reconnected to the control PCB, contact
your cutting machine supplier or regional Hypertherm Technical Service team. They can help you
decide if control PCB replacement is necessary. Refer to Plasma power supply control PCB
(141322) on page 351.
8. If the code continues, or if you cannot find or resolve the problem with these corrective actions,
contact your cutting machine supplier or regional Hypertherm Technical Service team.
Thermistor temperature Minimum resistance (Ohms) Maximum resistance (Ohms)
25ºC (77ºF) 9,000 11,000
35ºC (95ºF) 5,000 7,000
45ºC (113ºF) 3,900 4,900
55ºC (131ºF) 2,500 3,500
65ºC (149ºF) 1,500 2,500
75ºC (167ºF) 1,000 2,000
85ºC (185ºF) 750 1,250
95ºC (203ºF) 600 1,000
105ºC (221ºF) 400 800
115ºC (239ºF) 300 600
125ºC (257ºF) 200 500
135ºC (275ºF) 150 400
145ºC (293ºF) 150 250
155ºC (311ºF) 125 225
165ºC (329ºF) 100 175
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