Panasonic DX-2000 Service Manual page 206

Note:
If an 021 series Error Code occurs, 021-25 (Thermistor Open) or 021-26 (Thermistor detected temperarure over 200 °C),
a pre-programmed recovery safety software is activated to protect the unit and the service personnel during abnormal
increase in temperature.
Once activated, this information is downloaded into the LPC PC Board's SRAM, disabling the Fuser Lamp and preventing
it from turning ON again.
In order to reset this circuit, please follow the procedure below.
1) Reset the LBP Fuser by using Test Mode 7-1-2 (Section 5.6) and Power OFF/ON.
2) Replace the Thermistor or Fuser Unit. If the problem persists.
3) Replace the LPC PCB.
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