THOMSON MEC 20 - V1.82

Questions and Answers

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becky17Aug 16, 2025
Why is the voltage or current metering reading incorrectly on my THOMSON MEC 20 - V1.82 Controller?
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  Michelle NicholsonAug 16, 2025
  If the THOMSON Controller's voltage or current metering is reading incorrectly, ensure the controller is programmed with the correct values for the voltage sensing PT ratio and/or current sensing CT ratio. Also, check that the battery supply DC negative conductor is properly grounded to the engine block. Verify the controller’s analog input has been properly calibrated and the voltage sensing wiring connection to the MEC 20 matches power distribution type. Note that standard direct voltage connection requires that the generators neutral is solidly grounded.
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aperezAug 18, 2025
What to do if the engine temperature or oil pressure display on my THOMSON MEC 20 - V1.82 is reading incorrectly?
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  George WagnerAug 19, 2025
  If the THOMSON Controller's engine temperature or oil pressure display is reading incorrectly, verify that the controller’s analog input has been properly calibrated as per manual instructions. Also, check that the engine sensor wiring is correct, noting that engine sensors must be factory supplied units only. Ensure that the battery supply DC negative conductor is properly grounded to the engine block.
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Teresa VargasAug 22, 2025
Why does overspeed shutdown occur at normal speed on my THOMSON Controller?
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  nsmithAug 22, 2025
  If your THOMSON Controller experiences an overspeed shutdown at normal speed, verify that the controller has been programmed with the correct values for the number of flywheel teeth, nominal RPM, and overspeed setpoint percentage.
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Sheila PhillipsAug 25, 2025
Why does the engine temperature or oil pressure on my THOMSON MEC 20 - V1.82 Controller display 9999?
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  Lisa GoodmanAug 26, 2025
  If the engine temperature or oil pressure displays 9999 on your THOMSON Controller, check the wiring from the MEC 20 terminal #37 & #38 to the engine mounted sender to ensure it is correct (i.e., wiring is not open or shorted). Verify the engine mounted senders have correct resistance reading for corresponding input temperature or pressure (refer to the Analog Temperature and Pressure Calibration table for values). Verify calibration.
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Steve WrightAug 27, 2025
Why does my THOMSON MEC 20 - V1.82 show engine alarms on high engine temperature or low oil pressure when the engine is operating normally?
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  Jacob HaleAug 28, 2025
  If your THOMSON Controller shows engine alarms on high engine temperature or low oil pressure when the engine is operating within normal limits, check the wiring from the MEC 20 terminals #37 & #38 to the engine mounted senders to ensure it is correct (i.e., wiring is not open or shorted). Verify that the engine mounted senders have the correct resistance reading for the corresponding input temperature or pressure (refer to the Analog Temperature and Pressure Calibration table for values).
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Edward RussoAug 31, 2025
How to troubleshoot no “RUN” output signal on THOMSON MEC 20 - V1.82 Controller?
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  Beth SmithAug 31, 2025
  If you are not getting a “RUN” output signal from your THOMSON Controller, check that all shutdown circuits are reset (the red shutdown LED must be off). If the “run-output fail safe” feature is enabled, the engine speed signal must be detected (speed signal green LED on) during cranking; verify correct magnetic pick-up signal at cranking (2.0VAC min.). Check that the RUN output LED (on the rear of the PCB) is on. If it is, verify relay contact operation on terminals #18 & #19.
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Michelle CruzSep 2, 2025
What to do if the LCD Display is not operational on my THOMSON MEC 20 - V1.82?
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  Melissa JonesSep 3, 2025
  If the LCD Display is not operational on your THOMSON Controller, check that the controller’s microprocessor is running by observing a red flashing “watchdog” LED on the rear of the PCB. Also, check that there is sufficient DC supply voltage to input terminals B+ & B- (10-30VDC). Verify that the LCD contrast potentiometer (R115) on rear of PCB is adjusted for good pixel resolution for the operating temperature of the unit.
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Jesse TorresSep 6, 2025
How to troubleshoot THOMSON MEC 20 - V1.82 Controller that does not power up?
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  Nicole ThomasSep 6, 2025
  If the THOMSON Controller does not power up even with correct DC power applied, check that there are no wiring errors or short circuits connected to the controller. Note: The MEC 20 contains an electronic fuse that triggers upon an overload condition and does not reset until the supply voltage is removed, and the overload condition is corrected.
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Elizabeth BryantSep 9, 2025
Why key presses on the lexan faceplate of my THOMSON MEC 20 - V1.82 do not operate?
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  Gary ByrdSep 9, 2025
  If the keys on the lexan faceplate of your THOMSON Controller do not operate, verify that the interconnecting ribbon cable between the lexan faceplate and the main printed circuit board is correctly connected.
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Linda Lewis DDSSep 12, 2025
What to do if my THOMSON MEC 20 - V1.82 cannot be reset?
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  William LunaSep 12, 2025
  To reset the THOMSON Controller, first check that the controller is set to the OFF mode before trying to reset it. Also, ensure that the engine has come to a complete stop before attempting to reset.