Table 5‐2 Troubleshooting Guide (Digital Controller Only)
Problem | Possible Cause | Remedy |
Controller does not power up even with | Wiring Mistake | Check that there are no wiring errors/short circuits connected to the |
correct DC power applied |
| controller. |
| Overload Condition | The MEC 20 contains an electronic fuse that trips when an overload |
|
| condition exists and does not reset until the supply voltage is |
|
| removed and reapplied after the overload condition is corrected. |
LCD Display cannot be viewed | Microprocessor failure | Check that the controller's microprocessor is running by observing a |
|
| red flashing “watchdog” LED on the rear of the PCB. Replace |
|
| controller if failed. |
| Improper Supply Voltage | Check DC supply voltage at terminals B+ & B- |
| Improper contrast adjustment | Adjust LCD contrast potentiometer (R115) on rear of PCB for best |
|
| display. |
Controller cannot be “Reset” | Engine not stopped | Verify the engine is at a complete stop before trying to reset. |
| Controller not in OFF mode | Set the controller to the OFF mode before trying to reset. |
|
|
|
No “RUN” output signal | “Shutdown Faults” not reset | All shutdown faults must be reset (red shutdown LED must be off). |
| Engine speed not detected at cranking | Engine speed signal must be detected (speed signal green LED on) |
|
| during cranking if the |
|
| correct magnetic pickup signal at cranking (2.0VAC min. during |
|
| cranking). |
Run Contact not closing (terminals #18 & #19)
Check that the RUN output LED (on the rear of the PCB) is on. If yes, verify relay contact operation on terminals #18 & #19. Replace controller if failed.
Overspeed shutdown occurs at normal speed
Controller programmed values are wrong or controller has failed.
Verify the controller programmed values are correct for the number of flywheel teeth, nominal RPM, and overspeed setpoint percentage. Replace controller if failed.
Voltage or current metering is incorrect | Controller programmed values are wrong | Verify the controller programmed values are correct for the voltage | |
|
| sensing PT ratio and/or current sensing CT ratio. | |
| Ground is missing | Verify that the battery supply DC negative conductor is properly | |
|
| grounded to the engine block (i.e. to a common ground point). | |
| Analog input needs to be calibrated | Verify that the controller's analog input is properly calibrated. | |
| Voltage sensing wiring mistake | Verify the voltage sensing wiring connection to the MEC 20 matches | |
|
| power distribution type. | |
|
| Note: standard direct voltage connection requires that the | |
|
| generators neutral is solidly grounded. | |
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|
| |
Engine temperature or oil pressure | Analog input needs to be calibrated | Verify that the controller's analog input is properly calibrated. | |
display is incorrect | Failed engine sensor | Verify engine sensors. | |
|
| Note: engine sensors must be factory supplied units only. | |
| Ground is missing | Verify that the battery supply DC negative conductor is properly | |
|
| grounded to the engine block (i.e. to a common ground point). | |
|
|
| |
Engine temperature or oil pressure | Sending unit is disconnected (open | Verify the sending units wiring to controller terminals #37 & #38 (i.e. | |
displays 9999 | circuit) | wiring is not open or shorted). | |
OR | Defective sending unit | Verify the engine mounted senders have correct resistance values | |
Engine alarms are ON for high engine |
| for corresponding input temperature or pressure. | |
temperature or low oil pressure when | Wrong Temp or pressure calibration | Verify calibration. | |
engine is operating properly | |||
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| ||
Keypad Buttons (switches) do not | Keypad not connected to controller | Verify the interconnecting ribbon cable between the lexan faceplate | |
operate. |
| and main printed circuit board is correctly connected. | |
|
| Replace controller if failed. |
MN2408 | Troubleshooting and Maintenance 5‐3 |