Multiquip MQP20P troubleshooting controller, Troubleshooting MEC20 Controller, Symptom, Solution

troubleshooting (controller)

CAUTION

Before opening the enclosure to perform troubleshooting or any service task, isolate the controller from any possible source of power. Failure to do so may result in serious personal injury or death due to electrical shock.

Troubleshooting (MEC20 Controller)

Symptom	Possible Problem	Solution
Does not power up even		Check wiring and repair. NOTE: The MEC 20 electronic
		fuse triggers when there is an overload condition and does
with correct DC power	Wiring errors or short circuit?
		not reset until the supply voltage is removed and overload
applied
		condition is corrected.
		Check that the "watchdog" LED on the rear of the PCB is
	Microprocessor defective?	flashing red meaning that the microprocessor is working. If
		not, repair or replace microprocessor.
LCD is not operational	Insufficient DC supply voltage?	Check voltage at input terminals B+ and B- (10-30 VDC).
		Adjust LCD contrast potentiometer (R115) on the rear of
	Bad LCD resolution?	PCB for good pixel resolution for the operating temperature
		of the unit.
	Controller not in OFF mode?	Check that the controller is set to the OFF mode before
Controller cannot be		resetting.
"reset"	Engine is running?	Check that the engine has come to a complete stop before
		resetting.
	Shutdown circuits reset?	Check that all shutdown circuits are reset (red shutdown
		LED must be off).
		Engine speed signal must be detected (speed signal green
No "RUN" output signal	No engine speed signal?	LED on) during cranking if the "run-output fail safe" feature
		is enabled. Verify correct magnetic pick-up signal at cranking
		(2.0 VAC min.)
		Check that the RUN output LED (on the rear of the PCB) is
	RUN output LED off?	on. If yes, verify relay contact operation on terminals #18 and
		#19.
Overspeed shutdown occurs		Verify that the controller has been programmed with the correct
	Controller not correctly programmed?	values for the number of flywheel teeth, nominal RPM, and
at normal speed		overspeed setpoint percentage.
		Verify that the controller has been programmed with the correct
	Controller not correctly programmed?	values for voltage sensing PT ratio and/or current sensing CT
		ratio.
	Battery not properly grounded?	Verify that the battery supply DC negative conductor is properly
		grounded to the engine block (i.e. to a common ground point.)
Voltage or current metering
		Verify that the controller's analog input has been properly
is reading incorrectly	Analog input not properly calibrated?
		calibrated.
		Verify that the voltage sensing wiring connection to the
	Incorrect wiring?	controller matches power distribution type (Note: standard
		direct voltage connection requires that the generator's neutral
		is solidly grounded).

page 38 —MQP20P STANDBY GENERATOR • operation and parts manual — rev. #1 (11/28/11)