MEP-802A strange behavior

[flainn]

Hi,

I've looked through the TM's troubleshooting procedures but can't find anything that addresses the random behavior I'm seeing with my MEP-802A.

Since I got it, sometimes it acts completely normal. The control panel has power, it starts right up and runs just fine. I have load tested it with about 4 KW and it generates power just fine, does not overheat, has plenty of fuel. Batteries are on a 24-volt tender all the time and are new.

But at other times, the control panel has no power at all. Or, I can get the engine to start and it will randomly shut itself off with no fault indicator, and then when I try to restart the control panel will have no power. Then if I leave it alone for a few days or weeks, it will be back to normal after just sitting.

I'd like to get it to the point where I can count on it to work when needed, but right now it's pretty flaky. Is there something I should check? The behavior just doesn't make any sense to me.

 

[Scoobyshep]

Sounds like a bad connection somewhere (or bad contact) if its killing all the controls id look at the dc breaker estop and the common points of the stop run switch.

Sent from my SM-G973U using Tapatalk

 

[Guyfang]

Think about this. Check the canon plugs on the bottom of the control panel. remove them, look into both parts, with a flashlight. Make sure nothing is burnt. If the plug is not inserted correctly, you can get this problem. Also if the pins are short out/burnt off. If that's good to go, next look at the S17. Make sure its all the way pulled out.

If it looks and tests good. Do this. Start and stop it, until you have the fault. Then Measure from ground to MT4, (Battery Charging Ammeter Shunt) terminal #4, (right side big wire) for 24 VDC. Got no volts? Then check that wire, back through the C- plug to the starter. Got VDC at MT4-4? Then measure from MT4-1, (left side big wire on MT4) to ground. Got volts? Then measure at S10-2, (Dead crank switch) to ground. Got volts? If not, the problem is CR1. I find that hard to believe, because a diode works or it doesn't. But check anyway. If you have VDC at the S10-2, then and the S10 is in the normal position, you should have VDC at S10-3. No volts, S10 is bad. Got volts.? Measure at S17. Both sides should have VDC, to ground, if the S17 is pulled out. Only one side hot? Then S17 is bad. Both sides hot to ground? Then go to CB1 and see if both sides are hot to ground, with the CB pushed in. If its pushed in, and only one side is hot to ground, CB1 is bad.

 

[flainn]

Thank you both for the suggestions -- I will work my way through this over the next few days and let you know what I find.

 

[Scoobyshep]

Good luck. Intermittent problems are a pain in the ass

Sent from my SM-G973U using Tapatalk

 

[flainn]

I worked my way carefully through all of guyfang's steps, and none of the components mentioned tested as bad. Everything seems to be normal, except I can't get the start switch to do anything (no preheat click, no fuel pump noises, no crank). Dead crank works fine.

I'm wondering at this point whether it's the start switch itself that has gone bad. Is there a test procedure for it?

 

[kloppk]

On the start switch there should be 24 volts DC on terminals 2,4,6,8 as long as the Dead Crank is in the NORMAL position, the Emergency OFF button is pulled out and breaker CB1 is not tripped.
You can start by checking for 24 volts DC power to those terminals on S1.

 

[Guyfang]

When checking for 24 VDC on S1, the voltage comes in on S1-8. There is a bridge between S1-8, 6, 4, 2. So if you have it on S1-8, and not on another, it could be a loose screw. Depends on what type S1 you have. If is the MK1 style, the "bridge" is several removable links. They sometimes get loose, and even fall out. Take a picture of your S1 if you do not know the difference between the THREE styles of S1.

And yes, there is a test procedure for S1. Its in the TM.