Mep-802a - amp meter not working.

[Max Bladwin]

Hello,
Just recently purchased a mep-802a with 13 hours on it. I am having trouble with the amp meter. It does not move at all. I have checked the voltage at the batteries while it is running and the batteries are getting voltage from the alternator. I checked for voltage at the amp meter while the unit was running and did not read anything. Any help would be appreciated.

 

[Scoobyshep]

Check the selector switch position

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[Jeepadict]

My Amp meter is also misbehaving. When the set is on but not running the meter and fuel gauge are spot on. When the set is running both gauges bounce erratically in the general area of the actual reading. I suspect a loose shared ground connection...tho I haven't made the time to refrence the TM for troubleshooting just yet.

I vaguely recall something resembling a troubleshooting logic tree somewhere in the TM that may help you find your problem. Good luck!

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[Max Bladwin]

Pics are better then words. Check them out and let me know what you think.

 

[DieselAddict]

You need to move the AM/VM knob one more notch clockwise to read 120v single phase.

The fist thing to do if your readings are bouncy is to twist the AM/VM knob back and forth till your hand feels like its going to fall off then twist it about 5 more minutes. Soaking it with some good contact cleaner helps.

 

[Scoobyshep]

You need to move the AM/VM knob one more notch clockwise to read 120v single phase.

The fist thing to do if your readings are bouncy is to twist the AM/VM knob back and forth till your hand feels like its going to fall off then twist it about 5 more minutes. Soaking it with some good contact cleaner helps.

Little deoxit goes a long way

 

[Max Bladwin]

I am reading volts and % of load. It's this gauge.
The pic was taken with the generator running.

 

[kloppk]

None of the switches have any affect on the battery charge/discharge meter. That meter is connected directly across the MT4 shunt in the right front corner behind the meter panel.
MT4 is a shut (very low resistance resistor).
The voltage drop across it is measured by the charge/discharge meter.

In normal operation the meter will read slightly negative when priming the fuel system. After starting the engine the meter go up in the green positive region as the alternator is recharging the batteries. As the world batteries charge back up the gauge should sink back to near zero.

 

[Guyfang]

I am reading volts and % of load. It's this gauge.
The pic was taken with the generator running.

One of the reasons there is sometimes confusion, is because you do not use the correct name for what ever you are referring to. On the back of the control panel is a the proper "name", M4, that is called Battery Charging meter.

 

[Max Bladwin]

Ok. Thanks.
Well unlike fuel prices, M4 doesn't move at all.
I have watched some YouTube videos of others running there generators and they usually show a amp draw at startup and then about 5 amps charge after. Mine never moves. Is there a way to check it or is there a fuse that is blown somewhere?

 

[kloppk]

There is no fuse in that circuit. The two small wires on the front screws of MT4 go directly to M4. The wire numbers are 158A & 159A.
M4 is a voltmeter that measures the small DC voltage that develops across MT4 while the battery is discharging and charging.
After starting the genset the meter would normally go up to anywhere from 5 to 15 amps and drop back down.
You can test with a hand held meter to be sure MT4 is working.
When the battery is charging you should get these slight DC voltages across MT4 with a hand held meter.
0 Amps = 0.000 volts DC
5 Amps = 0.0125 volts DC (12.5 mV)
10 Amps = 0.025 volts DC (25 mV)
20 Amps = 0.050 volts DC (50mV)

If you get voltages at MT4 then repeat starting the set and measuring the DC voltage across the terminals on M4.
The voltages there should match what you read across MT4.

 

[Scoobyshep]

Easy check. Meter battery voltage when the engine is not running and again when its running. Voltage should be a but higher when running. That will verify the alternator is working

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[Guyfang]

Easy check. Meter battery voltage when the engine is not running and again when its running. Voltage should be a but higher when running. That will verify the alternator is working

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Scooby and I were thinking along the same wave length.

1. Simply push in CB1.
2. Put S1 in the run position.
3. Set the multi-meter up for D.C. voltage.
4. Measure at the two SMALL wires/terminals at MT4, (wire #159A and 158A). You should get 24 VDC or better.
5. If you get 24 VDC at MT4, go to M4, and measure at the two wires. You should get 24 VDC.
6. If you get 24 VDC at MT4, and not at M4, the meter is non-op. Get a new one.
7. Then do the same test when the set is running. If you get less the 24-25 volts, I would first check FU1, to see if its there, and if its good. If its there and good, and you do not get at least 24-25 VDC, your G2 is not operating.

 

[Rikjames92]

Correct me if im wrong but didnt they install something to be able to charge gel top batteries? I can check the TB later. An Inline fuse or something was installed during resets. I forget. Couldnt that prevent the gauge from working properly?

 

[nextalcupfan]

Correct me if im wrong but didnt they install something to be able to charge gel top batteries? I can check the TB later. An Inline fuse or something was installed during resets. I forget. Couldnt that prevent the gauge from working properly?

I don't believe you need anything special to charge gel batteries. (I'd like to also mention the Optima Red Tops the military uses are NOT Gel)

The only fuse I know of is the Quad Fuse Mod. Which would have nothing to do with the battery charging system.

 

[Guyfang]

I don't believe you need anything special to charge gel batteries. (I'd like to also mention the Optima Red Tops the military uses are NOT Gel)

The only fuse I know of is the Quad Fuse Mod. Which would have nothing to do with the battery charging system.

Actually, there is FU1. Battery charging fuse.

 

[Guyfang]

Correct me if im wrong but didnt they install something to be able to charge gel top batteries? I can check the TB later. An Inline fuse or something was installed during resets. I forget. Couldnt that prevent the gauge from working properly?

Perhaps you need to look at the TM. Everything you need to know is in the TM. No, not the Quad fuse. But there is a TB that covers that.

 

[Rikjames92]

Perhaps you need to look at the TM. Everything you need to know is in the TM. No, not the Quad fuse. But there is a TB that covers that.

Sorry for the garbage picture

 

[Rikjames92]

Basically i was thinking of a different model

 

[Max Bladwin]

1st thanks for all the reply's. I would have responded with the my findings sooner had it not been for an episode of the old Covid-19. I am better now and put a multimeter on it and checked the voltages at MT4. There is voltage so I am confidant that the meter is bad. It looks to me like there is brown corrosion inside. I would guess there is no way to rebuild because they are sealed. Any suggestions on where I can get a new one? I didn't see any on ebay.

So 2nd question. I will open a new thread if people think it applies. When I started feeling up to looking into the issue with the Meter M4, my Temp meter M6 starting acting up. Start the gen and it would sit at lowest setting then maybe the dial would come alive and settle on a temp (around 180). The temp meter stopped reading all together. I purchased a new one off ebay and installed it. At 1st the temp would settle out at 200 degrees. Just today I noticed that the temp now settles at 218ish. I checked the meter and it has a burnt electronic smell definitely coming it. I am thinking it is going to need to be replaced again. I should also mention the gen does not act or feel like it is overheating. So is there a way to measure if the meter is actually accurate? Aside from ebay any recommendations for a place to buy one of these?