NO Voltage or HZ reading on meters

[dependable]

I would try replacing master switch before I went any further, as it is such an easy fix to try. Like any ignition type switch, it can develop a bad spot.

 

[Speddmon]

Replacing that master switch may be easy, but it's at least a $75 mistake if that is not the problem. Ask Doghead how much he paid for a USED one. I talked to the manufacturer about new ones..you don't want to know how much a new one would cost to have made.

 

[Rapracing]

I'm thinking it is probably not the switch. It has something to do with the field not staying charged. I can turn the switch to start and it flashes again and everything is okay until I let go of the switch. When the switch returns to the run position it should not be flashing. Correct??

That means the switch is doing its job I do believe??

I was just out and pulled the wires from the glow plugs (it started right after replacing them) since they are 24v as well. I didn't know if it could be related somehow but it did the same thing.

 

[n1oty]

Sounds like the AC voltage regulator is malfunctioning and not taking over.

John

 

[LuckyDog]

Check the diodes on the A4 board inside the distribution / control / reconnection box. (The access panel under the output lugs).

If you have voltage when flashing but not after releasing the switch that can be cause. As stated, when the VR dies (usually Q3) the voltage tends to go to high.

 

[Rapracing]

Check the diodes on the A4 board inside the distribution / control / reconnection box. (The access panel under the output lugs).

If you have voltage when flashing but not after releasing the switch that can be cause. As stated, when the VR dies (usually Q3) the voltage tends to go to high.

So I understand?? I just check on voltage on (either?) side of the diode when flashing? I assume that should be 24 volts?

 

[dependable]

I think he means check if the diodes are good. Should be very little resistance (OHMs) in one direction and a lot in the other. You can do this with generator not running.

 

[Triple Jim]

Very true, but many meters have difficulty measuring the resistance (ohms) of a diode. Some have a setting specifically to test diodes. A simple battery and test lamp can test them just as well, once one end is disconnected from the circuit.

 

[Rapracing]

Two more bits of information but first concerning the diodes. I believe they have to be taken out of the circuit to test? I don't have time to today to take the board out and test them but I did mess around for a few minutes earlier.


The First thing I found today: I am not sure why but my convenience plug has 90v on one side and 121v on the other.(that is while I hold it on start)

Secondly, I had stated previously that when I put the switch back to start it goes to 60hz and 220v. Upon further review what I found today is that it goes to 60hz and about 222v. I can turn it up to about 260 but when I turn it down the lowest it will go is the 222v. At about half way down on the knob I reach that is it goes no lower turning it clear down.

ETA: I am set on 120/240

 

[skidunits4you]

You should be checking voltage at load lugs,the convenience outlet picks up power from different windings and should not be used for any large load. check for voltage between L0 and L1 and L0 and L3 see if you get same readings or not. The main breaker will have to be on for this and remember lots of amps under that cover use care.you should get 120 volts between L0 and L1 and L0 and L3. L1 to L3 you should get 240 volts. I will have to agree VR should go high if bad. Is your throttle set so you are at 60 Hz?

 

[n1oty]

I respectfully disagree. Not all VR failures are of the higher than normal voltage variety. I think his next move should be to follow the test procedure on page 8-1 of the -34 manual. This test disconnects only the VR and substitutes a stable, nominal 12 volt DC source in its place. If he can start the generator and produce proper AC power with the battery substituting for the VR, this would confirm that the generator and the A4 diode matrix is GOOD. If the generator will not make power with the battery in place, then he must check the gen head and A4.

John

You should be checking voltage at load lugs,the convenience outlet picks up power from different windings and should not be used for any large load. check for voltage between L0 and L1 and L0 and L3 see if you get same readings or not. The main breaker will have to be on for this and remember lots of amps under that cover use care.you should get 120 volts between L0 and L1 and L0 and L3. L1 to L3 you should get 240 volts. I will have to agree VR should go high if bad. Is your throttle set so you are at 60 Hz?

 

[Isaac-1]

n1oty, I agree that the test procedures in the TM should be followed, but it is my understanding that the voltage regulators boards on the MEP-002a and MEP-003a work by suppressing the full output voltage from the saturatable reactor, so therefore are unlikely to be the culprit in this case, it however may be another part of the Voltage Regulation circuit. I also think there is a lot of confusion going on when throwing around terms like VR and AVR, as the voltage regulator circuit board is just one of a handful of components in the voltage regulation circuit.

Ike

 

[n1oty]

The VR circuit board actually has many individual circuits. The -12 and -34 plainly tell us that once the diesel engine comes up to speed and oil pressure is sufficient, releasing the start switch causes the VR to take control of the generator and control power production. This is where he has the problem. He may indeed have a problem away from the circuit board, even within the A4 diode matrix, but I'm not sure if he has the equipment to adequately test diodes. The test that I mentioned is so easy to perform and is the next step recommended in the -34 that I referenced earlier. The beauty of this test is that he only has to remove the two wires from that terminal block that connect the VR circuit board and connect a 12 volt battery in place of the VR wires, observing the polarity mentioned in the -34. Since this test only removes the VR circuit board from the equation, successful power generation means that the problem can ONLY reside on the VR circuit board. If that board is bad, it could any of the caps, resistors or transistors, although a Q3 failure generally means the generator will produce power at a higher than normal voltage.

John

n1oty, I agree that the test procedures in the TM should be followed, but it is my understanding that the voltage regulators boards on the MEP-002a and MEP-003a work by suppressing the full output voltage from the saturatable reactor, so therefore are unlikely to be the culprit in this case, it however may be another part of the Voltage Regulation circuit. I also think there is a lot of confusion going on when throwing around terms like VR and AVR, as the voltage regulator circuit board is just one of a handful of components in the voltage regulation circuit.

Ike

 

[Rapracing]

You should be checking voltage at load lugs,the convenience outlet picks up power from different windings and should not be used for any large load. check for voltage between L0 and L1 and L0 and L3 see if you get same readings or not. The main breaker will have to be on for this and remember lots of amps under that cover use care.you should get 120 volts between L0 and L1 and L0 and L3. L1 to L3 you should get 240 volts. I will have to agree VR should go high if bad. Is your throttle set so you are at 60 Hz?

Yes HZ is at 60. It adjusts up and down fine. The Voltage meter is at 222 and will adjust up from there but will go no lower no matter how far I turn the adjustment down. (That is while I hold the start button on start)

 

[n1oty]

I'm not sure why you are obsessing about an inability to turn the voltage lower than 222 or higher than 260. If anything, the TM states that the adjustment range should be somewhat narrower than that. I forget the exact range and I don't have the TM open at the moment, but I recall that it is something like 230 to 250, when the gen is set for 120/240 operation.

I suggest that you stay focused on the apparent loss of modulating voltage from the controls. We know from your prior posts that the field flash circuitry and the generator head itself is OK because holding the start position provides power. Power is lost in the transition from manual control to the automated functions of the voltage regulator circuit. It remains to be seen if that loss is occurring at the circuit board itself or some other component that comprises that circuit. The test called for in the -34 that I referenced earlier is the next logical test to be performed and effectively splits the circuit to show which side of the circuit has the problem. Hey, it could be something as simple as a loose connection at A4 or a loose connection at the VR board, but you won't know which half of the circuit is the problem until you do the test outlined in the -34.

John

 

[Speddmon]

I agree, you are set at 120/240, Even if you wanted to adjust the voltage down, 240 volts if where it should be. I know a lot of people like to say 110/220, but the proper and actual voltage you want to see is 120/240.

 

[dangier]

"Hey, it could be something as simple as a loose connection at A4 or a loose connection at the VR board, but you won't know which half of the circuit is the problem until you do the test outlined in the -34."

I had multiple electrical problems on my last 002a. Found a lot of connections loose and dirty (especially the voltage selector switch). In addition to the above tests, you might want to go through all electrical connections to make sure they are clean and tight. Takes a while, but might get you might be surprised on what you find. In doing that, also check the VR and A4 boards for burned components.

I know I echo some previous comments, but I wanted to reinforce the "clean and tight issue".
Saved me some money....

 

[dependable]

I would agree, the first 002 I got had some loose leads and one completely off the reconnection switch, including a couple of the main T connections.

 

[Rapracing]

I respectfully disagree. Not all VR failures are of the higher than normal voltage variety. I think his next move should be to follow the test procedure on page 8-1 of the -34 manual. This test disconnects only the VR and substitutes a stable, nominal 12 volt DC source in its place. If he can start the generator and produce proper AC power with the battery substituting for the VR, this would confirm that the generator and the A4 diode matrix is GOOD. If the generator will not make power with the battery in place, then he must check the gen head and A4.

John

I finally had a little time this evening to look at this test. I am confused at this point. Is there something that I am missing that would show me which wires I need to use for this test? Are the connections I remove on the terminal strip on the AVR board? Sorry, I don't mean to be stupid.

 

[n1oty]

Pull the cover from the side of the AC Reconnection box. The terminal block in question is literally just inside the box and probably the easiest area to work with. Locate position 5 and 6 on that terminal block. Disconnect the upper wire at 5 and 6. These go up to the VR circuit board. Wire up a 12 volt battery in their place, being careful to observe the correct polarity spelled out in the -34. I like to connect the wires first so I am sure not to short anything out. Once I have the wires attached to the terminal block, I then connect the battery, followed by starting the generator. If you do not get power generation then, your problem is below that level and probably somewhere within the AC Reconnection box. In that case, check the diode matrix at A4 carefully. If you do get power generation, your problem is one of the circuits on the VR circuit board, since that is the only part being bypassed for this test.

John