MEP-003a No voltage

[jamawieb]

Starter interrupter switch is now working properly. When engine speed comes up, the push rod moves the interrupter switch so the starter doesn't engage while holding the start switch. No voltage at the output lugs, no voltage or frequency on the gauges, no voltage at the convenience outlet.



Is my next test to follow procedure 8-2 in the -34 manual? "Disconnect the voltage regulator at the exciter wires (wires P67C16 at TB3-5 and P60E16 at TB3-6). Connect a 12 volt battery in place of the regulator with the (+) terminal to TB3-6 and (-) terminal to TB3-5. Run the engine with the battery in place of the voltage regulator. If there is output now, the voltage regulator is bad. If there is no output, the main alternator is bad."

Yes I believe the test you're describing is direct current to the exciter board, which should result in voltage generation. In -34 there is a test setup for the output box which test CVT1, Linear Reactor, A4 (exciter board), etc. It gives resistance values for everything. Most of the time I find it to be CVT1 transformer has shorted out. 1 time I found the Linear Rector Shorted which cause no-output. 1 time it was because of A1 relay assembly in the gauge cluster which had an open diode that caused the R1 resistor on the A4 exciter board to fry.

 

[juddspaintballs]

Start the gen set up. While you do that, have someone use a multi meter to check the input side of the frequency transducer, for 120 VAC. At the beginning of you thread, you spoke of a reading on your hertz meter. If the hertz meter gives you a reading, it's getting 120 VAC. So let's confirm what's happening here. There is a world of difference between no AV output and not getting output on the load terminals.

I clipped my Fluke to the + terminal of the transducer and the negative lead to the ground main ground lug at the output lugs. While starting, after it ran, and while holding S1 in the start position--all three conditions I had no AC voltage reading on the Fluke meter.

Yes I believe the test you're describing is direct current to the exciter board, which should result in voltage generation. In -34 there is a test setup for the output box which test CVT1, Linear Reactor, A4 (exciter board), etc. It gives resistance values for everything. Most of the time I find it to be CVT1 transformer has shorted out. 1 time I found the Linear Rector Shorted which cause no-output. 1 time it was because of A1 relay assembly in the gauge cluster which had an open diode that caused the R1 resistor on the A4 exciter board to fry.

I ran the test that I quoted above (Procedure 8-2). I disconnected the appropriate two wires at TB3-5 and TB3-6 and hooked up a motorcycle battery in the correct orientation to TB3. With the motor running, I had 120v at L1, L2, and the convenience outlet. The voltmeter on the generator was just a tick over 240v and couldn't be adjusted, which I know is a function of the battery being wired in to TB3. The Hz meter was pegged to the far right (above 65 Hz), but I think that might be a condition of the battery being wired in place at TB3 as well. The Fluke read ~60Hz at the convenience outlet with minor (fewer than 1/10th of a Hertz) fluctuation.

This points to a bad voltage regulator, correct?





Now for a little surprise. When I took the cover off to find TB3, I discovered that mice had made that box a nice little nest.




I cleaned it out and inspected all of the wiring as best I could. I only found one wire it looks like they chewed at and they only took the insulation off of it and it's not touching anything. I'll wrap it back up with regular electrical tape.





So my thought was maybe there was a damaged wire I couldn't see, and that's why the battery at TB3-5 and TB3-6 wired in suddenly made things work. I tested continuity in the two wires (P67C16 and P60E16) back to the A2-12 and A2-18 and found them continuous. Beyond that, I don't know where else to look. The mouse nest could simply be a nasty little surprise and not the actual cause of my problem.


Thoughts? Bad VR or should I check something else out first?



Thank you for the patience. I've been busy with work and doing stuff around the house. I'm learning terminology, where to find some of these things I'm reading about (TB3 took me a while), and how to check things out. I'd like to get this thing functional again and then consider the possibility of using the GMG auto-start kit so I can hardwire it to the house as a backup generator.

 

[juddspaintballs]

Yes I believe the test you're describing is direct current to the exciter board, which should result in voltage generation. In -34 there is a test setup for the output box which test CVT1, Linear Reactor, A4 (exciter board), etc. It gives resistance values for everything. Most of the time I find it to be CVT1 transformer has shorted out. 1 time I found the Linear Rector Shorted which cause no-output. 1 time it was because of A1 relay assembly in the gauge cluster which had an open diode that caused the R1 resistor on the A4 exciter board to fry.

I'm still working on figuring out what everything is. I've tested the CVT1 per the manual. I get readings of 2.0 ohms across H3/H4 and H5/H6. I suspect some error in the meter as those aren't very far off of the allowable variances. Is that a problem if it's accurate? When they go bad, are they way off? The other resistances on the other terminals to test were all in spec.

I'm still figuring out how to test the linear reactor and A4 assembly. I've found what I need in the manual and I found where they are, I just haven't taken things apart yet and checked.

 

[juddspaintballs]

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[Guyfang]

I clipped my Fluke to the + terminal of the transducer and the negative lead to the ground main ground lug at the output lugs. While starting, after it ran, and while holding S1 in the start position--all three conditions I had no AC voltage reading on the Fluke meter.

Even if you had a good gen set, measuring there would not have given you 120 VAC.

A3 Terminal 1 Wire number H9H16
A3 Terminal 2 Wire number X12H16
A3 Terminal + Wire number D75A1
A3 Terminal - Wire number D74A16

Terminal 1&2 are AC voltage
Terminal +&- are DC voltage.

I should have broken it down like this to begin with.
Another helpful hint is to use the schematics from the -34 manual, as they are the cleanest and easiest to read, if you are using the -12 schematics.

I am not sure your VR is bad. The S1 start switch is what excites the Main AC. The Volt Reg takes over after that, when it senses that the main gen has been excited, and producing 120 volts. You excited the gen set with you motorcycle battery. That means the main gen is good. But when you start the gen set with the S1, and no motorcycle battery, the main gen produces no voltage. Why? Did the hertz meter move at all when you mistakenly measured at the + and ground?

 

[juddspaintballs]

Guyfang, I'm going outside right after I post this to test that again. Thank you for clarifying. I am using both the -34 and -12 manuals and I'm also heavily using the schematic on top of the control box since mine is in good shape. I assume I should get 120v at Terminal 1 and 2 when using the L0 lug as my ground or should I get 120v between Terminal 1 and Terminal 2 at A3? I'll test both ways and find out.



Referring back to what jamawieb posted about testing the linear reactor and A4 board:

All six diodes on the A4 tested correctly per the manual.

The Linear Reactor was weird. Between terminals 3 and 4 and also between terminals 5 and 6 I had proper resistance. Between terminals 1 and 2, it started as low as 9 ohms and was steadily rising until I took my leads off around 16 ohms. All connectors on the outside of the output box were disconnected as the manual states to do and there was no battery or anything extra connected to it. Is this a bad linear reactor?

 

[juddspaintballs]

I clipped my Fluke to the + terminal of the transducer and the negative lead to the ground main ground lug at the output lugs. While starting, after it ran, and while holding S1 in the start position--all three conditions I had no AC voltage reading on the Fluke meter.

Even if you had a good gen set, measuring there would not have given you 120 VAC.

A3 Terminal 1 Wire number H9H16
A3 Terminal 2 Wire number X12H16
A3 Terminal + Wire number D75A1
A3 Terminal - Wire number D74A16

Terminal 1&2 are AC voltage
Terminal +&- are DC voltage.

I should have broken it down like this to begin with.
Another helpful hint is to use the schematics from the -34 manual, as they are the cleanest and easiest to read, if you are using the -12 schematics.

I am not sure your VR is bad. The S1 start switch is what excites the Main AC. The Volt Reg takes over after that, when it senses that the main gen has been excited, and producing 120 volts. You excited the gen set with you motorcycle battery. That means the main gen is good. But when you start the gen set with the S1, and no motorcycle battery, the main gen produces no voltage. Why? Did the hertz meter move at all when you mistakenly measured at the + and ground?

Between A3 Terminal 1 and Terminal 2, I had 0.475v AC, which is what I was reading at the output lugs L1 and L2 in the very first post. This was with the generator running and there was no change whether I was flashing or letting it run without holding the start switch.


Between + and 1 on the frequency transducer, I had no DC voltage reading. This was with the generator running and there was no change whether I was flashing or letting it run without holding the start switch. Also no DC voltage reading with the generator not running.


When I first start the generator, the frequency meter moves from far left to far right and then back to far left very much like a gauge sweep. It doesn't stay at any value. It just sweeps over and then back to pegged far left like it's not getting any reading. It doesn't change when I flash the field.

 

[jamawieb]

I'm still working on figuring out what everything is. I've tested the CVT1 per the manual. I get readings of 2.0 ohms across H3/H4 and H5/H6. I suspect some error in the meter as those aren't very far off of the allowable variances. Is that a problem if it's accurate? When they go bad, are they way off? The other resistances on the other terminals to test were all in spec.


I'm still figuring out how to test the linear reactor and A4 assembly. I've found what I need in the manual and I found where they are, I just haven't taken things apart yet and checked.

Usually when they go bad and cause your issue, you won't have a reading because the coil has shorted so I suspect its okay.
​

 

[jamawieb]

Guyfang, I'm going outside right after I post this to test that again. Thank you for clarifying. I am using both the -34 and -12 manuals and I'm also heavily using the schematic on top of the control box since mine is in good shape. I assume I should get 120v at Terminal 1 and 2 when using the L0 lug as my ground or should I get 120v between Terminal 1 and Terminal 2 at A3? I'll test both ways and find out.



Referring back to what jamawieb posted about testing the linear reactor and A4 board:

All six diodes on the A4 tested correctly per the manual.

The Linear Reactor was weird. Between terminals 3 and 4 and also between terminals 5 and 6 I had proper resistance. Between terminals 1 and 2, it started as low as 9 ohms and was steadily rising until I took my leads off around 16 ohms. All connectors on the outside of the output box were disconnected as the manual states to do and there was no battery or anything extra connected to it. Is this a bad linear reactor?

On A4 did you test the 56 ohm resistor?
I think you may have found the problem in the linear reactor. ​

 

[juddspaintballs]

I tested CR-1, CR-2, CR-3, CR-4, CR-5, CR-6. I completely missed testing the 56 ohm resistor. I can do that tomorrow.

Where would I find a linear reactor?

 

[juddspaintballs]

Just kicking things around in my head here, but with a positive test using the battery on TB3-5 and TB3-6, wouldn't that mean that the problem has to be in the control box (AC Voltage Regulator area) and not in the AC output box? Doesn't removing those two wires simply take the AC VR out of the equation and replace it with a battery? The TM says if the test results in voltage then the AC VR is bad. I'm willing to believe it is something else that is bad, but could someone explain why it isn't definitively the VR after that test?

 

[jamawieb]

They have a linear reactor on ebay for $69 I think.

 

[jamawieb]

Just kicking things around in my head here, but with a positive test using the battery on TB3-5 and TB3-6, wouldn't that mean that the problem has to be in the control box (AC Voltage Regulator area) and not in the AC output box? Doesn't removing those two wires simply take the AC VR out of the equation and replace it with a battery? The TM says if the test results in voltage then the AC VR is bad. I'm willing to believe it is something else that is bad, but could someone explain why it isn't definitively the VR after that test?

That's what the TM says but its not true. Your test does take the VR out and you hooked directly into the exciter board. The VR takes readings from CVT1 and the linear reactor to determine how to regulate the voltage. So if those are not working, the voltage regulator will not work. I've only had 1 experience where it was the actual VR when I had no voltage. The cause was CVT1 99% of the time, 1 time it was the linear reactor. It took me almost 2 months to find it to be the linear reactor because several people told me it couldn't be it because it doesn't have an effect on voltage but it tested bad and after replacement everything worked perfect.

 

[jamawieb]

It could be the VR not saying it is not. I think we are trying to help you from spending unneeded money on a VR, when it may not be the problem. We have all been there and spent good money a VR, only to find out it wasn't the problem. But if it is the VR I would highly recommend upgrading to TripleJims VR [FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]http://www.lakeserv.net/mep/index.html
I have a couple of these on standby just in case.
[/FONT]

 

[juddspaintballs]

I'm going outside in a few minutes to check out that resistor that I forgot to check yesterday. I'm going to double check the linear reactor while I'm in there.



And I fully do intend on getting his VR board at some point. I wouldn't be sad if I had to buy it now.

 

[juddspaintballs]

I checked the resistor on the A4 board. It reads 55.8 ohms. I'd call that 56 ohms. I'm pretty sure that means the A4 checks out all around.


I re-checked the linear reactor. Between terminals 3/4 and 5/6 I had 12.8 and 12.9 ohms, which is in spec of 13.5 ohms +/- 1.35 ohms. Between terminals 1/2 I had the same weird creeping reading that started off as low as about 6 ohms today and crept up in 0.02 ohm increments about every second until I got tired of holding the leads when it was up to about 16 ohms again.

 

[Guyfang]

Did you compleatly disconnect the L/R before testing it?

 

[juddspaintballs]

The manual said to disconnect the electrical connectors on the ac output box or something like that. I'm not home to reread the manual, but it made it sound like just unplug the 4 exterior connectors on the box. I tried to undo the 6 connections on the linear reactor but the wiring is so tight in there that it's nearly impossible without removing something else too.

 

[Guyfang]

When I get home will read the procedure.

 

[juddspaintballs]

"(5) Linear Reactor (Ll). Disconnect electrical connectors from control box. Use an ohmmeter to check resistance of each of the three windings in the reactor by checking resistance between terminals 1 and 2, 3 and 4, 5 and 6. Resistance for each winding must be 13.5 ohms plus or minus 1.35, if not replace reactor."


It doesn't seem very clear, but to me it sounds like I just disconnect those four connectors and test.