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MEP 002a Not producing Electricity, I am looking for someone who is familiar with the 002a to work on it.
- Thread starter chb32nj
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Rick, We might have a couple of rats in NJ!! Lol!We have no rats in NJ, well as long as you don't consider the government.
One thing we do have an abundance of is chipmunks and they will go up the exhaust and actually store food past the open valves on top of pistons.
Just want to give everyone a quick update. I found a Generator Tech from a local repair business that is very familiar with the Onan DJ series and rotating diodes. He will be stopping by in a week or 2 and take a look at it. I will keep everyone informed when he stops by and hopefully make some progress.
I want to thank everyone for all the help and suggestions! I greatly appreciate it!
I have an update on my 002a not producing power. First I want to thank everyone here for all the help you have given to me!
And a big shout out and thank you to Ray70 for rebuilding the IP on my MEP002a Gen #2. Runs Perfect now!
The Gen Tech that was going to stop by and check the diodes never showed up.
After reading the TM and a couple of threads I checked the diodes myself. I unbolted them 1 at a time and checked the resistance with my multi meter, which to my surprise had a diode test function. Every one tested ok, I think! Nothing one way and when I reversed it showed resistance. I am attaching pictures in case I am not stating what I did correctly. 3 pictures are from F1 and 3 are from F2. Not sure what to do next.
And a big shout out and thank you to Ray70 for rebuilding the IP on my MEP002a Gen #2. Runs Perfect now!
The Gen Tech that was going to stop by and check the diodes never showed up.
After reading the TM and a couple of threads I checked the diodes myself. I unbolted them 1 at a time and checked the resistance with my multi meter, which to my surprise had a diode test function. Every one tested ok, I think! Nothing one way and when I reversed it showed resistance. I am attaching pictures in case I am not stating what I did correctly. 3 pictures are from F1 and 3 are from F2. Not sure what to do next.
Attachments
To add a little bit more info to Chris' post above, while he was here in RI we swapped out both the control cube and AC reconnection box with no change. This is also what led us to both feel that the previous post about the rotating diodes being the problem were most likely correct. At this point I would still say the problem is most likely somewhere within the generator head itself.
Best thing I can suggest is a close inspection of the wiring going to the generator, paying closest attention to the plug with the 2 small wires. I know the wiring on that machine looked good, but pay close attention to things like corrosion or damaged pin sockets in the mating plugs.
Also, see what can be seen within the gen head itself as far as wiring connections to be sure everything is good. Also follow the instruction in the TM to check the winding resistances of the generator, this resistance test would definitely help highlight any internal shorts or opens in the windings.
Best thing I can suggest is a close inspection of the wiring going to the generator, paying closest attention to the plug with the 2 small wires. I know the wiring on that machine looked good, but pay close attention to things like corrosion or damaged pin sockets in the mating plugs.
Also, see what can be seen within the gen head itself as far as wiring connections to be sure everything is good. Also follow the instruction in the TM to check the winding resistances of the generator, this resistance test would definitely help highlight any internal shorts or opens in the windings.
The small connector going to the main gen should be J12? Pins A&B are the F1 and F2 wires, that provide the initial excitation. Pin A is P67B and Pin B is P60G. Take the plug off, and Test at the two pins while someone else tries to start the gen set. Even after it starts, hold up the S1. you should get 24 VDC, I think. If you get no DC voltage, the main gen can not light off.
I was able to check the winding resistance on the generator today. Nothing good to report. I did not get 1 good reading. Everything was either 0 or open circuit. I thought at least one circuit would have some resistance. I am attaching a chart of the circuits tested and the results. I think I should just look for a different Generator head and change it out. Thanks again to everyone for all your help! Very much appreciated!
1/10/2021-This is an edit to make a correction to the chart. See post #74 for an updated chart. Here is the correction; Test #5 is T2 & T5 which is P9D and P10F. When I wrote down all the crossovers from wire to plug position I made a mistake for T5 and listed it as P9F instead of P10F. Sorry for any confusion.
1/10/2021-This is an edit to make a correction to the chart. See post #74 for an updated chart. Here is the correction; Test #5 is T2 & T5 which is P9D and P10F. When I wrote down all the crossovers from wire to plug position I made a mistake for T5 and listed it as P9F instead of P10F. Sorry for any confusion.
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If those readings are correct your gen head is a gonner. I can see getting readings that are maybe an ohm off, simply due to differences in meters and resistance in your leads, but all open and shorted circuits would seem to indicate catastrophic damage.
Maybe I'm reading the numbers wrong, but reading #15 P10-A looks like a direct short, doesn't it?
The manual says all readings of P9 and P10 to A-F should all be high. A low resistance on any of them should be signs of a shorted rotor shouldn't it?
The manual says all readings of P9 and P10 to A-F should all be high. A low resistance on any of them should be signs of a shorted rotor shouldn't it?
Must be the same thing. I'm looking in the TM procedure and it says P10, and the image on page 159 shows the plugs on the gen head being labeled P9 and P10...
These are the 2 main power output plugs coming off the gen head.
I'd assume the mating plugs on the AC reconnect box are J9 and J10.
These are the 2 main power output plugs coming off the gen head.
I'd assume the mating plugs on the AC reconnect box are J9 and J10.
Ah, as usual, you are correct! P10-A goes to X13A8 ground wire. There is a mistake on page 152 paragraph 2 on the right, winding resistance testing. It says P9 and 10 A-F. Should be P10 B-G with A being a ground!
Good work looking at the schematic Guy!
Now... back to analyzing Chris' other reading....
Good work looking at the schematic Guy!
Now... back to analyzing Chris' other reading....
OK, lets agree that 13-15 test are good to go.
Then test 10-12 should be good.
Test 1-3. You should get no continuity, between T1 and T2, or T2 and T3, or T1 and T3. They are not a pair. So they should be open. Those tests should be GOOD.
That leaves test 4-9. Here I see a problem,
These are the wire pairs, for the phases. T2 to T5 is NOT a good reading. I seem to remember that its a PITA to take these readings, and I had to do it several times to make sure I had the right pins. I would do this again, to be sure.
The J12 plug test is also good.
Then test 10-12 should be good.
Test 1-3. You should get no continuity, between T1 and T2, or T2 and T3, or T1 and T3. They are not a pair. So they should be open. Those tests should be GOOD.
That leaves test 4-9. Here I see a problem,
These are the wire pairs, for the phases. T2 to T5 is NOT a good reading. I seem to remember that its a PITA to take these readings, and I had to do it several times to make sure I had the right pins. I would do this again, to be sure.
The J12 plug test is also good.
When I did these tests back about a million years ago. We used a Wheatstone Bridge. Is a Multimeter made to todays standards, as good as a wheatstone bridge? I also thing the readings are to be taken at 25 degrees CELCIUS.
