MEP-802A No Power

[robconcep644]

Hi everyone,

I have replaced the ac regulator after conducting the tests in the service manual. With the new ac regulator installed I am getting the same incorrect readings. Could it be a diode in the generator head or should I look elsewhere? The voltage, power and hertz indicators all read flat. All other indicators work properly.

Thanks Robert

 

[Light in the Dark]

Hi Robert. Has this machine ever run properly for you? Can you tell us specifically what you have and have not done, and any other operational conditions to help derive an answer for you?

 

[robconcep644]

Hi Light in the Dark,

The gen has been running perfectly for the last year. Other than changing the ac regulator and the aux fuel pump, I have not changed anything on it. It suddenly stopped producing power. I have done scheduled oil and filter changes. The electrical appears original. The ac regulator voltage tests show very low voltage results. Wire 104c and terminal 5 test reads only 1.6vdc instead of 8vdc. Terminals 7 & 8 reads 6vac instead of 67.5vac to 87.5vac. Terminals 3 & 4 read only 3.6vac instead of 108vac to 132vac. The potentiometer is reading correctly. Any insight you have is greatly appreciated.

Thanks Robert

 

[Light in the Dark]

Silly question... but have you tested for power at both the lugs and the convenience outlet?

 

[Guyfang]

Stop. First, troubleshoot.

The Main gen can only make power if it gets excitation.

The main gen gets its excitation from the S1.

Go to the S1, pin 7. Start the set normally. Keep the S1 in the start position. Measure at pin 7. Get 24 volts? If not, S1 is not good. If you get 24DC, then let go of the S1.

Test the 120 volt outlet. Are you getting voltage? If its about 24V, then the exciter isn't lighting off the main gen.

You have tested your Quad fuse for continuity?

 

[Light in the Dark]

Stop. First, troubleshoot.

The Main gen can only make power if it gets excitation.

The main gen gets its excitation from the S1.

Go to the S1, pin 7. Start the set normally. Keep the S1 in the start position. Measure at pin 7. Get 24 volts? If not, S1 is not good. If you get 24DC, then let go of the S1.

Test the 120 volt outlet. Are you getting voltage? If its about 24V, then the exciter isn't lighting off the main gen.

You have tested your Quad fuse for continuity?

Not just a pretty face, folks! For as much as the TMs help us owners, its always nice to get real pin point testing knowledge from those with deep experience. Thank you as always Guy.

 

[robconcep644]

Hi there,

I will check S1 and the quad fuse. Also I did test the lugs and the outlet, no power on either.
Thank you for your help.

Robert

 

[robconcep644]

Hi Guyfang,

Pin 7 of the S1 reads 21.2V. The quad fuse has continuity. The power ac outlet reads 5.8V. I hope this helps the diagnosis. Any extra help is greatly appreciated.

Thanks Robert

 

[Guyfang]

Sorry Its been a while. Life is jumping here.

Have you taken K15 and K16 out and swapped them?

Then I would look in the -24 TM for the test procedure for the exciter stater.
1. Turn to PDF reader page 213. There is a simple description of how the main gen works. Below is the resistance of the exciter stater leads, TABLE 4-1.
2. Below that is the test procedure for the rotating diodes, Paragraph 4-10-3. Do the test.
3. Below that is the test procedure for testing the Exciter stater, para 4-10-4. Do the test.

And just keep on going, if need be. I don't think its a VR problem, as the initial exciton should come from the S1. If that doesn't happen, then you need to dive deeper into the excitation process. None of these tests are real hard.

The voltage at pin 7 on the S1 is a bit low, but should still be more then enough to light off the main gen. If you hole up S1, does the starter grind?

 

[robconcep644]

Hi Guyfang,

I will perform the tests that you recommended. If I hold the S1 the starter does not grind. I believe that the S1 voltage is low because the batteries may be a little low. Again I give you a huge thanks. I'm still getting to know this generators electronics.

Thanks Robert

 

[Farmitall]

Hi Guyfang,

I will perform the tests that you recommended. If I hold the S1 the starter does not grind. I believe that the S1 voltage is low because the batteries may be a little low. Again I give you a huge thanks. I'm still getting to know this generators electronics.

Thanks Robert

Always start any troubleshooting proceedure with fully charged batteries if possible. All DC measurements are based on that.

 

[Light in the Dark]

24V devices don't always provide reliable performance sub 24V...