mep803a was generating power to home but not now

[Retired Wood Guy]

Hi I am new to this invaluable form Steel Soldiers but not getting lost chasing rabbit trails.
Short story. Generator worked flawlessly 3 years ago for Hurricane Ian.
I shut down after 30 days in 2022 October.
I had been cranking every few months to keep active.
I needed home power about 4 months ago and set would not generate power.
I printed the TM 642-24 and started the eating procedures and following all you guys on the post.
I have tested S5 a couple times. one test good. one bad. i tested again for 3rd time and its good.
I also tested S5 diode between points 2 and 5 and did seems in right direction and tested ok.
I have power to the convenience receptacle
I bench tested the K1 relay and it had to be helped closing.
I have a new K1 relay from Callie colt.
I installed and it will not close in while running the set.
I do not believe I am getting 24 volts to y on K1
I read on this form to check the terminal plug where it goes through the panel and spray with contactor spray cleaner and re connected.
my 3amp td fuse next to ac interrupter is good.
I have written down all my testing but am now getting weary and in need of help.
Thank all of you fellas on this Form. It has been so helpful at finding out what my problem is not. I haven't hit the problem yet but hopefully with help I will.
Bob

 

[Scoobyshep]

Hi I am new to this invaluable form Steel Soldiers but not getting lost chasing rabbit trails.
Short story. Generator worked flawlessly 3 years ago for Hurricane Ian.
I shut down after 30 days in 2022 October.
I had been cranking every few months to keep active.
I needed home power about 4 months ago and set would not generate power.
I printed the TM 642-24 and started the eating procedures and following all you guys on the post.
I have tested S5 a couple times. one test good. one bad. i tested again for 3rd time and its good.
I also tested S5 diode between points 2 and 5 and did seems in right direction and tested ok.
I have power to the convenience receptacle
I bench tested the K1 relay and it had to be helped closing.
I have a new K1 relay from Callie colt.
I installed and it will not close in while running the set.
I do not believe I am getting 24 volts to y on K1
I read on this form to check the terminal plug where it goes through the panel and spray with contactor spray cleaner and re connected.
my 3amp td fuse next to ac interrupter is good.
I have written down all my testing but am now getting weary and in need of help.
Thank all of you fellas on this Form. It has been so helpful at finding out what my problem is not. I haven't hit the problem yet but hopefully with help I will.
Bob

If it's just not getting past the contactor the good news is it's a fairly simple control circuit just have to figure out what is not allowing it to close.

By the way Geneva Florida as in right next to Sanford?

 

[Retired Wood Guy]

yes
My 2 sons in Army (retired) grew up here In Geneva.
1/2 way between Sanford and Titusville

One of the last things was tracing was the x and y on k1
I pulled of wire leads x and y just to make sure the new K1 i installed was working. It was and working.
I had 24v dc on Y. I don’t remember if closed the the s5 or not but I think I closed the s5 to check For 24 dc Reading.
I feel like the X on the K1 is the negative, Am I possibly correct?
The X on the K1 goes to the K20 oil pressure relay.
I had a new one so I replaced for good measure.
I checked the diode CR1and CR3 and the values and they were good.
Going to call it a night.
Thanks for any advise

 

[Ray70]

If I recall correctly, X and Y are just the switched leads for the illumination bulb +. I think 24V power comes into X and when the K1 contactor closes it allows 24V to pass through to the illumination bulb.
11 and 12 are the + and - that control the K1 relay itself.
12 being - and 11 being + coming from the switch, passing through K8 ( the Over Load / Short Circuit relay.
You can check this with a meter to verify continuity from 12 to battery / chassis -
To test the K1 ( with the engine off ) you can simply remove the wire from the 11 terminal and put a small wire from 24+ and touch it to the 11 stud on K1 and you should hear a loud CLUNK if K1 closes.
If it closes consistently I would call K1 good.
If it doesn't always close you can try opening it to clean it internally.
If it does not close at all I would suspect it is stuck. A few whacks from a rubber mallet while K1 is powered from the battery may free it up, but if it does, that still indicates K1 probably needs to be cleaned inside. If not, K1 has bigger issues internally.

 

[Retired Wood Guy]

OOPS
I meant to say I am getting overwhelmed chasing rabbit trails. I believe I will stick with Steel Soldiers.
That will cut down on my confusion.
Possible Hurricane in Atlantic now so I will go over TM 642-24 trouble shooting methodically now.

Short Story is Mep803a worked perfectly in 2022 October
Set cranks and runs well
110v ac at conv. plug
AC interrupter switch not closing and lite not coming on
no power to main lugs
I am in urgent need of advise
Thank You all
Bob

 

[DieselAddict]

Be sure to get the updated DC schematic.

MEP-802A, MEP-803A Wire Lists and annotated DC Schematic

To facilitate tracking down electrical issues with the MEP-802A and MEP-803A I put together 3 PDF's and a page of notes. 1) PDF document is a table of all the individual wires in the MEP-802A and MEP-803Aand is sorted by wire number 2) PDF document is a table of all the individual wires in the...

steelsoldiers.com

 

[peapvp]

Question,
Since you got 120V on convenience receptacle, do you you have power on lugs when you hold S5 in closed position while Genset is running?

 

[Light in the Dark]

Your problem will likely come back to the K1, or wires going to it.

 

[Retired Wood Guy]

I Just checked and when I closed the S5 No Light No Power to the L1 L2 L3
I checked the Ground fault breaker at the Panel face with Genset running. GFI tripped as it should No power to convenience receptacle. Hit reset and power back to receptacle, but not to L1 L2 L3 No voltage. I wanted to get back to you asap
BUT tried one more thin I read in the Mep803a threads.
They mentioned holding the Master switch for 10 seconds after the Gen cranked. I am not in the habit of holding the key switch on anything for 10 seconds past the time the engine cranked. I thought I would try to hold Master Switch for at least 10 seconds longer.
and
Everything on my MEP803 has came back to life. S5 I heard close in. AC Circuit lite came on and is staying on.
120v on L1 120v on L3 240 volts between L1 and L3

Last week I ordered a K20 Relay (oil pressure relay) and thought I would put in for giggles. Last week I had no success and everything I was checking was good. Last thing I did Saturday was to install the K20 and try the S5 (ac circuit relay) and it did not close in, so I gave up for the day.

Today I cranked to be able to answer your question. The only thing I did different was to hold the Master Switch Longer. Everything worked as normal.

The takeaway with all this is My K20 oil pressure was bad. With the new one installed AND me holding the Master switch for 10 more seconds, I am back in working order. (to back verify the old K20 I put back in and nothing worked)

I thank all of you for all your expertise and prior post. I have read many of them and was loosing faith in my Mep803a.
Now because of you guys I have been renewed.
Kindest Regards
Bob the retired wood guy.

 

[Light in the Dark]

If you had power at the 120v outlet, the extended cranking shouldn't have done anything... The field was excited and the genhead was making power the whole time. Perhaps you got lucky and some corroded item found a path through it, but I don't think your problem is 'gone'.

 

[peapvp]

A General note:

The easiest way of checking if K20 is working is by observing M3, the Hour Meter while Genset is running.

Off course this requires the Hour Meter to be operational in the first place.

Both circuits, for K1 Terminal X and Hour Meter Terminal + get their +24 V Supply from K20.

So, without even using a VOM or DMM, K20 can be ruled in or out.

This leaves then only the K1 Terminal Y to chassis ground.

In this scenario, by just simply holding S5 in close position, the simplified trouble shooting continues:

1. K1 activates, but drops off as soon as S5 is released back to center / resting position, then the problem lies solely in the Self Holding Contact 11 and 12 of K1 or Diode CR 3 or K8 SC / OL Contacts

2. If K1 does not activate while holding S5 in close position, then the problem is from K1 Terminal Y all the way to S5 Switch Terminal 5 and from Terminal 6 to chassis Ground.

 

[Guyfang]

A simple way to see if K1 will close, can be done without starting the set. Push in CB1. Place the S1 in the run position. Place the S7 in the up position. Push up S5. Will the K1 close? You will hear a thump, and DS7 will light up.