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I came back down to the house. I don’t have very good WiFi in the shop. Just checking the schematics. 141A connects to TB4 terminal 16 from the A1, where it branches off to the J3 and to CR2. CR2 is the static exciter coil on the G1 I believe?

That’s high for sure.

My bad. 17.4vdc with S1 in run and 24vdc with S1 held in the start position.

360mvac is all I’m seeing across 1&3.

Ok, just confirming. Terminal 2 is open and the wire on terminal 3 is now labeled 2?

I also checked the continuity on the quad fuse, F1and F2 on the A1. All three are good.

Ok, I’ve got T1 completely disconnected. Now I have an under voltage fault, with no action on the frequency or volt meters. Nothing with S1 in the start position either.

That’s good news! So, just tape up the wires and remove the fried T1?

Well, something’s not good. I fired the unit up and adjusted the voltage. Then I reset the under voltage fault. It was sitting there running for about 15 seconds. (with no load) The engine stumbled a little bit and the short circuit light came on. I shut her down and saw this. The T1 is toast.😢

It did have the quad fuse, yes. I received the new A1 in record time, just installing it now. We’ve already established that my A1 is Libby. But I’m hooking up K5-1 & K5-6 and I’m seeing “Technology Research Components in here.🧐

Hello, I'm dealing with a similar problem on the same unit. I'm just wondering what ever became of this? Were you successful in getting it repaired? Thanks, Jeff

Thank you!

Again, I’m just wondering. Is the over-voltage fault on these machines related to the DC voltage or the AC voltage? It’s interesting to me that the unit shuts down on over-voltage but not under-voltage.

In preparation for replacing the A1 I went ahead and removed the old one. The only visible sign of anything wrong is the R5 which is located directly below the connections for the large capacitor. I connected my ohm meter to it and measured 2.36k ohms, but of course it’s still soldered in on the...

1) I recently had a under voltage fault on a MEP-804A 15kw unit. I thought that I should chronicle the event here in an effort to give back to this great forum. Forgive me if this post is a little long. I’ll label each paragraph and if someone wants to chime in you can refer to that paragraph...

This is a very detailed explanation of what you found. It’s what helps to make this an awesome forum. Great job!

Man, it's so much more pleasurable to trouble-shoot these machines inside of a heated shop that's well-lit with a cup of coffee and a little music. With your determination, you'll find the problem.

Has this unit been pressure washed?

Thanks again Kurt!

And, of course they don’t load test them. You may see a short video with a drill motor or something like that plugged into the convenience receptacle .