loosegravel
Just a retired mechanic who's having fun!
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My bad. 17.4vdc with S1 in run and 24vdc with S1 held in the start position.
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MEP-804A Under Voltage Fault
- Thread starter loosegravel
- Start date
loosegravel
Just a retired mechanic who's having fun!
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That’s high for sure.
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24 is way to high.
Disconnect the wires from VR terminals 1 and 3. Measure the resistance between those two wires. It should be 28 to 38 ohms. This is checking continuity to and the resistance of the static Exciter coil.
Disconnect the wires from VR terminals 1 and 3. Measure the resistance between those two wires. It should be 28 to 38 ohms. This is checking continuity to and the resistance of the static Exciter coil.
loosegravel
Just a retired mechanic who's having fun!
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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?
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CR2 is not the static exciter coil. CR2 is just a diode in the circuit that provides the flashing voltage to the static exciter.
F- and F+ shown above go to the VR terminals 1 & 3 and then on to the static exciter via P5 pins 28 & 29
F- and F+ shown above go to the VR terminals 1 & 3 and then on to the static exciter via P5 pins 28 & 29
loosegravel
Just a retired mechanic who's having fun!
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Ok, I know that it's getting late for you. Tomorrow is another day. A fresh cup of coffee in the morning will get me motivated to start doing some more continuity tests. I did ohm the 141A and 140A wires with them disconnected from A1. That's open. I then checked terminal 6 on the K15 and 141A. Thats good. I also checked 140A to terminal "F" on the J3 diagnostic plug. That's also good. I need to follow up tomorrow with some more tests. Thank you so very much for your help! Jeff
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LG,
I would find me a terminal strip, and screw it down were the T1 was. Hook the wires up there, in order. Why? Because in 10 years you or someone else may want/need to put this thing back together like it was once was. But to just tape them off and leave them hanging is not a good idea. This way you can restore some order, make it look good, AND always put it back the was it was.
I would find me a terminal strip, and screw it down were the T1 was. Hook the wires up there, in order. Why? Because in 10 years you or someone else may want/need to put this thing back together like it was once was. But to just tape them off and leave them hanging is not a good idea. This way you can restore some order, make it look good, AND always put it back the was it was.
loosegravel
Just a retired mechanic who's having fun!
- 504
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- Location
- Enumclaw, Washington
I was going to run some continuity tests on the J5/P5 today, but something else came up. I’ll report back when I do.
loosegravel
Just a retired mechanic who's having fun!
- 504
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So! Some good news for a change. 
But first, before I divulge the reason that this unit was not getting 10VDC across terminals 1 & 3 after the new A1 was installed (was actually getting 24vdc with S1 in the start position) I must say something here. I was once told by a wise, older gentleman that you can't save your face and save your bacon at the same time. You have to choose one or the other. And, since this forum has saved my bacon yet once again (al the TM's and the schematics) I feel that it's my civic duty (I say civic duty because I was never able to get into the military...long story, another thread) to divulge this information in spite of how I will look bad. But I strive for complete transparency so here it goes.
In post #10 I fired up this unit after I replaced the voltage regulator. I was able to adjust the voltage up some and I reset the under-voltage fault as described in the installation instructions. In about 15 - 20 seconds of run time, I witnessed lots of smoke coming out of the compartment where the T1 transformer is located. I immediately shut the unit down and went back to disconnect the batteries. Upon closer examination I could still see where the smoke was coming from. It was the T1 transformer. (My word they sure do pack a lot of smoke into those things!) Again, this wonderful forum clued me in on this thread that with the new A1 voltage regulator now installed the T1 transformer (and a few other components) is no longer needed. That was relief for me! I could see more $$$ coming up in my dreadful thoughts, not to mention some potential down-time and more labor. And since this T1 looked crispier than a marshmallow that fell into a campfire, I wanted to remove it and clean the soot from that compartment.
Here's where my face is going to look bad. The (7) wires that also went to the T1 were all very crispy as well, up about 4" from the T1. I know what Guyfang said in post #27, but I didn't want to leave any crispy wires behind. So, I cut everything that went to the T1 transformer back about 6". Here's my mistake. Wires 140A & 141A from the A1 voltage regulator ultimately end up at TB8 as wires 140D & 141D. This is simply a two terminal board which is located right above the T1 in that compartment. That's where the F1 & F2 wires begin. (They're black wires) But wires 140D & 141D were zip-tied in parallel with the other (7) wires that originally went to the T1. When I cut those wires back, I actually cut 140D and 141D also. This was where my open circuit was to the A1 terminals 1 & 3.
In my older years, I'm finding it more difficult to see like I used to. I usually always wear a headlight on my forehead, and I have additional battery powered lights with magnetic bases on them that I stick inside of these compartments. But inevitably when I make a mistake like this it's simply because I could see what I was doing. They talk about "CRS" a lot and thankfully I haven't been stricken YET. But I'm definitely getting a case of "CSS!" I just picked up my new prescription glasses the other day. I didn't try them on in the optometrist office. (My bad) I went next door to get some things from the hardware store and I put the new glasses on before I walked in. I was thinking "right on...these are nice!" That is until I tried to look at the tags on some products. I absolutely couldn't see anything up close. I left the hardware store and went back to the optometrist office where I nicely shared my dilemma. The Dr. came out and said that they made a key mistake. They didn't make these glasses "bi-focals". I'm glad that they took back, and I'm glad that I still have my old ones which are working fine. I'm also happy that I'm not the only one who makes mistakes! Thanks again to this great forum, and I sincerely hope that someone gets something out of this! Jeff
But first, before I divulge the reason that this unit was not getting 10VDC across terminals 1 & 3 after the new A1 was installed (was actually getting 24vdc with S1 in the start position) I must say something here. I was once told by a wise, older gentleman that you can't save your face and save your bacon at the same time. You have to choose one or the other. And, since this forum has saved my bacon yet once again (al the TM's and the schematics) I feel that it's my civic duty (I say civic duty because I was never able to get into the military...long story, another thread) to divulge this information in spite of how I will look bad. But I strive for complete transparency so here it goes.In post #10 I fired up this unit after I replaced the voltage regulator. I was able to adjust the voltage up some and I reset the under-voltage fault as described in the installation instructions. In about 15 - 20 seconds of run time, I witnessed lots of smoke coming out of the compartment where the T1 transformer is located. I immediately shut the unit down and went back to disconnect the batteries. Upon closer examination I could still see where the smoke was coming from. It was the T1 transformer. (My word they sure do pack a lot of smoke into those things!) Again, this wonderful forum clued me in on this thread that with the new A1 voltage regulator now installed the T1 transformer (and a few other components) is no longer needed. That was relief for me! I could see more $$$ coming up in my dreadful thoughts, not to mention some potential down-time and more labor. And since this T1 looked crispier than a marshmallow that fell into a campfire, I wanted to remove it and clean the soot from that compartment.
Here's where my face is going to look bad. The (7) wires that also went to the T1 were all very crispy as well, up about 4" from the T1. I know what Guyfang said in post #27, but I didn't want to leave any crispy wires behind. So, I cut everything that went to the T1 transformer back about 6". Here's my mistake. Wires 140A & 141A from the A1 voltage regulator ultimately end up at TB8 as wires 140D & 141D. This is simply a two terminal board which is located right above the T1 in that compartment. That's where the F1 & F2 wires begin. (They're black wires) But wires 140D & 141D were zip-tied in parallel with the other (7) wires that originally went to the T1. When I cut those wires back, I actually cut 140D and 141D also.
This was where my open circuit was to the A1 terminals 1 & 3.In my older years, I'm finding it more difficult to see like I used to. I usually always wear a headlight on my forehead, and I have additional battery powered lights with magnetic bases on them that I stick inside of these compartments. But inevitably when I make a mistake like this it's simply because I could see what I was doing. They talk about "CRS" a lot and thankfully I haven't been stricken YET. But I'm definitely getting a case of "CSS!" I just picked up my new prescription glasses the other day. I didn't try them on in the optometrist office. (My bad) I went next door to get some things from the hardware store and I put the new glasses on before I walked in. I was thinking "right on...these are nice!" That is until I tried to look at the tags on some products. I absolutely couldn't see anything up close. I left the hardware store and went back to the optometrist office where I nicely shared my dilemma. The Dr. came out and said that they made a key mistake. They didn't make these glasses "bi-focals". I'm glad that they took back, and I'm glad that I still have my old ones which are working fine. I'm also happy that I'm not the only one who makes mistakes!
Thanks again to this great forum, and I sincerely hope that someone gets something out of this! Jeff
- 16,793
- 24,144
- 113
- Location
- Burgkunstadt, Germany
I sure hope you dont think you are the only one to have done something like this. I could write a book.
loosegravel
Just a retired mechanic who's having fun!
- 504
- 892
- 93
- Location
- Enumclaw, Washington
I appreciate that! All of the old sayings that we heard when we were younger are so true. "If you can't laugh at yourself, then you're in a world of hurt!" And I've also found that allowing others to get a laugh at my expense isn't all that bad either. I hope you're feeling better Guyfang!