MEP-004a Setup and Startup

[Guyfang]

Partner, I am not an E&E. There are plenty of them in the forum, maybe someone can help you with it. I am just a poor old generator mechanic.

I would assume, and that's a darn good way to get your butt in a crack, but I would assume, the speed switch would prevent the two functions from being engaged at the same time.

 

[reiters]

Thanks!

I may just give it a try. The AVR was $25. Right now the genset is an expensive boat anchor making my front yard look redneck. If I fry the avr then I'll just grab a new one. I know which pins on the old avr control the functions but I don't know if I can simply unsolder the old wires and hook them to the new avr. I think I need a diode inline to prevent the flash voltage from wiping the new avr. I got an electronics degree from a votech 30 years ago but havent used those skills so I'm not that great at it.

I REALLY appreciate all the time you've spent responding. You really have sent me in the right direction several times.

 

[Guyfang]

We try to do our best!

 

[reiters]

I finally started doing some educated guessing. I just cant find the information I need. I have now blown up my sx460. Not that it's the end of the world but I am frustrated. I tried wiring it in with a diode in place but wasnt sure how I should connect it. I ended up just using a full wave bridge rectifier to try and make it fool proof. I was the fool. I decided to wire it streight to f1 and f2 and it popped the scr. I'm to the point I need my trailer back, so I don't know what I'll do next. I know I can wire it so I can plug in a drill to excite it but I dont wanna be doing that when there is a storm out and the power cuts off. I can probably put in a extra button that runs a relay as an "excite" button but I was hoping to leave the dashboard stock. Any suggestions are most welcome at this point.

 

[Guyfang]

Do you know anyone who has a silliler gen set? If so, borrow a static exciter box, and put it in your unit. Try it. Its the only way I know to find out if the problem is in your VR sub system. You have bought and changed and tested and replaced so many things now, its hard to keep track of it all. I went back to the start of this thread and read it all though about 7 times. It still sounds like you need to just toss in a static exciter box, and try it. I assume you are still using at least some of the static exciter box? It has two functions. Excitation and volt regulation. The exciter seems to work. It lights off the main gen when you hold the S-1 up. The holding of S-1 in the up position bypasses almost all the safety functions. I do not believe you have ever said what happens, when you let S-1 drop down. You said the voltage stops being produced, but will the engine continue to run?

 

[reiters]

Right after I got the sx460 I removed the stock AVR. Unscrewed 2 plugs and physically removed it from the genset. Wired the sx460 streight to the field and 220v. When I cranked the genset it runs great. No output. When I measure the output at the 220v its 1.5vac so not enough to get the new AVR going. If I plug in a corded drill and manually spin it while holding the trigger, it excites it enough to start up and it produces a nice steady 220vac (after initial pot adjustments). I count that a minor success. Next step was to see if I could make it work without the manual drill trick. When I hook up the stock AVR (2 plugs) but remove the VR internally (1 plug) it will run the voltage up to 50vac as long as I hold the SRS up but fall to zero upon release. I tried combining the stock exciter and new AVR together to see if I could get the best of both worlds and that's when the sx460 blew a thyristor.

I am tempted to add a momentary toggle that when on trips a relay the feeds 5vdc from one starter battery thru a resistor to limit current to excite the field and then when released kill that and let the AVR swoop in and take over. More complucated and I would have to modify the stock control panel.

 

[Guyfang]

I am tempted to add a momentary toggle that when on trips a relay the feeds 5vdc from one starter battery thru a resistor to limit current to excite the field and then when released kill that and let the AVR swoop in and take over. More complucated and I would have to modify the stock control panel.[/QUOTE]

That's what the S-9-1 contacts do.

 

[reiters]

I'll try to decipher if I can use that to do what I need. I have a really hard time figuring out the wiring based on the manuals. I only have 20 minutes here and there to look at it so I don't get to trace the wires manually. I have an electonics background and can read a schematic no problem but I don't know where wires are going when they leave the AVR. If I could figure out that, as an example, where does the wire from j13(L) go when it leaves then I could start to make sense of it all. If I remember correctly, the S-9-1 is the speed switch. I looked at the diagram for it and it made total sense HOW it works but I don't know what wire goes where. I need to tap in somehow that the sx460 has no connection while the SRS switch is up and then removes the exciter when the SRS is in run.

 

[Guyfang]

J-13, terminal L goes to P-55, then to TB-6, terminal 9. See fold out 1-page 4.

 

[reiters]

OK so j13(L) was just a made up example BUT page 4 of what? I have 4 PDFs and the first several pages are always a bunch of repeat junk

 

[Guyfang]

In TM 9-6115-464-12 are the schematics and wire diagrams for the MEP-004. Go almost all the way to the back of the manual.

 

[reiters]

So I finally had some time and ambition to work on the genset again. I ordered a new sx460 since I fried the other one. I ordered a nice 24v 10a DPDT relay. Took 24v off the SRS switch in the start position to trigger the relay. So the sx460 is hooked up to the 120vac and the relay. The stock exciter is hooked to the relay. The stock VR board has been removed from the inside of the AVR box since it didn't work. So now when you hold it in the start position the relay connects the stock exciter to the field. When you release the start switch it drops the relay and now the sx460 is connected to the field. From the outside of the machine you would never know it's been changed. All controls work normally except the voltage adjust knob that isn't connected. I preset the voltage on the sx460 and I assume it will stay stable. If not I will route the pot to the sx460 allowing voltage adjust from the panel. I was going to put a diode across the sx460 field wires but I couldn't find my diodes so I just risked it and it went fine. The only issue might be the collapse of the field after the exciter causing a reverse voltage spike to the sx460 when it connects. I really think its minimal risk so I'm just gonna let it go.

 

[Guyfang]

Well, test, and retest. If its good to go, then onward and upward! Sounds like you are done!

 

[reiters]

Today was wiring and test day. I wired the genset to the house with 6 guage wire into a 60 amp breaker. I know it's not a transfer switch but I'm not ready to spend that kind of money yet. I switched off the main breaker of my house and on the 60 to the genset. I kicked the gen on and double checked the voltage and frequency. Switched on the load and the genset took over fine. I then turned on the dryer, stove and put a cup of water in the microwave for 2 minutes. Checked the genset and it was humming along at 80% and would spike to 90% when the microwave would cycle. I am very happy with the results. The voltage and frequency didn't budge during all the loads. I run my generators fro 15 to 30 minutes each month to keep them going good. Typically I plug in a 1500w heater as a load during this time. That isn't enough load for this unit so I will use the house as a load on this one. I'll run the dryer so it can get nice and hot and I don't think I'll have any wet stacking issues. Thanks all and especially Guyfang for the advise and encouragement.

 

[87Nassaublue]

Congratulations on a job well done. I know that makes you feel good to have that project behind you.