MEP-004a

[reiters]

Well gentlemen, I am back. Been away for a few years. Everything has been working on my generator relatively well.

Recap. I have a mep004 that I converted to 240/120 and eliminated the VRM and replaced with a SX-460. At the time I also added a relay so that when in "start" it would use the built in field flash and when released it would fast switch to the sx460. All worked fairly well.

Lately I'm having issues keeping the sx460s working. I can start the gen and as soon as I release the start the voltage will spike to 400 on the dash and it will shut down due to over voltage.
I am fairly certain that if I replace the VRM again that it will work again for a time. I assume it's the flash field collapsing that it nuking the vrm. I need to come up with a cleaner and more proper solution. I assume I don't really need to use the stock field flash and relay with the sx460. I think the sx460 should handle all of it if wired properly.

Does anyone know the best way to remove the old vrm/exciter altogether and use just the sx460 without my rigged relay? I don't mind a little effort or a little money to get it working long term.

Thanks in advance. I know you guys know these things inside and out... literally. I will be your eyes and hands but please be patient. I am a computer nerd with some electrical experience. I am not a mechanic or even smart.

I am in NE Texas if anyone is in the area.

-Keith

 

[Scoobyshep]

Well gentlemen, I am back. Been away for a few years. Everything has been working on my generator relatively well.

Recap. I have a mep004 that I converted to 240/120 and eliminated the VRM and replaced with a SX-460. At the time I also added a relay so that when in "start" it would use the built in field flash and when released it would fast switch to the sx460. All worked fairly well.

Lately I'm having issues keeping the sx460s working. I can start the gen and as soon as I release the start the voltage will spike to 400 on the dash and it will shut down due to over voltage.
I am fairly certain that if I replace the VRM again that it will work again for a time. I assume it's the flash field collapsing that it nuking the vrm. I need to come up with a cleaner and more proper solution. I assume I don't really need to use the stock field flash and relay with the sx460. I think the sx460 should handle all of it if wired properly.

Does anyone know the best way to remove the old vrm/exciter altogether and use just the sx460 without my rigged relay? I don't mind a little effort or a little money to get it working long term.

Thanks in advance. I know you guys know these things inside and out... literally. I will be your eyes and hands but please be patient. I am a computer nerd with some electrical experience. I am not a mechanic or even smart.

I am in NE Texas if anyone is in the area.

-Keith

At a glance I question the rating of your regulator, its spec sheet indicates that it is for a field of 15 ohms minimum, your field is 2 to 4 ohms. It might be too small.


I did something similar with a 005, and needed to parallel 2 regulators to keep the field up.

Sent from my SM-G973U using Tapatalk

 

[reiters]

Interesting. Is there a better one out there? Am I right that I shouldn't have to use the stock exciter and a relay. My failing memory is that it doesn't generate enough voltage with out the exciter to trigger the sx460 to kick in. I think that is why I took the route I did.

 

[Scoobyshep]

All you really need is 24 volt momentarily on the field to start the process. I cant recall what the factory flash is.

Sent from my SM-G973U using Tapatalk

 

[reiters]

I think I tapped 24v in the control panel when the SRS was in start mode then the replay switch to avr once I switch to run. I see the spike then so I assume its the field collapse. Maybe my relay is getting dirty and not switching...hmmm

 

[Scoobyshep]

While you have the flash energized, meter the output of your avr.

Sent from my SM-G973U using Tapatalk

 

[reiters]

I am going to mess with it in the morning. I think I will first test if the avr is dead. I'll start the gen in battle short and then use a hand drill to excite the field and see if the avr picks it up and runs. If it does then it's something to do with how I'm doing the switch. When I first tried to get the avr to work I tried just hitting the field with 24v while the avr was connected which quickly blew it up. Most of the cheap avrs require 5v to start working and these gens dont make any until you excite them. Maybe I can hit it with a much lower voltage than 24 but enough to get the 5v needed at the avr. I really don't want to add a button on the front to manually excite it after startup but I will if needed. If I did that then I would fully start the motor and have zero output and then just bump a button that applies a few volts to the field while the avr is connected but not enough to blow it.

 

[reiters]

I finally got around to checking and the voltage regulator is still working. It's just the spike during changover that is killing engine. I figured out I can start it with battle short then switch it off after engine is running and it actually started producing power. I measured the field voltage while it was running and it was 19vac. My idea of putting a little "starter" voltage on the field wont work because the plan was DC from the battery. I guess I can put a diode inline so the ac doesnt feed back. I will do some playing around when its not raining and muddy.

 

[Guyfang]

You can not start the set in battle short.