MEP-004a Setup and Startup

[reiters]

I need to double check but when I adjust the hz I think the volts are quite a bit low. I don't know where to turn the knob but I think it's around 70v where there should be 120v. I'm not sure if that helps you but thought I'd bring it up. I may try to crank it up tomorrow while recording on my phone so you can see exactly what is happening on the meters.

 

[Hard Head]

I have a Mep-004A and if the air exhaust louver switch acts up it will kill power and shutdown after a minute or so. You cannot adjust the frequency either. Operate the louvers and make sure they are open.

 

[reiters]

When I adjust the knob under the control panel it changes the frequency. The machine doesn't shut down it just only creates electric when I'm holding the the SRS in the start position. If I had a variac I could actually test the VR but I don't and not quite ready to buy one. I don't expect I would be needing it for anything else in the future. I tossed around the idea of going to a sx460 and be done with it but there is something about keeping it stock that I like. Maybe there is something out in the actual generator that is causing it to not make power. That's where it starts really going over my head. I have some background in electronics but it's been years.

 

[Guyfang]

Reiters,

That knob under the control panel IS the frequency adjust. The frequency adjust knob ON the control panel is for precise power sets! You have a Utility model.

 

[tcruwithme]

I also have an MEP-004A, but I started with a different set of problems. As Hard Head and Guyfang said, the frequency knob on the control panel will not do anything for the MEP-004A. The manual speed control knob under the control panel on the right side is the frequency adjustment, as Guyfang said.

Fear not, Reiters. You have Guyfang on the case, and that's better than Batman, Superman, and the entire Justice Leage working on your set.

Good luck with your project!

 

[reiters]

Here is a video. Not sure it will help but why not.

https://www.youtube.com/watch?v=RlAvL3aHsUM

 

[Guyfang]

Your hertz meter drops down, because the Frequency transducer, (the component that feeds the Freq meter) uses an AC power source. So as soon as your AC power drops off, the freq meter will also go south for the winter. If you hold S-1 up and adjust the throttle know, you will see the frequency go up or down. Do that one time and then leave it alone. Its good right there. This is a classic static exciter box problem. I would suspect the VR card. Hard to see from the video, but the remote and parallel switch is off, I hope. Lord, do I miss that sound! Could also be another reason I wear two hearing aids.

 

[reiters]

The reason I made several small adjustments is that I was holding the camera with one hand. Thank you for pointing it out though. Everything points to VR so I'll keep diging.

Sent from my SM-N900V using Tapatalk

 

[reiters]

So been a while. I ordered all new semiconductors for the VR. At least the ones I couldn't test with a good level of certainty in-circuit. Well 19 days later they showed up from China (long story - wasn't supposed to be from China). There is a DC voltage regulator on the board that as soon as I tried to solder it in one of the pins just fell off. It was defective. I must say I am very unhappy right now. I have ordered a new chip from a US (verified) supplier. It costs a lot more (5x) but should be here in 3-5 days. More waiting. I'm not good with waiting.

In the mean time I have done a lot of research on how the VR works and may come up with a different solution if this doesn't fix it.

 

[reiters]

I found this to be very enlightening. I was struggling to figure out how the AVR controlled the large current load. I understood how it was modifying the voltage.

http://portable.generatorguide.net/avr.html

 

[Guyfang]

I take it you were not in the military? Waiting is SOP. Every good soldier carries a book in his pocket!

 

[reiters]

I have not been in the military. It was more that I looked for a US based company because I didn't want to wait. Everything on their site was US including their address. After I ordered it took them 9 days to even ship the item and it was shipped from China. When I asked them about it they said "oh our warehouse is in China". I feel deceived and would have paid more and bought elsewhere had I known. I will take every opportunity to badmouth UTSOURCE that I can. The part cost $4 from them. I have since ordered it elsewhere for $10 + $9 shipping. I'm not afraid of paying for what I want but get very upset when lied to.

I am now leaning towards getting a SX460 and just going that route but I really wanted to be all original.

 

[reiters]

When I said it took 9 days to ship it, I meant it took them 9 days to put it in the mail and 10 more days to get to me. I am working on getting my $4 (woohoo) back from them. I don't care about the $4 I just want them to pay.

I got the new part today from the US vendor and soldered it in. IT WORKED!!! I was able to plug a space heater into the convenience outlet and get heat. I was able to get the right voltage and freq out of it based on the meters. I'll do further testing now that it's putting out voltage. Once it's all confirmed then I'll go thru the single phase conversion. I upgraded the parts when possible. The thyristers are rated for higher amperage and the IC is rated for a larger temperature range (not that it's needed). The real solution was U1 was burned out. I think it's what samples the generator output than compares it to the set voltage.

One thing I noticed is that the unit has a hard time with holding the voltage without a load. I don't know if thats normal. It bounces the voltage around and then turns it off. As long as it was under a load it was fine. I saw a YT video that said a lot of people burn up their AVR running without a load because the AVR cant sync the voltage and overloads itself. Lots more investigating to do.

 

[reiters]

So now that I know the genset works, I think I will convert it to single phase and replace the AVR with a sx-460. I wasn't overly happy with the stability to the voltage when running and I think I would be better off with newer technology. I understand I wasted $40 getting the old AVR functioning but I didn't want to buy a new AVR and try to install it and if it didn't work, wonder if it was my wiring or something else wrong. I needed to see it work first.

 

[Guyfang]

Sound reasoning.

I have not heard anyone complain about burning up AVR because of no load. But I haven't read all the threads in the forum.

 

[reiters]

Tonight was fun. I finally got to convert to single phase. Mine was a tiny bit different than the youtube video. My copper bar was on the bottom of the board and had all the wires over it. Made it interesting to cut. I used a dremel and cut it in place and then removed one nut to remove it. Otherwise I would have to remove several wires at once and increase the risk of making a bad mistake. The way I did everything, I never had more than one nut off at a time. I don't have a way to check the phases but I assume that nothing smoking after was a good sign. I will install the sx460 AVR tomorrow. I ran out of light. I did accidently cut one wire with the dremel but I soldered and heat shrinked it back. If I have the Hz at 50 the VR is stable but if I run it up to 60 it starts to get shakey and will fall to zero. I'm glad to have a new (modern) AVR for it.

So I'm thinking that a MEP-803a is more to what would fit my house. If I decided to sell this unit in know working order and low hours, what should I ask?

 

[reiters]

So AVR is in and works wonderful... as long as I manually flash the field. I plugged a corded drill in the convenience plug and gave it a little spin and everything comes to life. I was able to set the voltage and steady everything out. Works great until I shut it down. When I start it back up I guess their isn't enough magnetism left to get it going again. I may have to find a way to hook the old field flash back up without blowing the new AVR. I just don't know enough about the circuit to do that yet. If anyone has any ideas please speak up.

So close!

 

[Guyfang]

Magnetism is not what lights off the main gen. When the S-9-1 contacts reverse, voltage was sent to the exciter to light it off. When you hooked up your new VR, it must not include this function. So maybe you need to look at how you wired it up, and change something?

 

[reiters]

As I understand it, most household generators start producing because there is enough residual magnatism to create a small voltage that the AVR uses to power itself and "builds" the voltage from. I know these have a field flash built into the AVR which makes sense because you don't want to be out with the genset and have the magnetism drop too low and get no voltage. I had assumes I could use this unit the same way but it seems it doesn't store enough magnetism to do so. I measured 1.5vac from the unit without the regulator hooked up. It needs at least 5vac to get the AVR started. I wasn't sure if the field flash circuit in the original AVR would work without the voltage regulator hooked up too as they are tied together. I also don't want to fry the new AVR having the flash voltage/current fed into it.

 

[reiters]

So you gave me enough to move forward. The S9 (speed switch) controls all the timing and connections during startup. The main thing that frustrates me is that there is nothing I have found that tells me where the wires go then they leave the AVR. When I added the new AVR, I wired it completely eliminating the old one. I am taking the voltage directly from the generator head and directly connecting to the field windings. I now see that I may be able to leave the built in flashing system because the speed switch MAY prevent the AVR from being connected at the same time...which would fry it. Lots more digging to do now. I might have to hack into the original cables or rewire the original AVR. Something I was trying to avoid. The new AVR needs 4 wires and I was able to connect them via screws and no soldering. I can switch back to the old AVR by simply pulling the 4 wires off the new AVR and screwing in the 2 plugs of the old AVR. Looks like I'm not going to be able to do that.

Anyone know of a source for the plugs and sockets. I really don't want to cut wires.