MEP-831A Inverter Cleaning

[g2reeves]

All,

Thanks to all for previous advice with my MEP-831A unit issues. While Hurricane Harvey rages outside, I've been tinkering with, and gave up on, my second MEP-831A and started parting it out. I wanted to keep its inverter as a spare for my running unit, but noticed dirt caked around the voltage selector switched and decided to open the case and take a look. It's filthy, full of Afghanistan or Iraqi or maybe just good old west Texas dirt and I'm wondering if there's a safe way to clean all this gunk out. In high school electronics class we had spray cleaner to remove soldering residues and the like and wondering if I can do the same to this. It's been in my house for two years without making power, and who knows with GL before that, so I trust the capacitors will have lost charge by this point. Any thoughts would be appreciated!

 

[DieselAddict]

If it were me I would clean it with either deionized or distilled water. I know that may sound unusual but water will not harm the circuitry. After you wash it with very clean water go back and rinse it with 70% IPA. That will help remove residual water.

Give it a good inspection and make sure that the coating that has been put on the boards is still in good shape. If it looks as if you have cracks or peeling in the surface coating you will be susceptible to moisture issues in the future from moisture in the air.

 

[g2reeves]

Thanks, Diesel. Still raining outside, I'll give it a shot. I've got both distilled water and isopropyl alcohol handy.

-G2

 

[g2reeves]

Thought anyone following this would like an update. Got the case apart (the case is nicely made, but ridiculously complicated for what it is, IMO) and didn't do any additional disassembly. I flushed better than a cup of super-fine reddish dirt out. It's been flushed with ISA and is now drying. I didn't identify any delaminations on the boards, but I can't imagine the thing's going to work again, with all that dirt it probably has burned out pieces somewhere that got hot. I'm very surprised there was no filter for the fan that cools the inverter.

 

[DieselAddict]

I bet it will work.

 

[Dwnorton1]

The location of the inverter cooling fan is in location that will certainly allow wind blown dust to be picked up easily. I wonder how many inverters we burnt up by this fresh air port be obstructed by something. Would have thought "do not block" would have been stenciled on this port just to raise awareness.




View attachment MEP-831a.pdf

 

[coxju04]

following

 

[g2reeves]

The location of the inverter cooling fan is in location that will certainly allow wind blown dust to be picked up easily. I wonder how many inverters we burnt up by this fresh air port be obstructed by something. Would have thought "do not block" would have been stenciled on this port just to raise awareness.

Yes indeed; the updraft fan is close to the ground where it can pick up all kinds of junk then and pushes air and dirt through the heat sink and then up into the box itself. I've never had reason to take the inverter out of my working unit so this was quite a surprise. Surprising also was that the fan, despite all that dirt, seems to be in good shape. I may try to figure out some kind of filter for future operations of my working unit. Mine doesn't get moved with a forklift so I may have a little extra space to work with for a high flow filter like a K&N or something similar. Given the high cost of replacing these inverters when they fail, I would think keeping them clean should be a high priority.

 

[g2reeves]

Update for anyone following: After getting it all dried out, I got everything put back together without any leftover parts or cracked circuit boards . Next up is an operational test in my running MEP-831A, maybe next weekend. I'm also searching for a good filter solution for the inverter inlet and will post back once I get something together that will work.

A few notes for anyone in the same situation: The case for the inverter has a number of difficult to see spot welds that may prevent much disassembly. A couple on mine were missing, allowing me to get a bit better access. I highly suggest labeling the outside case pieces so you don't have to guess during reassembly, and also to take note of which size hardware goes where. There were at least 3 different hardware sizes just for the case itself, and there are warnings about having too-long hardware and damaging the circuit boards. Also, the big capacitors in the middle of the unit are all glued together, forming little cups in the middle of each group of 4 that hold lots of debris and need a little help to get clean. I'd post a picture, but it was impossible to get a good shot that would make any contextual sense. Otherwise, it's just a set of boards and capacitors, nothing really to troubleshoot unless you have some advanced diagnostic capability.

-G2

 

[NATCAD]

Can any cleaning be done via vacuum with generator blocked up at 30 degrees on the inlet at bottom

Will a shop vacuum induce any static electricity that could be a problem to vacuum inside inverter box

 

[g2reeves]

I don't think a vacuum would do you much good; the bottom of the inverter is a large billet aluminum heat sink that'll block the force of the vacuum. That said, it might be better than nothing. A shop vac will produce static, but I don't see that as a problem as long as the unit is grounded. The inverter box is all conductive aluminum and bolted to the generator housing, so I have to imagine it would disperse any harmful static easily. These were built to run in the desert with low humidity and flying dust, which is a perfect recipe for static discharge. Hope this helps...

 

[boatman69]

A piece of brown scotch bright is what I use for a filter. Think anything finer might hurt the air flow.

 

[Contractor Jackson]

DieselAddict, so with this moisture issue regarding these inverters is there any way at all to prevent the moisture? I have a few generators I am working on currently that are having the same moisture issue. I took the inverters apart and recoated them with conformal coating spray and I am still having the issue of moisture. It only occurs in the mornings when there is a fair amount of dew in the air and the gen set won't produce voltage when this moisture issue happens. After a couple hours when the outside air temperature rises the gen set starts and runs just fine. Have you heard of guys putting the boards in an oven and does this work? Or covering the blue pots (potentiometers) with silicone? Does this work? Or what can I do to make this issue stop?