| Electronics > Beginners |
| Inverter as a boat anchor? |
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| james_s:
Do you have a heat gun like the type used for thawing pipes and stripping paint? With care that can give you all the heat you need. |
| jerryk:
I don't have any cast iron pans around but have considered using ceramic tile in a pan to mimic the uniformity of cast. Of concern is those three diodes (type and temp tolerances unknown) on the back of the board. I thought of straddling the two tiles to keep the diodes from direct contact of the heating surface as an option. I do have a real nice heat gun that I can use to supplement the preheat process. I also have a fluke laser temp 62 max and the temp probe from my multimeter as temp monitoring options. I suppose heat just from the bottom of the board? The overheating the blue filter cap bank on top is a concern of mine. I looked at the datasheet and the only temps listed are operating temps with the max being 105C. Surely they can take more than that in a preheat but how hot can I get them without causing damage? I really want to replace the yellow ceramic caps but not sure on how to get an exact match or even if that is important. I think they are a 2.2uf MLCC but the C5K has me stumped. (Edit: added better shot of front and back of caps) The biggest concern of all is the close proximity of the drain tabs on the two rows of IRFS3004's. I'm interested in any type of soldering technique to keep the replacement row I have to install from bridging to the adjacent row. The only thing I can think of is to put a piece of kapton tape over the tabs on the existing row. As far as solder type and technique goes, should I use solder paste or should I pre tin the pads an try to melt them in that way. Any tips on type of solder or any experience you guys can share before I make the plunge would sure make my day. Thanks for all the help so far. Jerry |
| jerryk:
I just wanted to follow up on this thread to say I might have fixed this thing. I'm waiting on the control panel to arrive so I can do some detailed fault checking. I have yet to put it under any real heavy load but the inverter produces a very nice sine wave and runs a small 3amp ac motor. The charger seems to go through all phases of charge without a hitch. So I'm on pins and needles an know that I'm aways from putting the "FIXED" stamp on it. One of the disappointments of the whole thing is because I'm in Alaska I can't get any conformal coating or thermal transfer epoxy without a very long shipping wait. I found a conformal coating pen which I will touch up critical areas but the thermal transfer epoxy I think is fairly important. I have attached a picture of the placement of the epoxy on the inverter board and am wondering if there is any off the shelf stuff that will work. The only stuff I have found at our electric supply place in Anchorage has aluminum in it and would mess up the 100k thermistor reading as far I know. Lastly is there any sort of conformal coating substitute hanging around the average hardware store that I might be able to sub for the real stuff? Otherwise, I really appreciate the help and am a little blown away that it's working. I also attached a photo of the end of the repair and hope this thing passes the test of time. It's been fun - Jerry |
| james_s:
Maybe an automotive clearcoat paint, transparent epoxy enamel or varnish? I'm not e chemist but I would think some paints would do a reasonable job of keeping moisture out. |
| CatalinaWOW:
You might also go really old school and dip or paint with molten beeswax which should be locally available. It is certainly not as good as modern coatings, but better than nothing. Also relatively easy to remove. |
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