Fried Power Supply

The original fuse (white tube) after cutting away black heats hrink tubing.
The original fuse (white tube, bottom left) after cutting away black heatshrink tubing.

As a public service message, I feel obliged to share the following nugget of wisdom: before plugging a tower computer into a 220V outlet, reach around to the back of the computer and make sure the input voltage select is 220. Sounds simple, right? This isn’t something you have to think about for most laptops, which have dual voltage power supplies. They are happy plugged into either voltage and the power supply brick just works.

I’m not [arguably, perhaps] an idiot – I was aware of the switch. I just thought that the power outlet was off, but also I didn’t expect to encounter an issue until the computer itself was turned on. Wrong — ATX switching power supplies are always on. When I plugged the computer in 220V, there was a popping sound followed by smoke from the back of the unit. Never a good sign.

I pulled the power supply out, opened it up, and looked around. Nothing was obviously charred. My nose has lousy spatial resolution — it confirmed that something wasn’t right, but couldn’t help me localize the problem. I followed the wiring from the outlet inward. For a cheap supply, I was glad to see some decent capacitors on both live and return wires to ground, and across them. Also, some inductors to quell EMI. Next in line: the fuse. It had blended in because as a safety precaution, it was wrapped in heat-shrink. I cut away the heat shrink to reveal a white tube. I couldn’t see into the fuse, but my continuity tester showed it had blown. There was no fuse holder; the fuse was just soldered in by its leads, so I dutifully unsoldered it.

Continue reading “Fried Power Supply”

First Big Storm

Friday afternoon, a “moderate tropical cyclone” swept west-to-east across the Island. It was a big enough storm to get a name, Chezda, and I’d been watching it on satellite pictures for a couple days. In the last afternoon, it hit the west coast, bringing rain and wind. This is what it looked like. It’s the swirly cotton thing on the left. The more ominous looking storm on the right is another one, Bansi, that wasn’t a problem for Madagascar, but did affect Ile Rodriques. It is headed southeast, so not so much of a concern.

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Since the picture was taken, the center of Chezda has moved off the east coast of Madagascar, but not before dumping a lot of water yesterday and blowing fiercely overnight. Many low-lying areas were flooded. We’re a couple weeks into the rice harvesting season, and in this area, it looked like only about half the rice had been harvested, so I would guess some crops might have been lost to inundation.

There were a lot of power fluctuations yesterday, but as far as I can tell, no major damage in the local area. The wind died down the the sun came out around ten this morning. I’m pleased to report that aside from a bit of water around the garage door, no water entered the garage. The improvements to drainage happened just in time.

The storm is predicted to continue to move south-east and should miss the populated islands in our region.

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More Garage

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Water in the garage. This is a problem.

In the previous post, I mentioned that our shipment from the US came in several large wood crates, just as the rainy season started. I had a lot of boxes of radio gear, tools, and other items that needed sorting and I wanted to work in the garage, but since the garage is built below ground at the end of a down-sloping driveway, I was worried that the garage floor could not be trusted to remain dry. As the rainy season picked up, I soon found that this concern was justified, as the french drain in front of the garage could not cope with the run-off.

I had a few of the bottom pallets from the shipping crate; each sits about 8 cm above the floor on wood blocks. I moved these to the back of the garage (since the floor slopes towards the front where the drain is) and piled everything on top of them, while I considered my options.

Although it is rainy season, most of the time it is not actually raining. Most of the water in the front of the garage would run out almost immediately, and the floor would often be dry a half hour later. Unfortunately, the receding water would always leave behind a fine red mud, or after drying, dust.

Making some sort of raised flooring seemed like a good idea. Unfortunately, the plywood used in shipping crates is of very poor quality and only about a cm thick. I could walk on it, but it would groan and sag. However, I had a lot of it.

Fine, government-quality plywood.
Fine, government-quality plywood.

I spent the next couple weeks disassembling all of the crates, pulling out the useful two-by lumber. I must have pulled out thousands of nails — most of which I was able to straighten and use again. I remember the day I packed out in Virginia: it was also raining. The moving guys covered the crates in copious amounts of plastic wrap. The corollary is that both the framing lumber and the plywood were chock full of staples. I painstakingly yanked them all because I was paranoid that I might hit them with an electric saw later in this process.

I piled up the lumber, trimmed off bits that were too damaged to be useful, and played a constant game of shifting around unpacked boxes, lumber and tools, to get at the materials I needed while still keeping everything high and dry.

Since the plywood was so thin, I added some reinforcing cross members to the lumber framing and then tossed another layer of plywood on top, laminating it to the existing plywood with some locally purchased wood glue. Between the wood glue and additional nails, the double-thickness plywood made a solid floor. Still a little creaky, but no real give.

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Two of the pallets support a table on the left and a pile of bricks on the right. Note the red stain on the floor, where water had accumulated transiently.

The water never got more than a centimeter or so high in the garage, but I didn’t like the idea of wood blocks sitting in water. This set up has to last four years or so.  I needed some kind of solid, water-resistant material to serve as supports for the wooden feet below the platforms. Not surprisingly, I obtained locally produced bricks. Bricks are very common here — they are produced from rice paddy mud between crops. They are not the best quality bricks as they lack binding materials and fiber; they are just baked mud. They are relatively fragile to shocks, but resilient to compressive force. For my application, they worked fine, and the price is right: 80 ariary each (about three cents a piece).

So, in boosted the existing flooring up, with two bricks under each supporting wood block, and then fabricated some additional flooring so I had covered the rectangular middle portion of the garage. The back of the garage is strangely trapezoidal, so I put that off for a bit.

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A view from the back of the garage looking towards the door (which is down).

I needed a place to work and also some storage, so I made some work benches. I more or less followed a design from a YouTube video for a bench that looked very solid. I already had an Ikea table, which works best at a sitting height, so I made the benches to be used while standing. Like the floors, the benches are made out of wood recovered from the packing crates (although I did top one with some nicer, sanded plywood that I had shipped for that purpose).

Going back to the source of the problem, drainage, I had some workers clean out the drain area at the left end of the grill, above. I hadn’t realized how much silt had collected. They reamed out the pipe downstream as well. I watched the drain during the next heavy storm and was pleased that it had no problem diverting the water as fast as it came.

With less worry about moisture, I decided to install a short carpet in the central area of the garage. The addition of the carpet made it feel much more comfortable. Next came the rolling office chair.

Finally - some storage. All those tiny parts!
Finally – some storage. All those tiny parts!

Finally, I set up the Ikea shelfing and was able to unpack the many boxes of hoarded electronic bits and pieces. I still have some unpacking to do, but I am now able to get to everything: patch cords, adapters, tools, etc., which will let me get going on station and antenna set up.

The first project for the new workspace: construction of an antenna panel to bring coax into the shack through lightning arrestors and antenna switches. Other projects on a near infinite list include finishing the back portion of the garage and installing some storage shelves for larger items, working on the mount for the hex beam antenna, and fabricating some additional antennas.