SMD Soldering, My First Try

I finished my first kit with SMD parts, the Mcount kit from Jackson Harbor Press, and it works too. It was very satisfying to hear the device sound out FB when I applied power. For the first power application, I ran the current through my DVM to make sure the power draw was OK. The Mcounter said FB and the milliamp draw was within reason so I connected the battery directly to the board. Again, FB. Frankly, I don’t have any equipment to calibrate the counter so I don’t have any idea how accurate it is. I connected the probe to my previous project, the NorCal Marker/Generator at pin 9 which is supposed to pulse at 5.120 MHz. The Mcount reported a very close 5,120.2 KHz. I’m calling that a success. To be honest, I don’t know for sure if the pre-scaler circuit works or not. Later, I’ll key up my old HT and see what the Mcount reads. I bought the complete set of options including the off-board parts and the punched, empty candy tin. Squints again but a different set of flavors, therefore a different color tin. Thank goodness the candy was not included. Nasty stuff. Here is the complete project, with the hood up:

mcountdone450.jpg

I see why some folks shy away from soldering SMD parts. Before I tackled the Mcount kit, I took an old controller board from a hard drive and de-soldered some SMD parts then soldered them back on for practice. Somewhere online, I read that you should take a shot of the soldered SMD parts with a digital camera and zoom in to inspect the connections. I remembered that brilliant idea after soldering on the through-hole parts. After a close inspection, I carefully cleaned up the joints on the two chips. At 10x through a magnifying glass, I could not get nearly close enough. On the computer screen, the photo has enough detail to make those little pins as big as my thumb. This photo (reduced for the web) is a before shot:

mcountsmddetail450.jpg

During my first attempt with SMDs, I learned that I should not have cut corners on the type of solder I use. The 0.032 size is too big. I’m ordering some smaller stuff with a 63/37 mix. While my eyes are young enough, and my hands are steady enough, I’m going to keep building kits with SMDs. As a result, the number of interesting kits available expands significantly.

Download a nifty little pocket reference for operating the Mcount that I threw together for this project from the construction documentation. The file is an Adobe PDF. Print it and fold the document as described at PocketMod.

Play the text of this article in Morse code!

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