Building the power supply pcb

Today we work on populating our second of three PCB’s: the Power Supply Board. This will be a fairly brief account since we’ve seen nearly all the required building techniques before.

Here’s the board itself with the resistors installed. These are of the somewhat more challenging, surface mounted variety: bend and trim the leads, tin the “pads” on the board with solder, then hold the resistor in place with a pliers (or if you’re brave, your fingers) and heat the tinned pads so that the solder you applied to them melts and the resistor is fixed in place. My fingers were a little shaky this time so this isn’t my most aesthetically pretty resistor install, but functionally they should be fine.

IMG_0205

Next you install a variety of electrolytic capacitors on the other side of the PCB. These are all polarized: the negative terminal is indicated on the capacitor body with a stripe, and the positive terminal hold is marked with a “+” on the PCB, so it’s not hard to keep the proper orientation straight!

IMG_0206

Next comes a little technique we haven’t seen before. Using little bits of insulated wire, you create links in three spots on the board; two are surface mounted, one pokes through holes in the board.

IMG_0207

Here’s a fuller view of the finished resistor side of the board:

IMG_0209

And we’re done! Here you can see the two completed boards more or less in position inside the chassis, although we won’t be screwing them in place until the interfering is complete:

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One more PCB, the Filament Board, left to build. We’ll do that next time!

Until then…

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