Week Two – Electronics Production

Making the FAB ISP.

It’s been a long time since I’ve done much soldering, and man have the components shrunk. Or my eyes are going. Actually I suspect it’s both.

The Modela

Had some issues initially with cutting the traces on the circuit board – it started well, but faded, causing me to think initially that the retaining screws for the mill head hadn’t been adequately tightened. After a second attempt we realized that the sacrificial bed must have been sitting at a slight angle, sloping away from the reference point.

Worked fine after the substrate had been changed, and after a couple of mistakes concerning the software (namely my not being methodical enough). In particular, after changing the mill head to 1/32” and loading the new .png and making a new path, forgetting to hit “make .rml” before hitting “send it”.

Another significant learning is to make sure that the settings are for “Cut out board (1/32)” rather than “Mill Traces (1/64)” and that once you’ve corrected this error the path and the .rml file will need to be remade.

Stuffing and Soldering

Components were pretty straightforward, although a little difficult to read. I had been warned that the capacitors were unmarked so I made sure to keep them sorted.

Although surface mounted components are a little fiddly, it’s nice not having to turn the board over to solder. My joints were OK, but there’s plenty of room for improvement.

Next challenge occurred right at the end. I had deliberately over-soldered the USB connectors, with the intention of using the braid to remove the excess (trying to copy a technique I had seen Rob demonstrate). Unfortunately I got the timing wrong with the iron and pulled the copper tracks off the board, breaking the connection with the USB connector.

With a little delicacy I was able to rejoin the tracks to the connector.

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Programming

Connected it for programming but received the following error:

Considering the problem with the lifting track I’d initially suspect the USB connector. Used a multimeter though and there seems to be a good connection. There could be an issue with the capacitors (i.e. my using the wrong ones) but I’m pretty confident I kept them straight. I have cut out another board and selected the components, planning to make another. I think this may well be more time-efficient than troubleshooting, and I could do with more practice soldering.