Prototype Needed

After discussing it with Richard and Tommy, it was determined that we should produce a prototype board run to see if the layout and execution of the board was correct. The PCB123 company did not offer any cost effective prototype boards as the setup cost was a major part of the production cost. Setting up the etching masks and drilling templates was just as costly for one or two boards as for 100. So I went looking for other manufacturers of PCBs. I found several that offered their own CAD software as well as the low cost prototyping service (less than $100). I could not use the CAD design from the software that PCB123 had so I had to re-draw it in other CAD programs then error check it and submit it for price quotes. It turned out that it cost almost the same for 10 boards as for one from the final prototype PCB manufacturer!

Now time to order the materials to make the boards. I worked with three companies purchasing surplus electronic parts to make some prototype boards. The only drawback is that you might not be able to get the same parts for the later production run as surplus parts are just whatever they can get.

When the boards arrived I set off on assembling the 10 boards and after I finished the first one I plugged it into my simulator and fired it up to find that it did not work. Now comes the hard part, troubleshooting the circuitry and finding what was wrong. Since it was shorted, it was rather easy to find the defect in the printed circuit board. It turned out to be a connection on the original design that when I transferred it to the CAD software of this company, I shorted two foil traces together! Because the foils are on two sides of the board and the flaw was under some labeling on the board I failed to detect the error before making the boards. With some help from Tommy Cebulla we developed a fix for the short by cutting the traces and making a jump over the bad spot with a component lead. The other problem occurred to be that the red LED was on the wrong end of the board. If you orient the board with the connector down the red LED was at the top so I had to fix that as well. This was done by crisscrossing the supply resistors for the green and red LEDs and then installing the LEDs on the opposite ends. The prototype board is shown in the photo at the top of the page. We debated on how to connect the LEDs to the board and this is an attempt to make the connection flexible. Later versions use a rigid connection between the LEDs and the board. Now it is time to install some boards into service at the SCRR.