A Lousy Way to Deal With Parts

Twenty years ago, I sat at a bench at a new job. The products were timers and controllers, and one day, I grabbed some dead units and started to evaluate them. In looking at the schematics, I found a rather bizarre situation -- several 10K resisters were labeled R1. I thought that this might be due to some lazy CAD driver, and that they were probably hand drawn. At Tektronix, we refer to PCB layout drawings as dolly sheets. I looked at the dolly sheets, as well as the silkscreen on the board, and I was horrified. All components with the same value had the same nomenclature.

I talked to the designer, and he told me this was done to make the hand-stuffed-through-the-hole parts easier on the assemblers. I guess he was assuming a high yield. However, reality says human error creeps in on monotonous and repetitious jobs like stuffing PCBs by hand day after day.

I started to work on the boards, but I had to trace every node as if there was no documentation available. Thankfully, these were only two-sided boards. Since 10K is probably the most used value of resistors, R1s were all over the place.

I kept to myself on this, since I was a new guy. I didn't want to ruffle any feathers. Over several months, I did a lot of trace following. The only benefit was that I didn't have to check the bill of materials when a part was missing. It turned out the parts were binned as R1, R2, C1, etc., as well. So all I did was check the silkscreen and fetch the part. Neat, right? No way.

One thing that is missing in our industry is standards. But even with standards, some folks feel autonomous enough to do really goofy things. Stories like this make this field of endeavor rather entertaining.

This entry was submitted by Steve Lindberg and edited by Rob Spiegel.

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