seanadams;213860 Wrote: > Do you think I forgot to tell my guys to solder them in there or > something? > > Although I'm sure you are an expert in RF and have designed many > products of your own for worldwide compliance, I will explain anyway > for the benefit of our other readers. > > When designing complex PC boards, it's a good idea to put pads for > series elements wherever feasible on power and IO lines. Then when you > test the system for emissions, you may need to experiment with chokes, > ferrite beads, resistors, and caps to identify and suppress specific > sources RF. Often this process takes several weeks and many board > spins, since you can't always just cut-and-jump the changes. That's why > you need to put the pads in - you can't just wire these parts in by hand > and expect them to perform the same way. When the board is ready for > production, you don't go back and remove all the unused pads. There > would be no benefit to doing that, and you actually would run a > significant risk of changing the characteristics of those traces or > otherwise introducing some new error. These extra pads are referred to > as "NP" for "not populated", but I'm sure you knew that. If you look at > pretty much any circuit board you will see places for parts that are not > there. That does not mean that the designer "messed up". It means that > the part could be installed (or not) for any number of reasons, not > just EMI but also feature differentiation between products sharing the > same PCB, configuration bits such as an IRQ or clock speed, alternate > footprints for second-source parts, and so on. But again, I'm sure you > design circuit boards all day long and you know all of this. > > So back to the case in point: in all likelihood, unless you actually > tested your modifications it is quite possible that you have created an > EMI problem where there was none before. But what do I know - I only > "DESIGNED" it, right? > > So, now that I have answered your questions, would you kindly answer > mine? Thanks.
Sean, When I received my first Transporter, The first thing I done was plugged it in to my bench power bar. Without realizing, I had a noise sniffer plugged in the same power barÂ….. Do need I say more? I popped the cover of the transporter, and found to line filters was omitted from the design. Further investigating, I realized that the package size of the filter components was incapable of handling the amount of current the transporter required. So instead of redesigning the whole Pc board to accept properly sized filter parts, they was jumperÂ’ed and shipped, as is. So if anyone is looking for a "Validated Mod" Install a HQ dual stage line filter in between the IEC and pc board. The one I use has world wide compliance built in to it. This can be the reason why "your" line filter was ommitted from final design. ;c) So your theory of "I created" is tossed out the window.. :c) Anthony -- aberdeencomponents ------------------------------------------------------------------------ aberdeencomponents's Profile: http://forums.slimdevices.com/member.php?userid=1234 View this thread: http://forums.slimdevices.com/showthread.php?t=36626
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