"Missing" large caps

[N9JIG]

In reviewing some pictures of the inside of my 536 (http://forums.radioreference.com/uniden-tech-support/283316-bcd536hp-discriminator-inside-look.html) for another reason I noticed spaces marked for C504 and C508, which look like they are intended for a couple very large electrolytic capacitors.

At first I thought maybe it was held over from the previous BCD996XT but photos show a different board design (see http://forums.radioreference.com/un...273947-under-hood-shots-my-hot-rod-996xt.html).

Any ideas or guesses as to what these would have been for and why they were labeled and not installed? I imagine there are other components also not included in the final release but these stick out like a sore thumb.

 

[Voyager]

Did you have the RTC mod done?

 

[N9JIG]

Not at the time of the pics. It is at Uniden now for the repair along with my 436.

 

[byndhlptom]

Missing caps?

It's been my experience in the design process....

You often design a circuit with extra filtering/parts you "think" you need. Then after verification that everything works, you can go back and see if you can reduce parts count/cost. It's easier to delete a part (and not change the artwork) than add one(s) after (requiring a new artwork spin if significant) you have most of the work done. I've done that (especially around power supplies & regulators).

Also, you may have needed xx amount of capacitance, when you spec'd parts you needed two (or three) due to mechanical restrictions, then by the time production rolled around, you could get the same capacitance in a smaller package (or more capacitance in the same size).

Sometimes designs change and you don't need a circuit, so you just delete the parts on the BOM, but don't change the pcb.

$.02