Working on a motion control board that has failed. I have sourced one small SMD cap that is showing shorted? Seems odd to me but I am no pro with this. Is a shorted ceramic cap a typical failure mode?
We have another identical board and I was going to compare the boards but I was curious, SMD resistors seems to follow a coding process but do capacitors by chance to identify them?
Beware when "experts" use words like never and impossible. It is difficult to prove a negative, as the following pictures will attest. At some point resistors are simply too small to mark but those in the pictures are 0805 components. I believe 0603 resistors are marked as well.
On the other hand, *I* have never seen 0805 or 0603 capacitors marked with values - I'm not sure why they are not.
My experience is that surface mount caps (which I assume are MLCC's - generally buff/brown in colour) are awlays unmarked. I don't know why; it's pretty annoying.
If you've an identical board then you're in luck as you should be able to measure the equivalent known good cap on that board. You can *probably* (maybe with a bit of informed guesswork) get a measurement in-circuit.
I also agree with dknguyen - it's my understanding that MLCCs (multilayer ceramics), at least, are quite prone to failing short. In fact I read an app note recently (and I appologise that I can't find a link to it now) that painted them as quite unreliable all round, and also prone to failing open or low value.
The "take home" message for me from that app note was that the way that they are soldered/mounted has a significant impact on the reliability, so I now avoid reworking them when I can. If I do have to, I'll re-flow with hot air rather then hand solder with an iron.