It's normal, and done in QC. Official business.
It's normal, and done in QC. Official business.
+1, I see it in all sorts of gear. QC.
I had nearly 20 years QA/QC. The caps are tested before assembly. I.e. the manufacturer may have had issues with lots received and q.c. verifies they meet spec. could be one or two values or just doing a 100% sort. Makes perfect sense considering the stuff we pull out today test good while others failed. All my stuff has a few or many marked caps. Includes; couple sony rec's. denons, realistics, couple of vcrs, and two pc's. One of which is a dell that has every cap inside marked.
hope it helps.
Another slant.. Go back in time say late 70's mid 80's and we're talking good brand name and your reputation rides on a high degree of reliable performance out of the box. You could expect to have a certain percent of failed field units because C160, C212 and C215 are known to be bad or fail way to early versus the 1000 hours of expected use. The authorized service center might get a bulletin updating the SM for same. So the unit comes in the shop and they mark the new caps replaced. This would be easily identified by a mark that can also identify work done in case the unit comes back in for something else. e.g. I have a couple shelved jobs that I know the caps have been replace and they are marked.
On a similar slant. You're an assembly facility and you build and pretest say 100 out of a limited run of 6,000 modelX. during initial testing they pass 100 hours of testing. Later on your dealer chain repair shops report that c160 etc. were bad. Oh shit you have 100 units at any point of the asm.line already built Okay you got to replace a crap load of caps.
Marked means tested or replaced. You have to mark caps tested to identify them from caps untested or replaced. I've even open wall rats to find the caps marked.
Similarly tech shops as noted mark them as others posted.