I bought a vintage amp, the caps have sharpie dots on them.

JoshHendi

^ElectroNerd^
I bought a vintage amp, the caps have sharpie dots on them. I am guessing that this is a method used by 'recappers'? Im guessing they mark the original caps so they know which ones are original and to be replaced? or something along these lines?

Any info or input?
 
I put red sharpie marks on top and over towards the positive lead. Then I take pics so that I can verify orientation after the caps are removed.

Occasionally I have seen a few existing marks on (what appear to be) original caps. Possibly marked by someone troubleshooting or considering replacement? I don't know.
 
I used to do that when making a cap list. Now I just pull them all and record the size and position on paper. Easier to read once they're in my hand.
 
Its a "mystery"?

Markings a mystery:scratch2:?

I once chased bad caps with markings in a power panel for a flat screen television. I was told, the bad caps are marked. Unfortunately, all were marked with either a dash or the like.

Replacing the suspect cap, did not solve the issue and the marked caps were fine. Not sure what the gist of putting markings on something without a legend or "universal" meaning ...but its fustrating where board components are concerned:thumbsdn:.
 
I have seen this, too, also on transistors.
I think it was my Pioneer SA8100, I found all differential pairs transistors marked, so maybe they were hand selected.

Other reasons one might think of are rejects or missing components during production and then marked when inserted or replaced.

Also, in the past sometimes times components were tested before use, if it is full of marked caps those may all have been tested..
 
I mark them before replacing, but mostly as a quick visual clue to make sure I haven't missed any. I use whatever color marker falls into my hand first, but I go through and dot them as I record the values for my cap list. Once I have all the marked caps out, I'm done changing parts.
 
I mark them just to annoy people and keep them guessing ... :D

Ditto on marking before recaps though. I mark them as I add them to my buy list, then scan for marked caps after a board is done to make sure they've all been replaced.

Lot of times you'll see them fresh from the factory - usually some sort of quality check like making sure they're polarized correctly.

No rhyme or reason on used equipment though ... we all have our ways.
 
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.
 
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.

OK so you have a board assembly facility. They buy in volumes too low to force the vendor to do the screening. So they test incoming shipments of capacitors on a 100% basis or an audit basis and mark the ones that passed. What's the point in marking the good ones? Why not just toss the bad ones into a scrap bin and use the good ones without marking them?

I could understand it if they were QC'ing the inspectors themselves and putting "Inspected by 49" on the inspected caps. That way if they found any bad "Inspected by 49" caps in warranty returns they could go to Mr. 49 and rip him a new one. Flesh this out some more please.
 
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.
 
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.

OK that all makes sense. I was thinking along the same lines that a marked cap is a cap that had drawn an unusual amount of human scrutiny / intervention. That's why I was thinking it was related to a scrap / salvage activity in which the cap was identified as bad, replaced, then sent through end-of-line testing a second time. If the board failed a second time then the sharpie mark would indicate that the cap had previously been replaced.
 
I mark them when i restore one, for photo proof when i ebay them due to scammers. (I also do a lot of other stuff)

this isnt one of my units is it?
 
Back
Top Bottom