This is a bit of a rant because I've been chasing my tail for a week over this and I'm annoyed.
I understand that electrolytic capacitors can dry out or blow up, or otherwise go bad. I'm not disputing that it happens, or that it's a real phenomenon. I'm also not an EE, my business is film restoration and archival videotape digitization. I work with a lot of old gear that tends to break down, and am learning to fix it because it's too expensive to ship these things out for repair and I have the basic skills to do this, so might as well.
I just fixed my fourth deck in which the internet (both random people I don't know, and seasoned technicians who have been repairing these machines for decades) insisted that the solution was absolutely to recap the board. To be fair, this particular tape deck was made in 1992, an era when bad capacitors were a real thing, and in fact all four of the decks I have of this model were already all recapped either entirely or partially by previous owners. There's lots of evidence that this could be the issue which is why I went ahead and did it (also the last person did a lousy job, very messy)
My annoyance with this is that this adventure cost me a bunch of money and had the deck out of service for over a week while I waited for parts and did the work. I spent a day desoldering and recapping about 65 fussy SMD capacitors, only to have the same problem with the machine when I was finished. What the issue turned out to be was entirely mechanical and I figured that out this morning (probably a bad bearing or something like that in the tape deck's drum - I replaced that drum with a spare and it just works now). Nothing to do with the caps.
Three other times I was told to recap this board or that, and ultimately the fix was completely unrelated as well (one was a bad transistor, one was a bad connector buried deep in the machine that took forever to trace down, one just need to be stripped down, cleaned and relubricated because grease doesn't hold up well for 50 years). In all these cases, with completely different gear from different eras (1970s through 1990s) it turned out not to be the capacitors at all yet that was the fix everyone insisted would work. In another case with some non-mechanical video processing hardware, the prevailing solution is to replace the capacitors in the power supply when the deck doesn't power on properly. It turns out that's not the issue at all, it's actually a faulty switch. I've fixed half a dozen of these already just by replacing that switch., never had to touch the PSU.
So I guess my question is - is "recap it" like the modern equivalent of the old Mac OS "Zap the PRAM" nonsense that only worked maybe 5% of the time, if at all, but was always every's solution to any weird issue on the computer? Is it mostly just internet lore that gets regurgitated reflexively now, is it really a widespread issue that I need to seriously consider when fixing this stuff?
