Companies that sell high-end equipment like JBC (and LeCroy) have no excuse for installing anything but top-brand caps IMHO. It’s shameful to find no-name (or even just mid-tier) caps in a supposedly premium product.
As for flux residue: ehhhhh… as a perfectionist I also like to deliver pristinely cleaned boards. But pragmatically, there is no reason to clean residue like JBC leaves behind, and there are good reasons not to clean. As long as it is rosin or no-clean flux, then it’s safe to leave behind. These aren’t sensitive RF circuits, and the easy, quick ways to clean PCBs (like ultrasonic) aren’t necessarily good when you’ve got connectors and cables/wires, which is what they’ve hand-soldered. In a
white paper about white residues, Kester (the solder manufacturer) says this about cleaning rosin flux (which applies to no-clean as well): “Typically rosin fluxes, including most activated types, have insulation resistances in the 10
10 ohms or higher. The problem arises when it is required to remove the residue either because the assembly will operate hot (above 65°C) where the rosin becomes tacky, or the rosin might flake off and get between electrical contacts, or just for aesthetics (
not a good reason for cleaning).” (Emphasis mine.) It also mentions that “Rosin, with its high insulation resistance, keeps the halides dormant but if the rosin is removed, leaving some halide salt behind, corrosion is possible.” This means that incomplete cleaning is
worse than no cleaning at all.
The solder joints that are not fully filled are suboptimal, but given the type of flat-flex they connect to, they aren’t carrying any significant currents, and heating too long could damage the flat-flex, so erring on the side of “get in and out quickly” is probably wise. It certainly isn’t going to malfunction or fail prematurely due to those solder joints. The important joints are the ones to the circular connectors, and they’re fine.
P.S. Your teardowns are legit interesting, but your weird nonstandard capitalization* and frequent run-on sentences make your blog posts much, much harder to read than they need to be!
*Capitalization isn’t a form of highlighting of important words. In English: First word in a sentence, and then proper names/titles only.