Edit: see comments for clarifications.
I am probably late on this one, but god damn this is one nasty trick by Philips.
Context; I recently decided to upgrade my shaver, from a Philips One Blade to Philips an all-in-one-trimmer-7000. As you can see on the pictures below, they changed the charger for the adapter by maybe 1–2 millimetres, just so the old charger could not be used by the old charger. Now, this normally isn’t a big deal, but with the new trimmer, the charger is USB-A only. Where’s the previous one had the plug on it instead. To me this is mildly infuriating as I know need to get an extra adapter just to charge my shaver in the bathroom. They had the exact same design for the chargers, yet changed it just slightly so they wouldn’t be able to be reused? Why… Philips… why?
Edit: many good points in the comments! I don’t know how to manually check the voltage, but seems like folks figured it out in the comments too. Should have just been USB-C!
Also the charger is required to show its voltage and amperage output ratings.
This is true, but something about being an Electronics Engineer makes you want to check. (I didn’t even trust Philips to get it right, but they did.)
I didn’t go into detail, but simple Dashed/Solid line doesn’t tell you the whole story. Those simple wall warts are not fancy switch mode, or even old school rectified. I measured 14VDC unloaded, which I can probably guestimate in experience, to be a 9VDC loaded reading.
The actual reading on wallwarts are generally untrustworthy, unless its a thing from Samsung or apple, where the circuitry are what you would expect (switched etc).