Yep, going through some old threads while looking at a box of players that hadn't been out in a few years. I know I had some decent Sanyo's and Toshibas from back when I could find them for a couple bucks. I did it, I'll admit it, I left some batteries in. Here's what a few years of rotting batteries will do... And these were in mint condition when I bought them....
They both had the plastic cover with the flocked lining, I think the flocking helped spread the acid...
Shame on you sir... We've all done it. I have to admit that I left batteries in my beloved NOS boxed Sony F2. It breaks my heart to think of that. Currently in southern Italy with Leonardo
Could be worse, I documented my repair attempt of a DC2 which slowly turned into a slasher film... I happen to enjoy Metallica, Master of puppets isn't that bad, just a tad aggressive, which is perfect for pulling all-nighters.
No fun whatsoever. I had batteries leak in my Casio CZ101 keyboard after deliberately leaving them in to keep the sounds in memory. They weren't even flat but leaked onto the circuit board. After about three time consuming repair sessions, none of which stayed working more than three months I decided I had to sell it Spares or Repair to stop myself from wasting any more time and got £20, a fifth of what it was worth working Even more expensive was the Wireless Central Heating controller which cost £120 to replace after the batteries leaked over the summer. Annoying Bosch have changed the design for the worse so the new one is less convenient to use. That had Duracells in it so the weren't no name rubbish (unless they were fake). In contrast about a year ago I bought a Sharp calculator at a car boot sale. Although it is working perfectly I decided I had better check the batteries. 1983 (which ties up with the age of the calculator) but still going strong with no signs of leakage.
Had bought this one, in this condition, because of the somewhat rare black color and a couple of weeks ago started to clean it just to see how extensive was the damage . It seems it has some hope to bring back to life but a lot of work also , it is impressive how the acid was dissolving copper under the protective paint. Note that most of the damage (naturally) is just under the battery compartment area.
If all it did was rot away the copper it would be possible to replace that with wire links. The problem I had with the Casio was that it seemed to have soaked into the circuit board making it conductive enough to mess up the operation e.g play one note and get two. I spent hours cutting tracks at each end and replacing them with insulated wire, but as noted in my last post, each time I fixed one fault another would appear a few months later.
Most certainly that's how the acid found its way to the printed circuit, through the circuit board, from the batteries side. Actually the circuit board on the battery compartment is heavily discolored from brown to almost black. I'm not super optimistic about it working again, it just has a chance.
I guess you could gut it Machaneus and turn it into a flask.... https://gizmodo.com/5872464/5872464/walkman-flask-holds-other-kinds-of-mixes
I don't think I would drink or eat anything inside from that walkman ! Besides the poor wm f75 has suffered enough from the various liquids especially that one that was designed to prevent liquids from getting into it !
I am too embarrassed to show what I had mistakenly left batteries in. I did bring it to the shop to have it repaired, but it was too far gone to repair. I had a number of good years playing it before I executed it by lethal injection of acid. Nando.