My sewing machine is over ten years old, used heavily almost daily and probably 5+ years past the bullshit intended lifespan.
This model is not sold anymore, replacement parts are not manufactured anymore and the few still available are horribly overpriced accordingly. I can and have repaired the MECHANICAL portion of it numerous times, but without detailed instructions, the electronics might as well be magic...
Today, the potentiometer that determines the LCD display contrast fucked up. The manual doesn't list it's specs. The super duper secret repair manual doesn't list it's specs. No specs are printed on it.
I tested it with a multimeter, but that only gave me a reading between "this is too much resistance" to "this is WAY too much resistance", since - ya know - it fucked up and even the lowest setting nearly blotted out the display.
So, being left with "less than this, but not zero?" the ONLY component I had available that did the trick was a shitty 20mA yellow LED... Which being a diode shouldn't even work like this, but fuck if I know what the board of my sewing machine actually expects this circuit to look like. I am equal parts confused and frustrated.
So now I have a very confused 5¢ LED living inside my sewing machine, acting as the most jank resistor(?!) imaginable.
No wonder Succession Wars era Battletech appeals so much to me.
I too am reliant on lost technology, trying to frantically keep it working without documentation, replacement parts and only a passing understanding of how it even works.
