I’ve fixed three PB100s.
Two of them had a SMD resistor, 420k I think it was, that had gone open circuit - near the display cable connector on the logic board. This caused a no-backlight scenario.
The black-LCD scenario (i.e. all pixels black) is usually caused by the ~30V drive voltage not being present, in turn caused by the inductors being corroded near the trackball connector after the capacitor leakage in that area.
I’d love to say - send them my way
but I live in New Zealand so it’s a long way to post.
I really like these machines; much better than all the other Powerbook 1xx machines (never get any broken hinge plastics or screw standoffs; actually nothing breaks), I love their rounded shape to the screen casing compared to the square shape of the others, they’re nice and slim, and I run mine off NiMH batteries.
I’m working on a Portable at the moment and it’s a nightmare in comparison…