Internal NiCad for sure. It's also possible/probable that the electrolytic caps are failing. Multiple caps in mine (the 1uF ones - the smallest) had failed and peed acid onto the circuit board when I came back to it after many moons. It was bad enough to sever the trace that brought the LCD bias to the display, resulting in a zero-contrast condition. At this point those electrolytics are 40 years old so recap is an excellent idea.
On a tangent about the caps... the march of Progress has brought solid state MLCCs within easy reach of all the capacitances up to about 1uF. Just saying, MLCCs age far more gracefully (they DO age though, the high K dielectrics undergo a phase change that's reset by soldering temps), and an 0805 is just the right size to fit across two .1" thru hole pads... -- Erik On Tue, Sep 23, 2025, 6:53 PM John R. Hogerhuis <[email protected]> wrote: > Yeah if it hasn't been replaced it's probably the internal nicad. > > They all need to be replaced at this point. > > -- John. >
