I’m not sure I understand your message or where the cap would get a higher voltage? But I imagine I can add a zener to clamp things if needed and maybe a current-limiting resistor? I opened my supercap modded NEC just now and measured the voltage across the cap, while running on battery, at 5.08v. With the NEC powered from the wall, and on, it reads 5.08. Remember, this is just a replacement for the internal memory backup battery. Not the main battery.
After running my Tandy 200 for some time the LCD display is running now with a more even contrast and it seems like the contrast knob doesn’t have full range? When I power the device off, the garbled lines written to the display have deep contrast but the information written to the display under normal operation has very little contrast even after some adjustment with the contrast knob. The display is difficult to read in a well-lit environment. Is the fix a new display or should I be troubleshooting the circuit? If someone had some voltage readings at the LCD ribbon I could check, that would be helpful. I’ve hit the contrast knob with contact cleaner but no change observed. Thank you. - Will Kibler
