Thank you everyone for the quick response! When I power up the computer, all pixels are on and remain dark (LCD is entirely "black"). Contrast potentiometer: Seems to work as intended. The display will lighten or darken as the potentiometer is adjusted. LCD PCB: No signs of corrosion and/or damaged traces. ROM: I'll ohm out the traces to see if I can find any broken connections. Otherwise, are there any other troubleshooting steps I can take? RAM: Jeff, great video! Thank you for sharing. The M100 Test Harness sounds like an ideal tool. I have limited experience with a logic analyzer however it looks like a fun challenge. I'll try to duplicate your setup but I may need some tips on how to configure the Saleae software... Eric On Thursday, December 28, 2023 at 08:17:02 AM PST, Josh Malone <josh.mal...@gmail.com> wrote: On Thu, Dec 28, 2023 at 10:35 AM <bir...@soigeneris.com> wrote:
When LCDs with these types of LCD driers first power up they turn on all the pixels. You will see this even in brand new ‘modern’ dot matrix LCD module (on the new LCDs the multiline modules tend to only make the first row black on power up.) Only after the computer sends a rest command to the LCD drivers they will clear the screen. Ah! Okay, I misunderstood that process then. If the driver ICs themselves set every pixel then I agree it sounds like the machine is not running code then. Thanks for clarifying this, Jeff. I appreciate it. -Josh
