Take voltage measurements at the relevant pins (11 for CAPS LOCK and 12 for SHIFT LOCK, if I read the diagram properly) of IC32. You should see a high-ish reading (up to 5V) when the LED is off, and a lower reading (between 0 and 2V) when the LED is on. (TTL ICs can sink more current than they can source). What are those pins doing when the LEDs go out? Can you make the voltages change by pressing CAPS LOCK / SHIFT LOCK on and off?
Statistics: Posted by julie_m — Mon Feb 24, 2025 12:29 am