HP41CX, not working.

[Didier Lachieze]

Hi, when comparing your display picture with the display character structure in the 41C/CV/CX service manual it appears that the segments lit are all segments in row 0 (segments 00, 01, 02, 03, 04 and 05). There are 3 rows and 72 columns signals driven by the display drivers to control the 12 characters (the row signals are common and each character has 6 columns, so for 12 characters this represents 72 columns signals).

So the display drivers state is: row 0 set to on, row 2 & 3 to off, all columns signals to on. But I don't know the root cause. You say that there is no response from the keyboard, so I suppose that even BEEP is not working, which means that the calculator is locked. As you changed the CPU board this locked state may come from the display driver, but it's just a guess.