OK, I had a chance to connect the scope. Careful though: my printer generates no color – one of the 32V lines may be bust. Measure before you connect a logic analyser yourself. Don;t rely on my measurements.
Pin / All black text
1, 2 0V (GND?)
3 0V while idle, const 5V while printing (head electronics power?)
4 0V, const 1.5V while printing (1.5V reference?)
5 0V, 1.5V few long pulses
6 0V, 3.5V, pulses 1us long
7, 8 0V, 30s sine wave around 1.5V (+-0.5V)
9, 10 0V, 1.5V with sine wave disturbances at 60us
11 0V, 3V, slow pulses
12 0V, 3V, pulses around 10us
13 0V, 3V, pulses around 100s
14 0V, 3V, clocks at 3us
15 0V, 3V, pulses between 10ns and 1us
16, 17 0V, 1.5V +-0.5V pulsed, sine wave (noise?)
18, 19, 20, 22 0V (GND?)
21, 23, 24 2V, 32V const while printing
Any suggestions welcome. I will try to hook up the logic analyst soon.