IC removal

I decided the easiest way to control the 1920-0092 driver chips would be to desolder the HP 1820-0116 4 bit latch chips. 
Now I can solder wires to the driver chips without interference from any of the original digital logic.
I got all 6 chips removed and did some signal tracing.  I found the GND, +5, and HV pins.
Next I'll hook up the 24 control wires to my 74HC595 chips and then power and ground.
Then I'll be ready for some testing...