Ahh now we're getting somewhere!
Good find on the test hooks - I've been there a few times myself. Lots of noise spikes on the analyzer obviously shows noise, but when its the odd spike - especially in sync with other signals, can throw you right off.
So, no IO60/IO120 pulses, to me, sounds like either these devices are indeed dead, or the lines aren't being selected (there isn't a '1' being sent through the shift register selecting each line at a time). I'm fairly sure the 'S' (also called, Scan Startup, or First Line Marker, FLM) is a reset pulse for the common/line drivers. That means this pulse tells those drivers to reset their shift registers so it starts form the top of the display.
You understood correctly
As I understood the HC74 / 40103 are only there to avoid polarisation.
In regards to what makes the drivers display something in the glass are pins LOAD, CP, D0~3 and IO1~160.
Yes, you are correct. However, the S is also required to drive the display. Annoyingly, different manufacturers have different names, but generally
- CP the data load, the clock that loads in D3-D0, so that'll be widthofdisplay/4 clocks per line (in this case 320/4 = 80).
- LOAD (also called LP, CP2 CL2.. ugh) is the line marker, that is used to indicate the start of a new line - a pulse selects the next line down.
- And S/FLM is the reset pulse to start a new frame. Without this pulse, the display won't work.
- yes IO160 are the connects to the glass so are required, but not from, the "user" (who provides the control signals).
The HC74 / 40103 use the LOAD (line) clock to produce the M/antipolarisation signal, but another way of producing the M signal is to use the frame/S signal divided by 2. Some display I have use this, but most use a counter and JK flipflop (40103/74 combo) like this one. So my point is, the S signal, although it is connected to the 40103, it's main purpose is to start the frame for the display, and so
should be connected to U1, pin9. Without this I dont' think the display will display anything.
I'm not suggesting this is definately the problem, I will do a test later today - this post made me hook up my LM32P07 for testing, even though it seems it has different drivers. I will disconnect the S signal, and play with the contrast, if the pixels still go all white, but doesn't do that on yours, then that isn't the problem.
So, in the mean time,
check that S (pin 12 main connector) is connected to U1, pin9, IO1. If not, I would add a jumper there. It can't hurt as its an input pin. I'll post my results later today. Good luck!