Continuing from another topic:
Quoted from denoument:
I'm working on a project pin and these roms are helping out a lot. I think the blanking.txt calls out the wrong pins. Instead of "IC7 pin 6" it should be "IC7 pin 8". Instead of "IC12 Pin12" it should be "IC23 pin 12".
What frequency signal should I be getting at IC7 pin 8 with the blanking rom installed? My wavelength is 0.118ms (~847hz). It is on 50% of the time. When I look at IC23 pin 8 the signal is high for 73% of the wave. So it is only draining Q5 for 26% of the cycle. I have two head scratchers as well...when I put my logic probe on the Q5 trigger (IC23 pinthe blanking signal goes high(TP4 goes high)...also if I replace C32 with a smaller capacitor the blanking signal works (TP4 goes high).
I can't get the blanking signal to go high (TP4) with this rom. I am able to pass the leds, displays, cmos, and ram tests no problem. I have a meter, logic probe, and a logic analyzer to work with and from what I can tell pin 8 on IC7 (the Q5 trigger) is pulsing but IC23 pin 12 (the blanking threshold) stays high around 3.6V. I've replaced Q5, C31, C32, and IC23. Basically all the components that relate to the blanking signal.
Quoted from pincoder:
Thanks for the detailed information and positive feedback!
Before I can give you any detailed answers I'll need to know which game and system board are you running this on, and which schematics you are looking at.
To get you started in the right direction, the blanking signal should be showing up on PIA1 (PIA at address 2800) pin PA2 and waits for 3 clock cycles before toggling the pin.
Williams Lucky Seven 1978 Solid State
System 4 board
I am using the Lucky Seven schematics from ipdb.org as well as the Stellar Wars 1979 schematics on ipdb.org, the Lucky Seven schematic is drawn by hand so isn't the cleanest to look at so I'm using the Stellar Wars Schematic as well.
The clock on IC1 pin 37 toggles at 888.9kHz. The clock toggles for 0.3seconds before the PA2 signal starts to toggle. PA2 toggles at 8.949kHz, so one hundred times slower than the clock. PA2 starts about two and a half 8.949kHz cycles (0.3ms) after the RESET signal goes high (IC5 pin 14).