Popeye game uses three separate color circuits: text, background, and objects (anything that moves). The text and background graphics contain all three colors. However, the moving objects are missing the red.
The red video for objects comes from IC 3U (74HC175). There is video at the inputs to IC 3U, but the clock signal is a series of very short pulses and it does not change as the display objects move. Consequently, there is no output from 3U going to IC 5A (MB7052) to create the red object video.
The clock pulse comes from the ROHVCK signal on the CPU board and it is developed from the notAI, notBI, and notHBD signals. The notAI and notBI are squarewaves of 2.5MHz and 1.25MHz, respectively. The notHBD is a series of narrow negative pulses at about 15.75kHz.
Questions:
1. Can anyone verify what these signals should be?
2. Has anyone seen, and repaired this problem? If so, am I on the right track?
The RAM and ROM self test is OK, and I have pulled all socketed chips and cleaned the pins, as well as the edge connectors. The +5 supply is good and everything but the red for the moving objects is working fine.
Thanks,
Richard
The red video for objects comes from IC 3U (74HC175). There is video at the inputs to IC 3U, but the clock signal is a series of very short pulses and it does not change as the display objects move. Consequently, there is no output from 3U going to IC 5A (MB7052) to create the red object video.
The clock pulse comes from the ROHVCK signal on the CPU board and it is developed from the notAI, notBI, and notHBD signals. The notAI and notBI are squarewaves of 2.5MHz and 1.25MHz, respectively. The notHBD is a series of narrow negative pulses at about 15.75kHz.
Questions:
1. Can anyone verify what these signals should be?
2. Has anyone seen, and repaired this problem? If so, am I on the right track?
The RAM and ROM self test is OK, and I have pulled all socketed chips and cleaned the pins, as well as the edge connectors. The +5 supply is good and everything but the red for the moving objects is working fine.
Thanks,
Richard