Quoted from slochar:Yup did you buy it from Joe s. By any chance? If so you have my old black pyramid and I never could figure out why it did that
This is an issue with the cheap squeak sound board. Exacerbated by MPUs with longer reset widths.
When the cheap squeak comes out of reset it programs the 6803 processor mode. The pins that program the 6803 mode also happen to be solenoid signals and forces the bit pattern for the outhole. The PIA ports are in Z state during reset making it easy for the cheap squeak to drive those signals, even through the series resistors to the solenoid decoder.
There is potential coil melting problem here. If the MPU and Cheap Squeak are below the 5v power monitor level and stuck in reset, the mode programming diodes on the cheap squeak can lock on a coil. If the cheap squeak and mpu had a reset buttons, if you held them both down, the outhole would lock on until the fuse blows or worse.
I fixed this on the replacement cheap squeak I make. I put in series resistors and a buffer chip between the solenoid signals and the 6803 processor. That way the mode programming will not be able to force the solenoid pattern for the outhole while in reset. All other bally sound boards have a buffer chip on the solenoid input signals. I think the "cheap" part left out that circuit and they decided to just live with the potential coil pulse at power on.
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