The corner of the SYSTEM14 PS board caught my eye as it looked like it has an H11A1 opto-coupler. I happen to have an aircraft PS that had a similar arrangement.
After a little bit of tinkering, I believe both boards share the same design element with respect to synchronization where, if a signal comes in to the opto-coupler, it holds the NE555 timer OFF. Pulling down that signal will cause the first pulse of the double-flash to occur. Pulling the signal back up will cause the second pulse of the double flash to occur, then continue to hold the NE555 OFF.
So I jumpered a signal in from an Arduino board and voila! the Arduino controlled the flash of the aircraft PS.
So if the SYSTEM14's "Master Sequencer" fails, each PS is left to double-flash according to its own NE555 timer (which the brochure describes as "Random").
One thing I don't get is the odd number of heads (9) in the "Secondary" mode. Does the "Master Sequencer" have individual control over each of the two heads within each PS?
In any case, thanks for sharing the SYSTEM14 pics! This is a really intriguing device!
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