When you say
Apollo, there are two totally different sytems to consider.
The early
Apollo scrollers that have a "Q" in the model name or number, were manufactured by Spectrum engineering in Canada, and are the same as
Chroma Q scrollers. If they have the "
dip switch" addressing
system, then they are autocalibrating, and will recalibrate any time that they have too little
voltage to operate. This will happen anytime that too many scrollers are asked to change
gel positions, when there are too many on a powersupply, or the cable lengths are too long.
Of course there is also the possibility of the
voltage regulator is failing in the
power supply and allowing
voltage fluctuations from the mains.
DC
voltage has quite a large
drop over distance, on
wire. That is one of the reasons for the
return line from the last
scroller to the supply. Even with a
return line if the total loop is too long then the cable becomes a large part of the resistance in the
system. When the scrollers are required to move and pull more
current, the cable resistance adds more to the amount of
current required by the supply.
Also if these are of the Q series, they calibrate and measure their position with two electro/optical devices that are triggered by what appears to be a small windmill. If there is too much dust in the
scroller, the electro/optical devices can't see the interuptions of the blades on the windmill.
Most all of these things are suggested in the posts above. If the Scrollers are of the newer
Apollo "Colorsmart" series, then there might be other things to consider.
If you have the ability, connect a DC voltmeter to the
power portion of the cable. Positive is on pin 4 and negative on pin 1. When you give all of the scrollers a command to change colors, if the
voltage drops to 18 volts or less, you need to look at Cable lengths, possibly bad solder connections on
power leads, or too much cable or too many scrollers on a supply. If you have the capability, you could measure each
scroller for
current draw. When they are moving, they should draw approximately 0.6 amps or less. If it is an amp or more, check to see if something is dragging in the
scroller.
Tom Johnson