Technical Support Document 040 - 12/95

REPLACING ANALOG MULTIPLEXER CHIPS IN STARLITE 55 COLORHEAD MOTHERBOARD

The computer in the Starlite 55 Colorhead monitors many different input voltage signals from it's various sub-systems. These signals include the voltages from the color sensor that represent the amounts of Red, Green, and Blue light present in the filtration coming from the Starlite's diffuser. Other voltages represent the Density Probe reading, the Voltage being applied to the lamps, and other internal signals.

To monitor all of these signals, the Starlite's computer uses a Analog-to-Digital converter. This is a device that translates voltages into numeric values that the computer can understand. The computer can only read one voltage at a time, so it needs a means of selecting which voltage to read at any given time.

This is done with two Analog Multiplexer chips, located on the lower left corner of the Starlite's main Motherboard. These chip basically act like selector switches, which the computer can control electronically.

Sometimes, these chip will suffer damage, for various reasons, and as a result, they will not correctly convey one or more of the voltages to the computer, causing various different problems in the operation of the Starlite.

To replace these chips, please follow the steps below:

1. Turn the power to the Starlite off at the main switch, and open the door.
2. Remove the Mixing Chamber and filter transport to get a full view of the Motherboard.
3. See the figure at right to locate the two Multiplexer (MUX) chips.
4. Remove the chips using the tool provided. To do this, place the hooked ends of the tool at either end of the chip, and gently "rock" it while pulling it out of it's socket. Note that each chip had a small notch in one end. Each socket also has a similar notch. These notches must be aligned (at the same end) when the new ones are installed.
5. Insert the new chips, making sure that the notches are at the same end (the left-hand end) as the notches in the sockets. It is easiest to position one row of pins into the socket first, then lower the pins of other side into the socket. When all pins are positioned in the socket holes, press the chip gently but firmly into place. Make sure that it is fully seated.
6. Double-check that the chips are properly seated, with their notches pointing to the left (the same end as the notches in the sockets), and that all pins are inserted into the socket holes.
7. Once you are sure that the chips are properly installed, re-assemble the Starlite.
8. Turn the power on in the normal manner, and check that the machine operates properly.

NOTE: When these chips fail they may have caused some internal settings in the Starlite's computer to be adversely affected. If the Starlite does not function properly, please perform an Auto-Calibrate Color Sensor routine. This item is found in the STARLITE DIAGNOSTICS MENU, item #7.

If you continue to experience problems, please contact your dealer or ZBE.