Wayne Dresser Vista 1 Series, Service Manual

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February 1997 Part No. 920160 Rev A
3.4. COMPUTER ASSEMBLY
The computer is a complete self-contained unit with a built in power supply and memory
retention device
,
see Figure 3-1. It is responsible for performing the following functions:
• Provides 5 VDC to, and monitors the return from, the handle switches.
• Monitors the two output lines from each pulser.
• Converts the data received from the pulsers into a volume amount.
• Calculates the sale dollar amount based on the selected unit price.
• Controls the solenoid drive board to switch on the correct submersible pump relays
and solenoid valves. It also switches the pulser select lines to enable the correct
pulser(s) by controlling the solenoid drive board.
• Maintains electronic product totals.
• Sends sale and product totals data to the control system via a two wire data loop.
• Monitors all dispenser functions, and when a problem is found, generates and stores
error codes.
The Duplex Computers is fused to protect itself from overvoltages and shorts. There are
two fuses on the computer:
• F1 fuses the input to the 5 VDC regulator on the computer board. If this fuse opens
the dispenser will look like it has been powered down.
• F3 fuses the main AC input to the computer; all power to the computer, solenoid
drive board, and the displays passes through the F3 fuse. If this fuse opens the
dispenser will look as if it has been powered down.
Note: F1 is a pico fuse. It physically looks very similar to a small resistor and is mounted
in a socket.
F3 is the more visible glass enclosed type fuse, however, it is insulated with heat shrink
tubing as required by UL.
On the Duplex II Computer there are two option jumpers which are be configured for
proper operation. These are labeled JP2 and JP3. A jumper is on the two pins closest to the
edge of the board on each connector for blending and single hose MGD applications.)
In addition to the jumper settings, there are programming options which must be set in order
for the Duplex II Computer to operate correctly. For programming information refer to the
manual:
“Duplex II Computer Option Programming for 1/Vista Model Dispensers”, part
number 920205.