Snack - Based Troubleshooting and Repair Guide
1670065 Page 6 of 54 September, 2002
a. 120 vac is tapped from the output of the EMI Filter and is input at pins 1 and 2 of con-
nector J25. On the board, this ac voltage goes through the series of diodes D1-D4 (full
wave rectifier), and is output as 120 volts dc at pins 3 and 4 of J25.
CAUTION:
Low input voltage at pins 1 and 2 will invariably equate to low output voltage at
pins 3 and 4. This may cause erratic operation of coin mechanism. Jackpotting
may result as well as potential damage to main controller board.
b. The 0.1 microfarad capacitor functions as a noise filter for the incoming ac voltage
before it is rectified.
c. In line with the incoming ac voltage is a resistor and 1 AGC fuse combination for rec-
tifier protection. The 5-watt ceramic wire wound resistor acts to limit current and
allow the fuse to blow before damage is done to the bridge rectifier.
d. Variable resistor VR1 filters noise from the newly rectified dc voltage. DC filtering is
necessary to provide the cleanest possible voltage for coin mechanism operation.
C. Main Controller
1. The main controller processes all information, data, and decision-making functions for the
entire merchandiser. The main controller is connected directly or indirectly to every major
component within the merchandiser, receiving and processing a variety of inputs and initi-
ating several outputs and functions.
a. These functions are accomplished primarily by way of microprocessor U1 working in
conjunction with the other onboard processor chips. Conditions are constantly moni-
tored with the help of several peripheral devices working in conjunction with one
another. Diagnostic messages are generated and displayed when conditions within the
merchandiser warrant.
b. All machine setup data that must be stored on power down (timers, data processing -
sales, vends etc.) reside in the RAM (random access memory) or Dallas chip. The Dal-
las chip is located on chip base U3 on the board and is located next to, and slightly
higher than the Eraseable programmable read only memory (EPROM) chip.
c. EPROM U4 is usually marked with a version number denoting the features and
upgrades available on the chip. The EPROM is known as the “personality” chip. This
gives the machine its own unique identity, causing a snack machine to operate as a
snack machine, a coffee as a coffee etc. Generally the functions located in the product
configure mode are resident on the EPROM.
NOTE:
Updated versions of software may be obtained from the Parts Department at
1-800-621-7278.
d. Two light emitting diodes (LED) are used. When lit, LED 1 indicates electrical power
is applied to the controller. When flashing, LED 2 indicates that the controller is active
and the software (EPROM) is operating.
2. The connector configuration for the main controller board is as follows:
a. J30 Data Transfer Port. Transfer of data between the main controller and the Inter-
face Boards is performed at this connector. This is accomplished by way of a 16-con-
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