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SECTION 3: GENERAL CHANGER OPERATION
Coin Level Sensing
The Pulse-Echo coin level sensing method emits
and detects sound waves. The number of coins
is calculated by the amount of time it takes the
emitted sound wave to defl ect off the coin stack
and return to be detected. (See Figure 17)
Figure 17
Pulse-Echo Coin Sensing Techonology
EMIT
RETURN
Pressing the escrow lever physically opens the
acceptor gate, allowing bent coins and foreign
materials to fall into the coin reject chute. Move-
ment of the front gate is also detected by the coin
changer electronics and is communicated to the
vending machine controller causing any customer
credit to be paid back.
If coins are deposited too closely together (fast
feed), one or more coins may be rejected if the
acceptor cannot safely route them to the appro-
priate coin tube. When any object (coin, counter-
feit coin, etc.) is rejected, the changer will tempo-
rarily delay coin validation to allow the rejected
object to exit the changer.
Housing Module
The Housing Module consists of the changer
housing, MDB harness and changer board. The
backside of the housing has three mounting holes
for attaching the Guardian changer to the vend-
ing machine. The cashbox coin chute is also part
of the housing.
Coin Tube Cassette
The coin cassette contains the six coin tubes that
store coins for change payout. The front and
back halves of the cassette hinge together to
form the coin return chute. Rejected coins from
the acceptor pass through the center of the cas-
sette assembly and fall out the bottom of the coin
changer. Accepted coins are guided into the coin
tubes.
Payout Module
The bottom of the Guardian changer is the Pay-
out Module. Coins stored in the coin tubes of the
cassette are dispensed by the payout modules
motor driven belt. The belt has two pins attached
to it, which engage a sweeper at the bottom of
each coin tube. When the sweeper is engaged,
How often does the changer scan the
tubes?
The Guardian will automatically scan
after any coin deposit or payout. It will
also scan after any “change in state”,
e.g. when the payout cassette or
sorting door is opened then closed.
I added one coin to a tube and the coin
level sensing did not detect it. Why?
The Pulse-Echo coin level sensing
method is accurate to 2 coins. It
may not necessarily detect a difference
when a single coin is added. This
is normal and is within the technology’s
margin of error.
Does the Guardian require tube sensing
calibration as with some other models?
No, it does not require any calibration to
attain its level of accuracy.
