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Royal 660 drop sensor adjustment


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I have a 660 Royal GIII that I get occasional complaints about taking money with no vend. Every time I check it out it's working fine. This isn't the type of place I'd expect them to lie about it so I'd like to calibrate the drop sensor just in case. The manual seems easy enough to understand how to reset the adjustment screw on the board but I can't find it or the LED light it mentions in the manual. Is anyone familiar with it or can take a photo of theirs to point it out on their board? I don't know if it's just my old eyes or what.

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Follow both of your grey harnesses up to the logic board.  One is for the temp sensor, if you have one, and the other is for the drop sensor.  Next to this connector you'll find a small potentiometer with a tiny flat slot in the brass adjusting screw.  This is the adjustment.  The screw might face toward the right but should be facing outward from whatever edge of the board the potentiometer is located on.  Next to the pot is the LED that will be virtually invisible until if flashes.  Any tapping of the delivery chute will light it up.  

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It can happen!


My Royal 660 was doing same thing until I back off on setting, it was to sensitive!


I was getting complaints also!


Now customers are happy, and I'm not scratching head!


;D  ;D  ;D 



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Will a Vendo 821 do this as well?  I occasionally get calls from one of our hospitals that the machine dropped two bottles and now shows sold out.  It is always in column number 1 and number 2 that do it, most frequently in column 1.

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Verify that your package setting in the rotor is set for large package and then set the drop sensor to the factory default shown in the manual. If it drops more than one item then adjust the sensor setting by one number more sensitive and test. Don't forget to test other columns as well to ensure you don't create more issues. Particularly test the end and center columns.

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It's weird, column 1, 2, and 3 run 24oz pepsi.  The problems always occur with these packages and not the smaller coke bottles.  If it were not sensitive enough, wouldn't it be more likely to do it with a smaller package size?

Also, I can't find any way to adjust the sensitivity of the drop sensor in the manual.  What is the process to do that?

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Make sure the depth setting in the programming is correctly set to 1 (dSEt).  I was wrong about there being a drop sensor adjustment - there isn't. 


If your machine is a Trade (generic) machine or a Coke or HV3 model then you have one drop sensor.  If you have a Pepsi HVV model then you have a dual drop sensor.


Multiple vending without cancelling a credit is a cut sensor harness or bad sensor and if it happens to all columns you'll need a new sensor.  In that case the machine will allow 4 vends before it stops and shows "sold out."  If your problem is only on the two or three columns then check the depth setting on the can clip on the column partition by following the setting on the door label.  Also try moving these selections to your middle columns where they'll have more room to drop.  If this problem persists then you could still have a bad sensor.  If the sensor LED (on the board) is constantly on then you need to replace the sensor but first unplug the sensor from the board.  If the LED still stays on then you need to replace the board. 


I don't think you have a global problem as it sounds like it's just with the 24 oz bottles, so it's probably a physical setup issue that might be fixed by moving the products to middle columns.


Are you getting any dry vends or empty vends that cancel the credits?

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Here is the most recent adjustment procedure. Royal changed the vend sensor a few years ago to one that is much more reliable.



ADJUSTMENT: Located near the control board’s chute
sensor connector at position R126 is the sensor adjustment
trimpot, which includes an adjustment screw. The trimpot
is used to adjust and fine tune the sensor. It is capable of
turning both clockwise and counterclockwise. Located
adjacent to the trimpot is the sensor adjustment LED
indicator light. The indicator light is mainly used to aid in
adjusting the sensor but can also be used to test its operation
during product impact.
1. Turn the adjustment screw clockwise until the indicator
light comes on.
2. Turn the screw counterclockwise until the light just
goes out.
3. Continue to turn the screw counterclockwise one (1)
full turn. Note: Slight adjustments may be needed
outside the factory set one turn. Turning the adjustment
screw clockwise makes the sensor more sensitive and
counterclockwise makes it less sensitive. Test vend after
every 1/4 turn.
For multiple vending from all columns, make sure the
sensor is adjusted to the factory specifications as listed
above. Next, turn the adjustment screw clockwise 1/4 turn
to increase sensitivity. Test vend columns 1 and 4, and
watch light on the board for a good on and off flash. If still
multiple vending, turn the adjustment screw an additional
1/4 turn clockwise until proper adjustment is made.
For dry vending (cancelled credit with no product delivery)
from all columns, make sure the sensor is adjusted to
the factory specifications as listed above. Next, turn
the adjustment screw counterclockwise 1/4 turn to
decrease sensitivity. Test vend all columns. If still dry
vending, turn the adjustment screw an additional 1/4 turn
counterclockwise until proper adjustment is made.
Note: The minimum recommended setting for the chute
sensor is 1/4 turn counterclockwise from the indicator light.
The maximum setting is two (2) turns. If the sensor requires
a setting outside the recommended 1/4 - 2 turn range, the
sensor should be replaced.

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