AMS 39-640 Will not accept money- "Service Change" Displayed

[nightshift]

My previously working (for over a year) AMS 39 will not accept any money. The refrigeration unit has been removed so it's just a snack machine. It takes dollar bills then refunds four quarters. When depositing four quarters it registers the four quarters credit, then refunds them. When opening the machine and pressing the service mode button it displays "0 errors" then displays "service change". I swapped the coin mechanism with a unit from another machine and the same things happens. I filled all the coin tubes to the top. I believe this coin mechanism is workable but will swap it for another if that's recommended. Maybe both are fried? Any help is appreciated. I'm fairly new to vending and would like to troubleshoot this without calling a repairman. Thanks, Ted. c#949 466-1085

[AngryChris]

Did you check the prices?  It doesn't sound like it lost its pricing but it could have.  Also, you may have to perform a tube fill.  If the machine is keeping track of the coin level instead of that coin mech, and you've been refillinh it manually, it could think it's low on change, particularly nickels and dimes.  If so, it will let you purchase with nickels and dimes.

[nightshift]

Thank you for the suggestions. I will check both these tomorrow.

[Vendo Mike]

It sounds to me like it's immediately making change from bills being inserted.  If this is the case, you might check to make sure the coin return linkage is not resting on the return lever on the mech. 

[nightshift]

I checked both suggestions and no change. I did go into the service mode and check the tube fill: it was on. Both nickles and dimes are also full. I also checked the prices. They are still listed correctly when a selection is input. While in the service mode scrolling through I increased some prices and they were retained correctly. At one point the machine came back online and I was able to buy items without issue. I opened the door back up to refill a few things and the problem returned. I then thought the door switch was still open which was causing my issue. I taped the door switch in and closed the door. Problem still there. Whatever I did (scrolling through service mode, changing prices and opening/closing the door) fixed my problem but by opening the door again I'm back to square one. Could the door switch be bad even with it being taped flat which would keep the circuit closed? Maybe I should replace the door switch to rule this out? I don't have one but this would still be cheaper than a repair call.

[AngryChris]

If it was a bad door switch, I'd expect you to see something else on the display to indicate that the door is open, such as error/check messages in service mode.  I wonder if you have a bad harness or something is pushing on the coin return when you close the door.  Make sure no harnessing is getting squeezed when you close the door.

[nightshift]

Problem solved. I had to bring a repairman out but he was close and didn't charge for a full service call. Turns out the optic drop sensor was loose and a bit dirty. He tightened two screws on the left side and wiped down the glass on the right side. We also checked the connections on the sensor and the lead to the main board. He also showed me how to scroll through the menu to check if any errors are displayed for the sensor too. Since I have two other AMS 39's the lesson was very helpful. Thanks for everybody's suggestions.

[AZVendor]

Bargain!  No discounts from me no matter how close I was.