Diagnosing issues for the first time

[Firebreak]

Hello everyone, first post so let me know if I got anything wrong!

With that being said, I have a vendo 312 and going from top to bottom trying to diagnose all of the issues to get it going again. I have a working coin mech and can put in the correct coin amount and upon pressing buttons get a red light for all of the soda options despite all sections being filled. I have tested the motors with a multimeter continuity test and all come back just fine so I don't believe the motors are dead. There is a small electronic piece called the vend relay from what I can find. How do I go about testing this component to verify it is good? 

Otherwise, how would I go about testing the machine for what parts could be faulty or if there is something I need to reset?

As a side note, is there a good place I can get a wire harness as my harness and some of the connectors are definitely showing their age and exposure to the lights so having one on hand I feel would be smart.

[AZVendor]

You're best bet is to junk that old machine.  It's a lowering shelf machine which is a bad design now that it's 30 or 40 years old.  There are no parts for it.  I'm actually going to say maybe 35 years old since it doesn't have the inverted cabinet bottom that the condensing unit sits in. Regardless, your relay is very unlikely to be the issue as they generally don't fail.  If the coin mech accepts coins up to the vend price you have set and then rejects further coins AND you then hear the vend relay click, then it has set a credit.  Then if no products will vend you have a motor switch issue.  Either a bad motor switch has created an open vend circuit or one or more motors is not home.  The black plastic lever at each motor switch must be pressing on the switch plunger when a motor is home. The bump on the motor cam will press on the lever which will push the switch plunger in. 

To manually vend a motor all you do is pull the black lever away from the switch which will run the motor one cycle to the next cam bump if you release the lever. If all motors test like this and stop turning when they get to the next bump then you have a wiring issue. In that case make sure all connectors are fully on each switch. After that, you're on your own.

[Firebreak]

5 hours ago, AZVendor said:

You're best bet is to junk that old machine.  It's a lowering shelf machine which is a bad design now that it's 30 or 40 years old.  There are no parts for it.  I'm actually going to say maybe 35 years old since it doesn't have the inverted cabinet bottom that the condensing unit sits in. Regardless, your relay is very unlikely to be the issue as they generally don't fail.  If the coin mech accepts coins up to the vend price you have set and then rejects further coins AND you then hear the vend relay click, then it has set a credit.  Then if no products will vend you have a motor switch issue.  Either a bad motor switch has created an open vend circuit or one or more motors is not home.  The black plastic lever at each motor switch must be pressing on the switch plunger when a motor is home. The bump on the motor cam will press on the lever which will push the switch plunger in. 

To manually vend a motor all you do is pull the black lever away from the switch which will run the motor one cycle to the next cam bump if you release the lever. If all motors test like this and stop turning when they get to the next bump then you have a wiring issue. In that case make sure all connectors are fully on each switch. After that, you're on your own.

I will say that I haven't heard a click from the relay, how loud should it be when it activates because the only sound I hear is me pressing the button on the front of the machine. I will listen for this the next time I am there.

Along with this, I understand it is a 40 y/o machine basically but I just am using it as a starting point. With that said, if it is not a relay issue and it is a wiring issue where is my best chance to either find a wiring harness or how feasible is it to create my own? In theory, I have a 3d printer and plenty of tools for electrical work. I would hope to just buy a whole harness but worse comes to worse I could, in theory, make a new one. At least in my mind...

Edited April 19, 2023 by Firebreak
misspelling

[AZVendor]

There won't be any harnesses anywhere.  You'll have to make your own.  Does the coin mech reject all coins over the vend price?  If so then the vend relay is working.  If the coin mech takes coins endlessly then it might be a bad relay but it's unlikely.  Check for loose wires on the relay and coin mech sockets (with the machine unplugged.)  If a wire pulls out then reseat it.

[Firebreak]

12 minutes ago, AZVendor said:

There won't be any harnesses anywhere.  You'll have to make your own.  Does the coin mech reject all coins over the vend price?  If so then the vend relay is working.  If the coin mech takes coins endlessly then it might be a bad relay but it's unlikely.  Check for loose wires on the relay and coin mech sockets (with the machine unplugged.)  If a wire pulls out then reseat it.

The coin mech only accepts coins up to the assigned price. I assumed that the mech would have the logic for that, not the relay. With that said, I will attempt what you mentioned with the motors and motor switches. 

Other than a continuity test should I be testing the motors in some other way or is a continuity test enough? Finally is there a good method to test the motor switch if the motor is not working?

[AZVendor]

Continuity is moot on the motor if it will run manually.  The best way to test the motor swtiches is to replace them since they are relatively cheap.  Or at least get two new ones and then move them down the line to rule out each set of switches.  The coin mech will accept coins until the vend relay tells it to stop.  That is supposed to take place when the credit is met but if the vend circuit is open the relay can't set a credit.  Since the mech stops accepting at the vend price then I would think the relay is good.  I always had these parts on my service truck so I could easily try each thing to rule them out.

Edited April 19, 2023 by AZVendor

[Firebreak]

Understood. Would you happen to have any ideas as to why all of them would show the red light when pressing the buttons despite all of the sections being full?

[AZVendor]

An open vend circuit will disable all selections.  This would only be when a credit is set and nothing can vend.  Do all the lights come on at the same time?  I zoomed in on your photo and it looks like none of the motors are at home.  If this was the first time you loaded the machine then you jammed the columns.  You'll need to empty each column and then set two cans on the upper most lowering shelf and then stagger your cans from there.

Edited April 19, 2023 by AZVendor

[Firebreak]

A light only comes on when I press a button to vend the light for that specific selection comes on until I release it.

[AZVendor]

Check my edited message.

[Firebreak]

Just to verify, home is where the switch is being pushed against by the bumps on the cam? I have attached a closer view below I assumed the opposite where it would be in the home position just after each bump on the cam.

[AZVendor]

The bumps push the black lever against the switch plunger. That is home. I think you loaded it wrong and jammed your columns.

[Firebreak]

Got it! So if I have empty columns the motors should be moving due to the position that the cams are currently or will that only happen if there are enough cans in the column? 

If they don't run when the motor switch is not depressed it could mean that either the motor or the switch is bad perhaps?

[AZVendor]

There are 2 switches on each motor. The one you activate is the motor start switch and the one behind it is the motor carry switch. I think you can manually run it when it's empty. If they won't run when empty then add cans as I described to satisfy the sold out paddle and manually vend it.

[Firebreak]

Ok, so i just had time to test it and the relay is fine, it stops accepting after the dollar amount but none of the motors work from moving either black lever individually or both together away from the switch. With that being said, i did take a multimeter to the prongs on the motor. When moving the black carrier switch it is is at 120v when moving the switch as you mentioned. Could that mean that every motor is dead if they all show 120 and not moving?

[AZVendor]

So you have power to the motors but none of them turn?  You should at least hear a hum from the motor if it gets power. Hold down the sold out paddle for that motor while you test it and see if that helps.

[Firebreak]

Still nothing, and if there is a hum then it is quieter than the compressor running

[AZVendor]

Then unplug the compressor and listen to them.  It kind of sounds like you don't really have power to the motors so you'll need to look closely at the wiring harness from the motors into the door.  If you don't find anything then I would just junk the machine and be done with it.  From the looks of it there has been a problem with the compressor freezing all the products and exploded soda went everywhere.  That can lead to tons of problems.