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  • Author Author: Jan Cumps
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Repairing a Vendo V-80 cola dispencer of the 1950s

Jan Cumps

One of my friends has bought a soft drink bottle cooler as a present for his partner.

The outside of the machine is agreeable, but the state of the electr(on)ics is bad. More than 20 wires have been cut off by previous owners and restorers. The only part that still works is the refrigerator.

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At this moment I'm assessing the damage done by previous repairs, and building a plan to make the cooler dispense bottles in some way.

 

My current assessment:

- the motor that activates the vending cycle is toast. So is the gear box of that motor.

- the coin validation mechanism is incomplete and doesn't work anymore.

- everywhere I look wires are cut and bodged together in a seemingly random way. Someone had a go at it, but I think that person was not restricted by any relevant knowledge image

 

I'm planning to decipher the circuit (I purchased a service manual on-line), get the basic mechanism working again, and replace the coin detector by  an optical interrupter.


I'm on a deadline. The cooler is for the girlfriend's birthday. And I'm invited late to the party. My design decisions will be guided by time and 'having the parts available at home' more than efficient solutions.

  • It's great to see old classics being restored. Good work!

  • As a wrap up for my work, a few thoughts on why I went for this particular solution, and a capture of coin detect test and final test with motor and bottles.

     

    I could have taken a number of other approaches. A microcontroller is not needed for this kind of functionality. But I have been working with constraints.

    We did not know what was all defect. We knew coin detection did not work, and that the whole machine with bypassed coin detector didn't work either. A µC gave me more flexibility to also solve issues with other detectors and actuators.

    Time: It was a present from someone to someone for her birthday. I focused on things that I had lying around. All components are second hand (Arduino, power adapter, relais, protoboard, caps) or recovery (IR opto-coupler, led's, resistors, semiconductors and trimpot).

     

    video: review the coin handler

     

    I don't know that making a dedicated circuit would have been more economical for a one-off like this. That doesn't mean a lot though if you compare it to the price of the motor revision.

    image

    We achieved our main goal. The vending machine is ready in time. We'll be packing it and hide it in the garage. The lucky one will get an envelope with a single coin without explanation, and we'll walk her to the garage with that. She can then buy the first botle.

     

    Us celebrating the working machine:

     

     

    Hooray!

  • The machine is back to functional.During the time that the motor was under revision, I've built in the coin detector. Also the re-wiring of the circuit has been reviewed and fixed where needed.

     

    image

     

    image

     

    The motor is now back (the costs to rewind the coils and have the gear box fixed are significant). And we have done successful tests.

    In the video below, taken at the time I was reviewing the machine's state, you don't see all of that yet. It's covering the review of what's wrong.

     

  • in reply to Jan Cumps

    Jan -

     

    If you're willing to blog about the project, we'll be happy to look at supplying you the parts.  The "Internet of Cola" isn't a bad title (thanks Peter!)

     

    Best Regards, Christian

  • Yeah, there is a whole series of mods that can be hacked into the machine. First I could replace the mechanical switches with sensors (optical or magnetic), the cooling thermostat and motor controls are other candidates for modification.

    I can't use the current actuators for low voltage though. The state of the contacts and the amount of bounce is dazzling. It works to activate the 110 V relais, but no chance to get a decent 3.3 or 5V signal.

     

    Some action photos:

    measuring the motor circuit:

    image

     

    coin detector

     

    image

     

    detector proto

     

    image

     

     

    Some hardware:

     

       imageimage

     

    imageimageimage

     

    my proto code

     

    /*
// vento V-80 controls
// no copyright jc 2014
 */

// the actuator relais that will engage when coin is detected
#define RELAIS 8 
// the analog input signal from IR detection circuit
#define IR 0
// how long is the relais actuated when coin detected
#define PULSE_WIDTH 750
// at this level (from 0 to 1023) we consider the IR channel interrupted
#define THREASHOLD 450
// status led
#define RELAIS_STATUS_LED 12
#define IR_STATUS_LED 10




// the setup function runs once when you press reset or power the board
void setup() {
  // initialize the relais pin, so thzt it always assumes not-engaged status at startup and reset
  pinMode(RELAIS, OUTPUT);
  digitalWrite(RELAIS, LOW);
  // mark the infrared detection pin as input input
  pinMode(IR, INPUT);
  // mark the status led as output
  pinMode(RELAIS_STATUS_LED, OUTPUT);
  digitalWrite(RELAIS_STATUS_LED, LOW);
  pinMode(IR_STATUS_LED, OUTPUT);
  digitalWrite(IR_STATUS_LED, LOW);
  
  
  // debug settings
  Serial.begin(9600);
}


// the loop function runs over and over again forever
void loop() {
  
  // when a coin is detected, we actuate the relais for the time defined by THREASHOLD
  if (detectCoin()) {
    digitalWrite(RELAIS, HIGH);
    digitalWrite(IR_STATUS_LED, HIGH);
    digitalWrite(RELAIS_STATUS_LED, HIGH);
    delay(50); // pulse the coin detect led for a moment
    digitalWrite(IR_STATUS_LED, LOW);
    
    delay(PULSE_WIDTH - 50); // keep the relais engaged for the THREASHOLD time, minus the time that we've spent on flashing thr coin led
    digitalWrite(RELAIS, LOW);
    digitalWrite(RELAIS_STATUS_LED, LOW);
  }

}




/* 
  return TRUE when we detect that the IR channel in disturbed (i.e.: a coin is passing through it)
  That is the case when the voltage presented on analog pin IR drops below THREASHOLD.
*/  
  
bool detectCoin() {
  // measure the voltage of the IR circuit
  int iSensorValue = analogRead(IR);
  
  // debug info
  char output[80];
  sprintf(output, "Sensor: %d\n", iSensorValue);  
  Serial.print(output); 

  // if the detected voltage is below THREASHOLD, a coin is passing through the channel  
  return (iSensorValue < THREASHOLD); // there is something in the IR path
}