AMI Model K Selection System
The AMI Model K was equipped with 3 types of selection systems: Manual, Automatic, and Electric. In the manual system, the human operator was the "brains" of the jukebox, selecting the letter and number with hand wheels, and pushing in a button to "write" the selection into the memory bank by pushing in the memory pin. The Automatic system was similar to most other electro-mechanical jukebox selection systems: the combination of the letter and number buttons pressed created a unique electical circuit to a contact on a circuit board, and the memory pin-setter mechanism rotated until it detected that circuit and then fired a solenoid to set the memory pin.
Our model K has the "Electric" selector system. This provides a serial data link between the keyboard and selector unit. It is the exact same system used by remote wallboxes to communicate with a jukebox...therefore the "Electric" units did not need any other equipment to accommodate wallboxes. The system generates data in the form of pulses for the letters first, then the numbers. For example, if B-2 was selected, there would be 2 pulses generated, then a short pause, then 2 more pulses. This signal is generated by a motor moving wipers on circuit boards at the keyboard according to the letter-number combination pressed.
This signal flows to the pulse receiver, and causes the pulse receiver to pulse a relay twice to set up the "B" contact on a "Letters" circuit board, and then the "Numbers" relay pulses twice to set up a "2" contact. If "A-5" was selected, the "Letters" relay would pulse once and the "Numbers" relay 5 times, and so on. These are double-sided circuit boards. The wipers on the front of the circuit board move according to the pulse relays to set up a circuit between the two, appropriate to the selection. On the back of the circuit board are wipers attached to the memory-pin setter arm shaft. These wipers spin (along with the pin-setter arm) until a circuit path is detected. The arm then stops spinning, and a solenoid fires to push the memory pin in.
There is a TON of moving wiper contacts and circuit board contacts on this system, and all it takes is a little oxidation or a slightly bent contact wiper to completely quit working. Repair on the pulse selection system involved thoroughly cleaning the circuit board contacts with non-flammable Deoxit and then allowing it to dry. Flammable contact cleaners are not recommended here as sparks are generated by the contact wipers which could ignite anything flammable on the circuit boards. We also burnished the wipers with a contact burnishing tool and re-formed bent wipers.
Here is a picture of the AMI mechanism. You can push the mechanism back out of the cabinet to work on it more easily. The pulse receiver unit is located in the middle in the front of the mechanism.
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