by Rob-NYC »
Wed Aug 10, 2016 1:59 am
Preston (do I remember the name correctly?)
Open the stepper box and look at the Play Control relay. Is it energized?
-if so, something is shorting the scan line that goes into the memory bank to ground. Uncouple the single-conductor link coming from the memory unit. the mech should stop. If it does, then the problem is in the memory unit. this is where most of these sorts of problems occur. "Something" is grounding the metal plate that runs down the inside middle of the memory unit. If you don't want to open the memory unit,, try removing it from the mech and shaking at different angles and see if something falls out. There are a lot of springs and some other small parts that can break off and work their way into causing this problem. Connecting a meter reading continuity from the small connector to the grounding pin on the Jones plug is a good way to speed up the process of finding the culprit.
-Sometimes residual magnetism will be strong enough to hold the Play Control relay down. Tapping on the contact actuator should cause it to pop up (be careful that is 120Ac on the contacts). This is probably not the issue here.
Rob
"If we believe absurdities, we shall commit atrocities" -- Voltaire