Once a card is fed from the hopper into the card reader, it sits in the pre-read station until a solenoid presses a pinch roller onto the card to push it into the read station. The read station senses the holes in each card column as the card moves through it, driven by a roller pair pinching the card. The card is then moved up a curve into the stacker, where it will be ejected, then fall down to join the other cards already in the stacker.
I fed one card from the hopper and encountered resistance. From this I looked for and cleared out some crud in the path so that the card can enter properly and come to a stop in the pre-read station.
I then depressed the solenoid lever to start feeding the card into the read station, but it wouldn't move through the station. Testing with an edge of a card showed me blockage inside the throat of the read station.
 |
| Read station, card moves through from left to right |
The read station consists of a lamp at the top, twelve fiber optic cables which feed the light uniformly to the twelve row positions of a punched card. Underneath there are twelve photocells which detect the light when there is a hole in the card at the current column, otherwise they are left in the dark. I found some rodent paste (urine, dust and feces) that was built up over the top five rows of the photocells.
 |
| Photocells |
 |
| Light guides and roller |
Once that was cleared up, I started a card moving from pre-read through the read station but it was jamming at one side in the curved guide just after the read station. Opening up the guide, I found some crud along the edge of the path. It was cleaned out and finally the card could move all the way from pre-read, through the read station, through the curved guide, and up into the stacker.
 |
| Location of the gunk |
 |
| Arc redirecting cards upwards into stacker |
 |
| Inside stacker from left side |
STACKER CORROSION KEEPS SLIDE FROM MOVING SMOOTHLY
The stacker is where cards are stored after they have been read. The card is accelerated out of the reader in an upward arc into the stacker, where the front edge of the card strikes a rubber bumper on the top causing the card to stop and fall downwards.
Jogglers move back and forth at the bottom of the stacker, moving the card that just fell to the left of the machine so that it is up against previously read cards. A metal support on the left is what the cards are stacked against.
As the number of cards in the stacker grows, the metal support moves leftward. It is on a slider that moves along a rod under the stacker, with spring pressure pulling the slider to the right so that it only moves leftwards as cards join the group in the stacker.
The slider has a linear ball bearing on it that moves over a steel rod. The rodent urine and other contaminants have pitted the surface of the steel rod and frozen the ball bearings. The slider will not move freely nor reliably be pulled to the right by the spring.
I tried to smooth down the rod but the bearing itself is shot. I now have to replace the slider bearing and perhaps the rod as well. The rod fits into holes on the right and left sides of the stacker, with a groove on the rod capturing a C clip to keep the rod in place.
 |
| Slider on left, bearing removed and on the right |
 |
| Groove on the rod |
The top of the slider is held down by metal plates running horizontally across the stacker. The top of the slider and the underside of the plates also has some corrosion but I believe that can be resolved.
No comments:
Post a Comment