|Cardreader repair; some instructions|
Message #4 Posted by Andrés C. Rodríguez on 12 May 2000, 10:41 p.m.,
in response to message #3 by Erwin
There are 4 little screws that you can see on the "inner" side of the card reader (the side that mates with the calculator). These tread on small metal "bridges" that connect the upper and lower part of the case. You will not see the "bridges" until the case is open. There also is a large screw behind the product identification label on the lower side.
After separating the two halves of the case, you will find two screws that hold the card drive in place. Carefully remove the five colored cables that connect the magnetic head from the printed circuit in the back (In my unit, the color order from top to bottom is RYBOK: Red Yellow Blue Orange Black), and two cables, red and black that go from the lower printed circuit board to the motor. Record the polarity for reassembly.
The cables are connected using friction sockets, remove them by pulling gently with a hemostat plier. In my unit, after two or three removals and insertions, the sockets were somewhat loose, so I soldered the cables in place. I hope you may avoid the loosening of the sockets.
You will then need to remove three screws that hold a small printed circuit board, and finally two more screws, to separate the upper and lower part of the plastic track that the card runs in. (I am describing this from memory, I hope I am not missing anything important)
There are some small plastic pieces and also metal leafs: two of these act as part of switches that detect the card presence, and a third provides a spring action on a side of the card track, to help keep the card aligned. Be very careful with this pieces, not to lose, damage or misplace them when reassembling the card reader. I suggest to take notes or to take digital photographs at each step.
The capstan is locked with a pin that seems to be a screw, but it is not, it is to be removed pulling gently. Clean the reminders of the old capstan, and substitute with two small rubber o-rings (about 6mm outside diameter, 3 mm inside diameter) At least on my case, airmodel fuel tubing was not adequate, o-rings worked the first time.
Reassemble everything in reverse order (easier said than done). Put special care on the position of a photoemitter and detector pair that sense the card presence, and... it should work!
This is an improviso writing, I suggest visiting the links mentioned on my previous message, for more detailed information.
Again, good luck! (and be very careful!!)
PS: the "grease" is the remnant of the original rubber, it fools everyone into thinking is kind of a lubricant.