Posts: 875
Threads: 37
Joined: Jul 2005
General disassembly instructions are here. More details from memory:
- remove the 6 screws that hold the back of the calculator. Two screws are under the lower two rubber feet. Don't remove the feet, just lift the outside edge of each one to access the screws. Two screws are in the battery compartment. The other two are under the instruction label at the upper right and upper left. Either peel back the label or poke holes in it. When you remove the back, the shorting contact in the battery connector well will be free, make sure you don't lose it.
- remove the 8 screws that hold the main board (called the
spine in Dave's instructions) to the front of the
calculator. No need to remove the small board that has
all the electronics on it. It is connected through a 25
pin connector at the bottom, which is usually just a
friction fit with springy contact fingers, but I have also
seen it soldered (I think).
- with the calculator keyboard-down, lift out the main
board. The keys will be free at this point, so if you
turn over the front half of the case, they will fall out.
- turn the main board over, on the front will be the key
contact strips and the LED display at the top. At the top left right below the display are the ON/OFF switch contact pads. Clean these with the contact cleaner of your choice. The plastic switch slider itself will probably still be sitting in the front case. On the back of the switch slider you will find a springy metal contact. Clean this piece.
- lubricate the above contact that goes under the switch
slider and the contact pads on the main board with a
lubricant of some kind. I believe Radio Shack sells a
silicone contact lubricant that works.
- while you have it open, clean all of the switch contacts
as described here.
Also lots of good information
here.
Good luck, ask if you need more assistance.