On Wed, 22 Oct 1997, Mzthompson wrote: Uh-oh... I've seen _that_ one before... I have never seen an LK201 with a logic fault. What tends to happen is that a short occurs somewhere in the membrane keyboard assembly which confuses the microcontroller at power-on. To check this : 1) Remove the feet and the 2 screws under them. Lift off the top cover. Unplug the keyboard cable at both ends 2) Release the little clips, slide the keyboard to the right, lift it out of the lower cover 3) Remove the heatsink clip from the 7805. Remove the screw from the LED mounting. Move the logic board away from the keyboard unit. Unplug the 3 keyboard tails 4) Either put pieces of plastic/card under the metal clips that hold the tails in place (to avoid shorting all the pins together) or bend up the tabs and remove said clips altogether. Now plug the bare logic board into a VT220 or similar. You'll probably find that the lights do the right thing. In which case you've got a matrix fault. The bad news is that fixing the matrix is next-to-impossible. You _can_ attempt to dismantle it (cut off the heat-spread pins on the back, remove the keycap mounts and the leaf springs, unfold the membrane). Putting it back together is less easy - there isn't enough of the pegs left to spread over a second time. I managed it once, but it was a _fiddle_. Washing the assembled keyboard (even in an ultrasonic cleaning tank) never worked for me either. There are 2 versions, one (the much more common one in my experience) based on an 8051, the other based on a 6805. I traced out the schematics of the first one years ago, and it took about 30 minutes to do - it's just the 8051, a few 74145's as column decoder/drivers, a line driver and receiver for the terminal interface and the 5V PSU. But, as I said, I've never seen a fault in that section. -tony