How to expand the C16-memory from 16k to 64k
Warning: You should know what you do! You should know more than the
end where the solder-iron is hot! I give no warranties for this instruction
and your work!
Ok, let us beginRemove all cables from the C16, open the case and removethe board from the case.
Remove now the CPU (U2: 8501) and the TED (U1: 8360).
You must remove the old RAM-chips (U5 and U6: 4416). The best way is to cut all pins and resolder each.
Now you must clean the vias. I use a resolder-tool (pump) for this. I fix the board horizontal, heat the via from one side with the solder-iron and suck the tin from the other side.
After this take two DIL-sockets 18-pins and solder it in the empty places. Don't use the cheapest version of this sockets! Note the mark on the socket and at the board for the right direction.
Now you must cut two wires. One is located on the component side directly
under a chip. This is a little bit difficulty, but with a small screwdriver
you can do it. Look under U7 (LS257). There is a wire from pin 16 to pin
2. Cut it directly in the near to pin 16. You can use a universal mesurement
with resistor-check to check your work.
Now you must use 2 small wires to connect A14- and A15-adress-signal
with U7 and U8 (LS257). Connect pin 26 of U16 (PLA) with pin 2 of U7 (LS257)
at the back-side with one wire. Connect pin 7 of U16 (PLA)
Now plug the new RAM-chips xx464 (64k*4) in the DIL-sockets. Note the
mark at the socket and the chip!
Instruction 1999 by solder/synergy