[Ham-Mac] Mac Classic II Serial Port Kaput

[Chris Smolinski]

>Well, this is a Ham mailing list. Why not take the first defective MB
>and do some reading. Then graft your own RS-232 driver to the 85C30 in
>place of the AMD 26LS30 and 26LS32 drivers? This isn't rocket science
>and is exactly the kind of easy thing that one might do as a first
>project.

Or if you don't want to cram something into the already tight space 
in the Mac, build an external buffer circuit that translates between 
the RS422 and RS232 levels, which could also add protection.

>If you don't mind (5) 1.0uF capacitors then the MAX-232 is a popular
>choice. One could even route a ribbon cable out the back with DB-9P in
>PC-AT pinout.

The MAX233 is a bit cleaner in that you don't need 4 of the 5 caps, 
since the charge pump caps are built in.