db-19 cables from older Mac 400K 3.5" drives

[buggie@argo.unm.edu (stephen e buggie)]

               DB-19 ROUND CABLES FROM OLDER MAC 400k SINGLE-SIDED DRIVES

               THESE CABLES SOMETIMES WORK WITH A2; SOMETIMES NOT: WHY?




	Occasionally, I salvage an older Mac 400K single-sided external
3.5" disk drive at a flea market or yard sale.  This drive is TOTALLY
INCOMPATIBLE with A2, and must not be connected to any Apple II.

	I salvage the chassis screws, the round pancake magnet (makes a
great fridge-magnet), and the round db-19 cable.   The cable is short and
has twin thumb-screws.

	I once did pin-out measurements on this short db-19 cable and
found them to be the same as with Apple II db-19 cables.

	I've connected this short Mac db-19 cable to Apple Disk II drives.
About half the time, the drive works perfectly.  Yet, with half the short
cables, the drive does not work well.   WHY???   My _hunch_ is that
possibly the male pins on the db-19 plug may be slightly thin, and some do
not make good contact with the walls of the female db-19 socket.   

	Any ideas, anyone?????		Steve Buggie     buggie@unm.edu