ps Message #4 Posted by Ellis Easley on 12 Apr 2003, 7:24 p.m., in response to message #3 by Ellis Easley
I can get the drive unit out of the 9121 on my own, I just need to know the steps for getting rid of the hardened grease.
BTW, you mention that the 9114B drives have power on the 34 pin data cable - Tandy/Radio Shack used drives like that in the computers built by Tandy at the end and for quite a while before. I don't think Tandy thought it up, I'm sure Sony offered it that way. Both 720K and 1.44M drives like this were used. You can see on the PCB where there are places for optional zero-ohm resistors which either connect all the odd pins (except pin 1) of the data connector to ground or connect one group of odd pins (3,5,7,9,11) to +5V and another group (29,31,33) to +12V (all the remaining odd pins except pin 1 [providing a logic signal] are directly connected to ground). When the drive has the option for power on the data cable, the 4 pin power connector is deleted. Tandy used a data cable that ran to the first FDD first (remember that the standard IBM "twisted" cable has the connector for the first drive at the far end - better for transmission line termination with removable 150 ohm resistors installed on the drive at the end of the cable, but later abandoned, with permanent 1K resistors on all drives, and a shorter cable used), then after that first data connector (or possibly after a second receptacle connector to allow a second 3.5" drive of the same type), there are punches in the ribbon cable to isolate those odd pins on additional devices from the +5V and +12V coming from the motherboard.
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