The wiring
harness is made by Tandy, in the Tandy 6000. That this
harness has power going to a drive power plug that isn't used it typical
of Tandy's shortcuts. They banked on the fact that Tandon would NEVER
put another pin in that socket.
I think that's a rather strange conclusion to some to.
I'd think of it more like this ;
Some 8" drives need the +12V supply, and when it's needed it's on pin 4
of the connecotr. So Tandy wired the harness to allow for such drives.
This particular Tandon drive doesn't need 12V, so pin 4 is missing (or a
no-connect).
How can _adding_ a wire to a harness be a shortcut?
-tony
I'm glad your not working on projects for me then. Having potentially
damaging voltage on a connector that is not needed doesn't sound like good practices
to me.
I have the service manual here for this drive. No where does it say that pin 4 is not
connected to anything. Nor do the schematics I have show that this drive's 7812 (which
is how it is referenced in the print) is optional. The only source for +12 on this
schematic is the 7812, derrived from the +24v line on Pin 1.
Tandy also uses the same connector on the same power supply wiring harness, but with a
completely different pinout (and using the same color scheme in some instances) to provide
power to the card cage riser IN THE SAME MACHINE. If you use this connector on the drive
instead of the riser, bad things happen. If you use the drive power connector on the
riser, bad things happen. The only way to tell them apart reliably is that the drive power
cable has two connectors (to power 2 drives) and the riser power connector has only one
AMP connector.
By the way, if anyone needs these connectors, they are stocked by Mouser and are about
$3.50 each. Search for AMP 1-480270-0. I'm reworking a (different) power supply so I
can put several TM848-2e drives in an enclosure for imaging disks from a PC. I also found
18ga hookup wire in 100' spools for less than $10 per spool at Jameco.
It may save some wiring, but I still think it is a poor practice.
