I noticed on the FDC on the mainboard, there's
maybe 2 or 3 pins that are
noticably absent from the normal connector. Perhaps they absconded with the
signals. I know absolutely nothing about the floppy drive interface & cable
On a normal flopy conenctor the pins are numbered like this
1 2
3 4
5 6
...
31 32
33 34
Pin one is normally marked, it's near the coloured edge of the cable.
Now, on PC floppy drives, all the odd numbered pins -- the entire column
-- are grounds. All the signals are on even numbered pins
[I specified PC drives here, becuase in a few systemsm, there are drives
with 34 pin connecotrs that don't have a speparate power conenctor.
Instead some of the odd numbered pins are +5V, some are +12V, and the
rest are grounds. Also, I have pet drives where there's an active signal
on pin 1, but not in PCs]
Ok after that aside... 17 grounds is enoguh for anyone, and it wasn't
uncommon for one of those pins to be missing on some machines, and the
corrisopondign hole on the socket (on the cable) to be blocked up. That
way, the cable would only fit the floppy drive conenctor (other 34 pin
conenctors i nthe machine had different pins missing), and only the right
way round. Made it easier for field servoids...
If your floppy connector is misisng a couple of odd-numbered gound pins,
then nothing to worry about. But if it is missing some signal pins, it's
quite posible (likely?) that what's misisng are the drive sleect and
motor on signals for the second drive. Using the pin numbering I've
shown, what pin numbwes are not rhere. IIRC it's 10,12,14,16 that carry
the drive sleect and motor on lines on a PC.
-tony