[sebhc] Diskette termination

Lee Hart leeahart at earthlink.net
Tue May 22 10:49:51 CDT 2007

Carroll Waddell wrote:
> I have the drive manuals for the Siemens FD100 diskette drive. It (along 
> with the schematic) shows the termination resistor pack with 330 ohms 
> going to +5 and 220 going to ground. However the termination resistor 
> packs that were in the drives when I bought them on ebay are 150ohms to 
> both +5 and ground.
> I haven't been able to find any 330/220 resistor packs in any catalog I 
> have. Does anyone know which is correct?

Either the 220/330 or 150 ohm terminator will work. The 220/330 version 
is a bit more "elegant" because it draws much less supply current.

If you use a 150 ohm pack, it almost certainly has just a 150 ohm 
resistor from +5v to each pin. If you plug one of these into an FDD-100 
drive, the pin diagonally opposite the +5v pin is ground, so it puts one 
150 ohm resistor straight to ground -- useless, but harmless.

Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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