[sebhc] Siemens Drive Terminator

Dave Dunfield dave04a at dunfield.com
Fri Jan 6 10:00:35 CST 2006


> But what is the configuration .... how many pins, which pin(s) are common
> .... there were different configurations of resistor terminator packs.
> Anyone have a schematic of the drive?  Or want to take an Ohmmeter to a
> pack?  I do know that the terminators were a stock part, and if I have the
> right information, I can buy one (but it might be a 25 cent part with a $25
> minimum order and a $7 minimum shipping cost).

> > I either need a terminator, a source for a terminator, or a terminator
> > description sufficient to allow me to make my own terminator from discreet
> > parts for one of the Wangco / Siemens drives used in the H-17 and the H-89
> > (the earlier, single-sided drives with the "full face" door).

I'm assuming that this must be "odd" ... could it perhaps be the same as the
terminator used on the 8" Siemens drives:

>From the FDD-100-8 manual, the terminator is described as:

"A dual-inline IC package containing a terminating resistor network for all
input interface lines. For each input line there is a 220-Ohm resistor to +5
volts, and a 330-Ohm resistor to ground".

Pulled one of the spare drives, and took a look at the terminator installed
in it - it is labled "16-3-221-331" which would seem to bear this out.

The pack is a 16-pin DIP.

The manual does not give a pinout, however from what I can measure,
it appears that pin 8 is ground, pin 16 is +5, and pins 1-7 and 9-15 are
the input connections. (Resistance from pin 16 to pin 7 is 39 ohms which
is exactly right for 14 550 Ohm sets in parallel - All other pins read about
138 Ohms to pin 14, and about 146 Ohms to pin 8 - I haven't worked out
what it should be for the complete network, but I suspect this is about
right.

So, if either this is the drive, or your drive uses the same termination,
this should be all you need.

Regards,
Dave

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dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
                http://www.parse.com/~ddunfield/museum/index.html

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