Re: How to build a db25 terminator

Bostjan Lemut (Bostjan.Lemut@klub-kas.si)
Sun, 06 Sep 1998 11:15:48 +0200

Rogier Wolff wrote:

> Bostjan Lemut wrote:
> [Charset iso-8859-2 unsupported, filtering to ASCII...]
> > Hi!
> >
> > I've bought a second-hand UMAX Astra 600S scanner, but it came without
> > terminator (the scanner won't work without it). Since I can't buy it in
> > any computer shop in our country (it's very small one), I decided to
> > make one by myself. The problem is, i can't find a scheme on the WEB.
> >
> > I would be very greatful if anyone send me the scheme how to build the
> > damn terminator.
>
> +5V
> |
> |
> |-|
> | | 220 Ohm
> |_|
> |
> Signal ---------+
> |
> |-|
> | | 330 Ohm.
> |_|
> |
> |
> GND
>
> I don't know what the signal lines are on a DB25 SCSI connector.
>
> Roger.

Hmmmm, I've done some measurment on centronix to db25 adapter and I came out with
a strange results:
according to connections, the signals DB0,1 joins to one pin on db25, also
signals 2,3,4 and 5,6,7 to the third pin
also some control signals join on the gnd.

I also borrowed a terminator and I measured resistance between some pins. As
expected, between pins wich carry db signals, and +5 (assuming) i get 136 ohms,
but on other (i/o) and similar pins I got some weird resistance.
So, could you explain what is ment with "signal" in the resistance scheme. Is it
a DB signal or any signal.

Any other suggestions?

Thanks,

Bostjan

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