Quantum Q250 User Manual

2.2.4 SCSI Bus Signal Descriptions
All signals are true low and use open collector drivers (see Figure
2-6 for a typical circuit). A termination is required at each
physical end of the bus. Three resistor networks in sockets are
provided as terminators. Drives are shipped from the factory with
the terminators plugged in. See Figure 2-9 for locations on the PCB.
5'1
CAUTION
Only the two devices at the physical ends of the SCSI bus
are allowed to have terminators: remove terminators from
all other devices on the bus (unplug all three terminator
packages). If the additional terminators are not removed,
the bus drivers may be damaged because they will sink more
current from the +5 V supply than the 48 rnA they are rated
to carry.
CAUTION
Plug-in terminator packages are polarized, and must be
plugged in correctly. On each package, pin 1 is marked
with a dark band, and must face the "1" that is screened on
the PCB. All terminators face the same way. If in doubt
about the correct orientation, consult Figure 2-9.
TERMPWR (PIN26)
r--------- __ ~~---- __ ~--------------~--~------~--------~
5V
-SIGNAL
~----~----~--------~---------------+--~------4---~------1
GROUND
~----~----~--~----~---------------r----------T---~----~
DEVICE
WITH
TERMINATOR
"----------.. -------)
V
DEVICES WITHOUT TERMINATORS
DEVICE
WITH
TERMINATOR
Figure 2-6: SCSI Bus. Typical Circuit of a Signal Line
2-10
5V

Quantum Q250 Specifications

General

Brand	Quantum
Model	Q250
Category	Storage
Language	English