barry@primerd.prime.com (03/13/90)
There have been a few queries lately about removing internal termination
from a SCSI device. The reason one would want to do this is that the
first and last device in SCSI chain must be terminated. An internally
terminated device _must_ be at the end of the chain, which limits where
it can be used in a chain of more than one device. Switching to the use
of an external terminator adds configuration flexibility at the cost of
the external terminator (about $30).
Generic instructions:
An internal terminator is a set of three resistors that should be near
the internal 50-pin SCSI connector on the device. This is not to be
confused with the 50-pin connector on the outside of the case containing
the device. The internal connector on the device will have flat 50-pin
cable connecting it to the back of the external connector on the case.
Some devices have a jumper that controls whether or not the terminator
is power - you can remove termination on these devices by removing the
jumper ... if you have a manual that identifies the jumpers. You can
_always_ remove the internal termination by removing the three resistors
- these are likely to be a BLUE ceramic package with 8 pins. You have
to remove all three of the resistors (with the device unplugged, of
course).
When in doubt, leave it alone and seek an expert.
Hope this helps,
Barry
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Barry Wolman | barry@s66.prime.com
Principal Technical Consultant | 500 Old Connecticut Path
Prime Computer | Framingham, MA 01701
| 508/879-2960, ext. 4187
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