Realities Of Terminator Installation - Yamaha MOTIF6 Owner's Manual

4
Attach the terminator to the SCSI connector (whichever one of the two is not connected) of the last
device in the daisy-chain. Alternatively, turn on the terminator switch of that device.
5
Make sure that the terminator switch is turned OFF for all other devices in the daisy-chain (i.e., all
devices other than the last device).
6
Turn on the power of the external SCSI device(s), and after waiting several seconds, turn on the
power of the MOTIF.
NOTE
Many articles and books concerning SCSI are available. However most of them discuss only the concepts or the
specification, and do not tell you what to do if the system does not work when connected as described. The following
paragraphs will provide more information about SCSI that will help you correct problems which may occur when
SCSI devices are connected. Please read this material if you experience problems. Please be aware that when
connecting SCSI devices, problems with termination and cabling can cause valuable data to be damaged. We regret
that Yamaha can take no responsibility regarding any data which is lost.

■ Realities of terminator installation

Although we have said that a terminator is required at the beginning and end of the SCSI bus, this is a general
principle and not a requirement. For example if the bus is extremely short (45 cm or less), there are cases in which it
is best for there to be a terminator only on one or the other end. However if other drives are connected in addition to
these drives, the situation will again be different.
Also, if the SCSI devices are separated by more than 3 meters, it is said that using a terminator at the 3 meter point is
preferable. In this case, three or more terminators will exist within the SCSI bus.
In this way, the theory and practice of SCSI connections can differ widely. Simply changing a drive in a system that
had been working correctly can cause operation to become unreliable, or adding a drive to an unreliable system can
cause it to start working correctly. In practice, a certain amount of trial and error is necessary.
■ Reasons for SCSI errors
A SCSI bus operates stably only if all the connected SCSI devices are operating correctly. If any of the devices are
producing noise, the other devices will also produce errors, and in the worst case, the boot block of a drive can be
destroyed. (All data in that drive will be lost.)
Also, there are cases in which a system on which data appears to have saved may not have actually saved the data,
resulting in data loss.
The following paragraphs will discuss the reasons for such errors, and will provide a sequence for your
troubleshooting.
• Check the SCSI ID
Make sure that there is no conflict between the SCSI ID of each SCSI device including the MOTIF. When shipped from the factory,
the MOTIF's SCSI ID is set to 6. Be sure to turn off the power before changing the SCSI ID setting.
• Check the terminator
As discussed above, check the location where the terminator is attached.
• Check the SCSI cables
Low-quality SCSI cables will almost always create problems. Always use double-shielded cables. It is also important that the shield
be grounded inside the connector. Long SCSI cables frequently cause problems, so use as short a SCSI cable as possible. Bending or
twisting a SCSI cable in a confined space can cause conductors to break or pins to be broken, so be careful to avoid this.
Yamaha cannot guarantee operation if the SCSI connector of the MOTIF is connected via a converter to any external device other
than a 50-pin SCSI device, such as a Wide SCSI, ATA (IDE), USB, or IEEE 1394 device.
Connecting external SCSI devices
291
MOTIF Appendix