ENSONIQ ASR-10 Wartungshandbuch PDF herunterladen (Seite 78)

SCSI

Infomtion

SCSI Information

SCSI Cables

SCSI cables are available from computer stores in a price range from about $12 to $50.

Usually the less expensive cables cut comers on materials and they may become unreliable. It is worth

the extra money to purchase a good SCSI cable. Most SCSI drives come with a 25-pin to 50-pin cable.

Cramolin

We recommend using Cramolin Red on SCSI cable connections. It is a continuity enhancer

that makes connections more reliable. It costs about $20 for a 2 oz. bottle, but it’s worth it!

Termination

SCSI drive must supply its own termination power.

Termination is a very important factor especially when you consider all the different units in your SCSI

setup with different power supply sources. The Macintosh computers that don’t have hard drives also

don’t have termination. Hard drive and computer power supplies introduce noise into a system and this

noise confuses the SCSI software. The SCSI software gets confused because it can’t tell what’s noise,

what is a

”

1”

or what is a “0”. Termination filters out this noise so the software can do its job.

SCSI Terminators

The SCSI terminator is simply a resistor network on each SCSI signal on the

SCSI bus. The terminator prevents reflection or ringing on the signal lines, allowing reliable high speed

data transfers.

Warning! A system configuration (two or more SCSI storage devices) must have two terminators.

Damage can result if more than two terminators are present.

The terminator is either external or internal. The external terminator resembles two 50-pin SCSI

connectors mounted back to back and encased in plastic. It is plugged into the SCSI connector of the

device and then the‘ SCSI cable is plugged into the terminator. The internal terminator is simply the

resistor network, typically as resistor packs on the SCSI device controller circuit board. The

documentation that accompanies the SCSI device usually describes the procedures required for

installation and removal of terminators. The SCSI installed in the ASR-10 Rack (or the SP-3 SCSI Kit

for the ASR-10 keyboard unit) contains internal termination via removable resistor packs (do not remove

the resistor packs unless directed by the ENSONIQ Customer Service). Note that the ASR-10 supplies

power to its own terminator only. Therefore, any SCSI storage devices used with the ASR-10 must

supply power to the SCSI bus.

Error Messages that may appear while you are using the ASR-10 with SCSI

UNCONNECTED SCSI DEV A SCSI device that was detected by the ASR-10 at bootup is no longer

connected or turned on.

l What to do:

Check your SCSI connections. If your SCSI drive has a changeable

ID number, make sure it matches the SCSI device number you have

chosen in the CHANGE STORAGE DEVICE command.

INVALID LOAD DEVICE No SCSI device with this ID was connected to the network when the

ASR- 10 booted up.

l What to do:

Use the CHANGE STORAGE DEVICE Command to verify that you

are using the correct SCSI device number.

ASR

Service Manual

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