Microtek ScanMaker 4 Instruction Manual

SCSI trouble shooting tip and hints
Common SCSI Problems
The host adapter isn’t recognized on system boot-up. Your computer returns the error, Can’t initialize host adapter.
Possible causes:
•Your SCSI card may not be seated correctly.
•Your SCSI card and some other hardware device are using conflicting system resources, (IE interrupt, I/O address, and/or
DMA)
•A device is locking-up due to issues such as parity checking. Parity checking can be adjusted in the BIOS of the SCSI card.
A Single device not found
•Power supply issue with the failing device.
•The SCSI bus isn’t terminated correctly.
•Your cable (SCSI bus) is too long.
•You have a bad cable(s)
•One of your external device was started after the computer booted up.
Device manager finds the card, but not the devices connected to it.
•There is a bad cable connected to the SCSI bus.
•Termination power has failed or is incorrect
•Lose cable or cable is too long. A loose cable connection can cause intermittent problems.
SCSI system works but shows intermittent lockups.
•Cables are too long
•Incorrect, Low or noisy termination
•Bad cables
•Internal SCSI cables are folded creating a resister-capacitor.
Helpful Hints
1.The only way to properly troubleshoot a situation is to change one thing at a time to see if that cures the problem.
2.If it does not cure the problem you should reverse the change before make another change.
3.Document each step you take in troubleshooting a SCSI problem.
4. There are many cheap SCSI cables on the market that don’t meet SCSI specifications. These can cause all sorts of SCSI
problems.
5.Check to see if each SCSI device has it’s own unique SCSI ID.
6.Make sure you know the SCSI ID of your SCSI host adapter. Most SCSI host adapters are factory default at SCSI ID 7.
7. The first and last device on a SCSI chain must be terrninatel.
8. Are you attaching are external Narrow SCSI device to a wide SCSI. If so you need to terminate the unused lines or the
"high nine". To do this you need a special 68 to 50 pin external SCSI cable with termination built-in for the unused lines. Or
you can use a 68 to 50 pin adapter with termination built-in for the unused lines and use a standard 50 to 50 pin external
cable.
9.If your external device has a termination switch built into the enclosure you may be double terminating.
10. Are you powering on external SCSI devices prior to booting your system?