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| SCSI HD only works with external terminator attached |
Posted by: robin-fo on 2022-01-16 01:36:07
Hello everyone
I have this 1050MB IBM 50 pin SCSI drive which came out of a Powermac 7500 and worked somewhat reliable on its internal SCSI bus. However, when I use the drive inside a Quadra 700 or Performa 475, it only spins up (!) if an external Terminator or another device with termination is attached.
The jumper for termination is set, so I have no idea where the issue is.
Any thoughts? |
Posted by: ymk on 2022-01-16 01:52:08
It appears to be missing the resistor packs (or equivalent) at U6 and U7.
Only some logic boards provide automatic termination and I don't think the 475 is one of them.
If you don't want an external terminator hanging off the rear of the machine, look for a 50 pin terminator. |
Posted by: robin-fo on 2022-01-16 02:09:15
Ok thanks! So the termination jumper is useless? |
Posted by: ymk on 2022-01-16 02:14:53
It may be useless. I could see Apple shaving off some pennies by ordering a large run of drives like this. |
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