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SCSI ID Selector Switch on back of Hard Disk SC

Posted by: JDW on 2020-07-16 11:26:46 I have a Hard Disk 20SC external SCSI drive enclosure that has a SCSI ID selector switch on back.  Because I am using a non-stock IBM DGHS 4.5GB drive inside, I've left the SCSI ID select switch cable disconnected.  But I am eager to change the SCSI ID on the fly.   Here's a photo of the drive label, showing the SCSI ID jumper settings: I believe the precise jumper settings follow what is shown on page 17 of this PDF. And here's a photo of the inside of my HD20SC (a still image from my PSU recapping video): It seems that an ST-225N was the stock drive and its SCSI ID jumpers seem to correspond to that blue connector in my above photo: What I am curious about is how the HD20SC's SCSI ID selector cable works.  I haven't yet torn apart my HD20SC to figure it out myself.  I will do that, but I wanted to post here first. The above ST-225N diagram shows 4 pairs of pins that can be shorted to select SCSI ID, but the drive enclosure's blue connector only has a 6-wire cable, meaning it could only control 3 pairs, not 4. Any thoughts?

Posted by: JDW on 2020-07-16 14:35:18 Now that I ponder the DGHS's jumper table a bit further, it seems that only 3 pairs of pins are jumpered in order to select SCSI ID's 1 to 7.  So it should be a simply matter of extending the wires of that Blue connector so it reaches the front of the drive.

Posted by: superjer2000 on 2020-07-16 14:38:27 Yes. It's generally only ever three jumpers, one for each bit of a 3 bit address allowing for 0 to 7.

Posted by: JDW on 2020-07-31 12:12:52 I made a video on the subject here, released today...

Posted by: erichelgeson on 2020-08-05 00:56:35 Great video, I'm going to see if I can follow the same procedure for the SCSI selector on my external CD ROM drive - put a 300i in a Panasonic SCSI enclosure (Panasonic drive was dead) - would be nice to be able to select the ID's.

Posted by: JDW on 2020-08-05 09:05:28 Thank you for the kind words, Eric.  Getting the SCSI ID selector to work on my HD20SC has been very useful, so I know you will benefit from the effort required to make it happen on your CD drive.

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