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Punkyclown's picture
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Joined: 2017 Nov 9
Mac SE internal SCSI drive failed arbitration

Hi All,  I replaced my SCSI hard drive in my Mac SE and now when I tried to set it up it tells me "Arbitration failure Check all Termination setups".
The drive has an 8 pin jumper on it, I guess that is not the issue but do not know. Where would I set termination on an internal drive?
Appreciate any help I can get, thank you,
Brad Hansen

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sfp1954's picture
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Joined: 2013 Dec 29

If you search the internet with the make and model # you should be able to find the jumper settings for the drive. The 8 pins are probably for setting the SCSI address (0-7).
Many older SCSI drives had three sets of 8 pin terminator resistors on the bottom near the SCSI jack. If they have been removed they will need to be replaced for proper termination.
Or there may be a cluster of 4 or 6 pins on the bottom which can be jumpered to turn on SCSI termination.

24bit's picture
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Joined: 2010 Nov 19

Termination was the most common issue with SCSI daisy chains.
The more recent SCSI devices had some way to set termination on/off by jumper or else.
The very old stuff had groups of termination resistors mounted on the hard drive´s PCB - or not.
Some resistors packs are still kicking around here, I would gladly donate them for your SE:

P1010092

Another way (not so much recommended) is terminating the bus after the internal HDD by a small piggy tail on the 50pin ribbon cable. An empty connector after your HDD is needed obviously and 50pin termination resistor packs may be really hard to find these days.
Edit:
Not that hard to find actually: https://www.amazon.com/Active-Internal-50-Pin-Terminator-Ribbon/dp/B016S...

The SCSI ID setting should not matter much, if your HDD is the only device except the HBA.
The HBA gets ID = 7 by default. A HDD with no ID jumper set will have ID = 0.

Let me know if I should send the little yellow combs by snail mail if your HDD has the spots to plug them in.

adespoton's picture
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Joined: 2015 Feb 15

I always used a clip-on terminator at the end of the SCSI chain and never had issues....

24bit's picture
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Joined: 2010 Nov 19

Sure, never had issues myself either. All external SCSI encasements for SyQuest drives or similar were terminated that way.
Still a faint memory tells me that the SCSI-1 "rules" asked for avoiding pig tails for termination.

Troyd's picture
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Joined: 2014 Nov 14

I had the same recently with a couple of my SEs. The simplest method is, as suggested, to use a termination dongle on the SCSI cable. Even after correctly setting termination and IDs, I found that some hard drives just did not want to cooperate with the SE, particularly those where you had to use an adapter to convert from 80 or 68 pin to 50 pin. I had the best results with WD drives and the most frustration (arbitration errors galore) with Compaq drives, even with active termination dongles.

If your replacement drive is not Apple branded, you will need to use a 3rd party utility to initialise and partition it. I found that Lido worked best out of all the options. If your drive is more than 2GB in size, you can partition it into several volumes and all will mount but only the first volume will be bootable.

Punkyclown's picture
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Joined: 2017 Nov 9

Wow!, Thanks for all the terrific advise, I will work through these suggestions and see what happens.
Brad Hansen

sstaylor's picture
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Joined: 2016 Aug 26

If the "8-pin jumper" is 4 pairs, it is likely that 3 of the pairs are for SCSI ID, with one pair for termination on/off. As stated above, do a search for the drive and you should be able to find the pinout. Or it may even be silkscreened on the PCB near the jumpers.