[sdiy] Ensoniq ASR-X weirdness

[rsdio at audiobanshee.com]

As a general rule, every SCSI chain must be terminated twice - once at each end. Very few devices force termination, because that would mean they could only be used at the end of the chain. So, the user is expected to manually put termination at each end of the chain. If your SCSI devices have two connectors, you can just plug a SCSI terminator into the empty connector on the device at the end of the chain. A few devices - like computers - would have built-in termination that could not be defeated or removed, with the assumption that they'd always be at the end of a chain and not in the middle.

My SCSI bin has a handful of SCSI terminators in the pile along with all the various cables. It was just a fact of life in those days. Eventually, thinking about things like termination became a thing of the past. But you have to learn this stuff if you're using old gear from those decades.

I do not know whether the ASR-X has built-in termination, but the Zip drive will need it. Some drives have internal jumpers allowing you to turn on termination without needing an external terminator. Then you have to keep track of which devices are internally terminated and make sure they're at the end of the chain.

Of course, if you only have two devices then none are in the middle. Technically, this means that both will need termination. If you don't have termination on your Zip drive then the whole SCSI system won't work reliably.

Brian Willoughby


On Dec 1, 2015, at 5:58 PM, Travis Thatcher <recompas at gmail.com> wrote:
> I've got a terminator and a scsi cd drive I can try on the end of the
> chain tomorrow. I think it is weird that even if I insert a brand new
> pc formatted zip disk the status still says 'Unreadable'. I thought
> the ASR-X used DOS formatting... I may just give up in the end and get
> an sd floppy emulator. I don't plan on putting huge samples on this
> thing but it'd be nice to have the larger storage option.
> 
> On Tue, Dec 1, 2015 at 4:35 PM, BrightBoy <jdec at mindspring.com> wrote:
>> See if you can track down an APS Sentry II SCSI terminator
>> (or an APS SCSI enclosure that also has the same built-in/selectable
>> termination)
>> 
>> I also ran across this which might provide some clues:
>> 
>> http://www.chickensys.com/kb/eps-asr/004.html
>> 
>> Jeff
>> 
>> -----Original Message-----
>>> From: Dan Snazelle <subjectivity at hotmail.com>
>>> 
>>> When I had an eps16+ I had to buy an old external scsci drive to put in the chain after the Iomega Zip drive
>>> This was purely to terminate the scsci as the hard-drive didn't even have much storage
>>> 
>>> On Dec 1, 2015, at 12:54 PM, Sarah Thompson <plodger at gmail.com> wrote:
>>>> You could ring out the lines and look for the resistance to ground. If termination is on, it should be relatively low. If it's off, then it would be a few k ohms. Some kinds of active termination may fake out your meter, however.
>>>> 
>>>> Another option would be to hook everything up as normal and fire it up and look at the signal with a good low capacitance scope probe, active preferably, and see whether the edges are nice and square or whether they are ringing. Ideally you'd want to use a fairly fast scope, but SCSI is fairly slow by modern standards.
>>>> 
>>>> Sarah
>>>> 
>>>> On Dec 1, 2015, at 8:36 AM, Travis Thatcher <recompas at gmail.com> wrote:
>>>>> Thanks Dave,
>>>>> 
>>>>> I wonder if there's an issue with the termination...I think Iomega Zip
>>>>> drives are meant to work without mods with the ASR X however I'm
>>>>> curious if the internal termination of the ASR is malfunctioning. It
>>>>> is set to 'on' in the settings. Does anyone know how to actually
>>>>> electrically test termination on a scsi chain?
>>>>> 
>>>>> On Mon, Nov 30, 2015 at 8:25 PM, Dave Brown <davebr at earthlink.net> wrote:
>>>>>> I don't know anything about ASR-X.  I have the EPS 16+.  What I do know on
>>>>>> this version the SCSI bus attenuation power has to come from the drive which
>>>>>> is very non-standard (in my experience).  I've yet to see a drive that
>>>>>> enables this easily so on my drives I have to modify them to provide it (the
>>>>>> drive provides the power to the EPS 16+ for termination in the synth).  I
>>>>>> don't know if the ASR-X does this or not but it might be worth checking on
>>>>>> the SCSI instructions.  Just a wild guess.
>>>>>> 
>>>>>> Dave
>>>>>> 
>>>>>>> -----Original Message-----
>>>>>>> Sent: Monday, November 30, 2015 3:06 PM
>>>>>>> 
>>>>>>> Not necessarily synth DIY so apologies but I'm stumped on this one. I have an
>>>>>>> ASR-X (the black one) that won't format Zip disks. It starts to format and then
>>>>>>> stops at 1.1% every time. I've tried 2 different zip drives and many different
>>>>>>> brand new discs with the same results every time. Tried at least 2 different
>>>>>>> scsi cables as well. Has anyone else experienced this? I unfortunately don't
>>>>>>> have access to a scsi hard drive or another device to test stuff with. Any
>>>>>>> suggestions would be greatly appreciated.
>