Ensoniq EPS-16+ SCSI issue

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belzrebuth
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Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Tue Mar 10, 2020 2:34 pm

I did the scsi mod (5v on the pin 25 for termination power) as described here :
http://zine.r-massive.com/esp16-rack-mod/
I then tried to attach an iomega zip 100 drive to the sampler but no matter what I do all I get on the screen when trying to format it is "unconnected scsi dev".
I know the drive is good because I've been using it with other samplers.
I'm not sure about the 25pin to 25pin cable to be honest but I checked it with a multimeter and I think it's probably the scsi board itself.
I've tried all the zip drive settings (scsi id 5/6 termination on/off) to no avail.
When the sampler boots up I get "searching scsi device" which means that the scsi board must be operating to a certain point.
I also can't access the zip disk when trying to switch my save disk option (floppy or scsi).
I've also tried the mod with only a wire in case the voltage wasn't enough.

I don't know what's going on, since all I read online is that it should work without issues considering the mod has been applied.
Btw are the schematics for the scsi option avalaible anywhere?

Rasputin
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Re: Ensoniq EPS-16+ SCSI issue

Post by Rasputin » Wed Mar 11, 2020 5:32 pm

belzrebuth wrote:
Tue Mar 10, 2020 2:34 pm
Btw are the schematics for the scsi option avalaible anywhere?
You were already so close to the schematics.

http://zine.r-massive.com/ensoniq-techn ... chematics/

blueknob
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Re: Ensoniq EPS-16+ SCSI issue

Post by blueknob » Wed Mar 11, 2020 7:42 pm

I have an EPS16+ rack that came with a ZIP100+ and I'm sure it worked without any mods. Then Pluto was declared not to be a gas cloud after all and then ZIP100 no longer seemed to work. I added the diode to the 5V pin 25 and it all seemed to work again!? Just a few pointers, do measure the voltage on pin 25, I think it sits about 4.3V I recall mine didn't work due to a tant cap fault on the scsi board. Anyway an easy fix, I also put the scsi power on a switch as I found having term power on and no scsi device attached, on boot up the EPS16+ gets confused and throws a wobbley. I think it hangs, locks up.

You'll notice the EPS16+ scsi board has termination resistor packs installed, usually in SIL sockets. Also there are a few versions of the ZIP100, mine are the + version, that I gather auto detect scsi or printer is attached and does the term thing if required.

I assume you can boot the EPS16+ from floppy, and the problem starts when asking it to "change storage device" hopefully to see something. I think it's open loop, you have to know what scsi address to use. Meaning ZIP on scsi 5, then "change storage device" to 5 and things should work.
From what I've learnt, the scsi chip in the ESP16+ is a tough beast, so I would think it's ok. I tend to use a cdrom drive for testing, for some reason they seem easier to setup. I use the Apple CD200 (or 300) anyway ones I know that work as not all do, there are lists.

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Re: Ensoniq EPS-16+ SCSI issue

Post by Rasputin » Thu Mar 12, 2020 3:14 pm

blueknob wrote:
Wed Mar 11, 2020 7:42 pm
I have an EPS16+ rack that came with a ZIP100+ and I'm sure it worked without any mods.

I also put the scsi power on a switch as I found having term power on and no scsi device attached, on boot up the EPS16+ gets confused and throws a wobbley. I think it hangs, locks up.
Is it possible that you happened to have something else on the SCSI chain with the Zip initially? If you did at first and then later hooked up the Zip solo then that might explain how it worked without a mod and then stopped working until the mod.

The SCSI power switch is an interesting idea, but I think there's something else at play because I have an EPS16 rack with the mod and it boots normally without any SCSI devices. Not saying it doesn't ever happen to certain machines in specific situations, but apparently it depends on some other factor(s).

Could be one of those mysterious "Jupiter is in retrograde" things, I don't know :D

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Re: Ensoniq EPS-16+ SCSI issue

Post by blueknob » Thu Mar 12, 2020 3:59 pm

Yeh it confused me. My ZIP100Plus came with a special iomega Active Sense scsi lead which doesn't allow chain of scsi devices it was just the sampler to ZIP and nothing else. I bought the sampler and ZIP as a pair and I'm sure it worked with no modifcations. The planets moved and suddenly that combo stopped working!? All I can think of is I was experimenting with Mac OS9 and scsi, something went odd one day. I've had a very close look at the EPS16+ scsi card, everything seems ok. But then I connect the same ZIP100+ to my EPS16+ keyboard version (no separate scsi power feed) and it works! Very strange :roll:

If your EPS16 doesn't mind having term power all the time and boots with no scsi device attached I wonder if the design is in that ambiguous state. Works for one person but not the other. I can only think of tolerances, PSU voltage - diode forward drop and the tolerance on the resisitors might just be on the threshold of the scsi chip input thresholds. Maybe I need to wait for a full moon.

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Re: Ensoniq EPS-16+ SCSI issue

Post by Hyde » Fri Mar 13, 2020 8:56 pm

I've modded both my cards with just a wire, no diode(EPS16 & EPS6 rack). Both work fine with the original Zip Drive. The updated drives may not work, from what I remember. There are some aftermarket SCSI cards out there with the upgrade. The ZipDrive came out about the same time as the ASR10. The ASR10 card ran the ZipDrive just fine.

Make sure you have the first series of Zip Drive. Make sure you are powering up in correct order. Make sure you are using a "SCSI cable". Make sure you have termination on the drive set to on, & make sure your drive ID matches the machine. It would be pretty uncommon for the SCSI card to be bad. Re-check your soldering work.
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belzrebuth
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Re: Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Mon Mar 16, 2020 7:13 pm

Okay,
As I now have two units I can see some differences when swapping the scsi card between them.

The iomega drive does not work on either.
On the first sampler all I get is the "unconnected scsi dec" while trying to format whereas the second sampler can probably detect the device because the "formatting" message lasts a little bit longer than on the first one and comes with an error. (file operation error)
Also on the "change storage device" option the first sampler responds "invalid scsi device" while the second reports that this is not an eps partition or something along those lines.

On the first sampler both chips near the floppy and scsi ribbons have been replaced for some reason.
The soldering is not top notch so whoever did this might have damaged the traces or the vias if he/her was not having the right tools to properly desolder the chips.

I will buzz the traces of the 7406 and 7407 chips near the area and check for any abnormalities.

On the second sampler the SCSI should be working though, and it is not.
I will try a sealed zip disk and see if that's the problem.
The zip drive works with my akai s1100 so I know it works okay.

The only thing I haven't checked so far (hardware wise) is the actual 25pin cable but I think it's okay since I've probably never used it and I think I've bought it new.

I can test with another cable later if I manage to find one on my storage.

The other thing I could try is to format the zip disk on a Windows XP computer with the Ensoniq option (I think there's an extension for the Total Commander program) and see.

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Re: Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Tue Mar 17, 2020 12:05 am

U17 and U16 are unrelated to SCSI so I left them alone.
What I did is dug out an old Windows XP PC and formatted a zip disk with the Ensoniq FS Total Commander plugin.
With the ensoniq formatted zip disk I still get the same behavior.
I get the feeling that the "second" sample is good with the scsi board it's seems to be responding kind of normal..
I also get an orange access light on the iomega zip when I try to format it.
So maybe it does not "like" this particular drive/setup or whatever.

But the "first" sampler definitely has a different behavior.
It's like the scsi board is not working 100% on that unit.
Another difference I've noticed is than on initial boot on the "first" sampler I get "scsi installed" message and then "searching scsi dev".
On the "second" sampler I don't get the "scsi installed" message only "searching scsi dev".
Where should I look next?
I'm kind of stuck for ideas..
It seems that the SCSI (AUX 3) header goes straight to customs ICs and the CPU.

I could replace the CPU since they're very easy to source but I believe I have to ensure that I have one 100% working SCSI setup in order to properly compare the two units.
I can also borrow another iomega drive and check if the actual drive has any issues..Or the cable..I don't know..
I'll try to find another 34pin ribbon as well..
Maybe it's trivial, the 25pin cable or the ribbon..
I'm open to any suggestions though.!

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Hyde
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Re: Ensoniq EPS-16+ SCSI issue

Post by Hyde » Fri Mar 20, 2020 4:47 am

Sorry to ask the dumb question but, are there 2 switches on the back of the zip drive? one for scsi ID & the other for termination?
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belzrebuth
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Re: Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Fri Mar 20, 2020 4:34 pm

Yes, the Iomega SCSI drives can be id 5 or 6 and terminated or not.
There are two switches on the back to set scsi id and termination on/off.

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Hyde
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Re: Ensoniq EPS-16+ SCSI issue

Post by Hyde » Sat Mar 21, 2020 4:29 pm

& you have formatted the disk? or is that where you are having issues? After the mod on my EPS16 scsi cards, I've had zero issues. The startup sequence is always important. The problem I've had is a bad drive I purchased, ruined a coupe disks. It would start up normally, I could load something. as soon as it tried to access the OS "click".
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Re: Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Sat Mar 21, 2020 7:28 pm

I don't know got a little fed up with it so I sold the sampler with the scsi board :mrgreen:
I kept the other without the scsi..
Have a broken Casio FZ-20M which concerns me more than having SCSI on a 2MB machine (I'll probably start a thread about that Casio as well when I get around fixing it).
I get by with a HxC flashed gotek just fine on the EPS 16+ so having a SCSI board is not that important since there's not much onboard ram anyways.
I know I should've investigated further but the new owner has a couple of SCSI drives he could try so when I learn something new I'll let you all know.

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Hyde
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Re: Ensoniq EPS-16+ SCSI issue

Post by Hyde » Mon Mar 23, 2020 5:18 am

I understand. Electronics can be daunting. I take on fix it projects , every once in a while. Sometimes I can figure it out. I wish I could find an internship to learn more. Online advise is great, but usually way over my head. Would be great to have someone to point & explain.
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Re: Ensoniq EPS-16+ SCSI issue

Post by belzrebuth » Mon Mar 23, 2020 10:48 am

I'm an undergraduate electrical engineer (transitioning from another field I've spent a few years working) so it's more than a hobby for me now to be honest but repairing one of my two EPS 16+ units was enough to make me want to move on.
SCSI (on the unit that I've sold) is probably working.
Can't really think of a reason it's not; maybe it was my iomega drive or even the 25pin cable since the drive is working with another cable with my S1100.
Ensoniqs are a bit fussy with their SCSI; or so I read on the internet; I can't be sure.
I'd love the buyer to call me and tell me that it's working though, it'd be nice end to my EPS story.

Can't wait to get the broken FZ-20 on the bench.. :D

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